CARDIOVASCULAR SYSTEM AND BLOOD • • • • • The heart is the muscular organ that is essential for life because it pumps blood throughout the body The heart is a member organ of the cardiovascular system Cardiovascular System consists of the heart, the blood vessels, and the blood The heart of a healthy adult, at rest, pumps approximately 5 liters (L) of blood per minute. For most people, the heart continues to pump at approximately that rate for more than 75 years. TWO TYPES OF CIRCULATION PULMONARY CIRCULATION • To lungs • The heart is actually two pumps in one • The right side of the heart pumps blood to the lungs and back to the left side of the heart through vessels of the pulmonary circulation SYSTEMIC CIRCULATION • The left side of the heart pumps blood to all other tissues of the body and back to the right side of the heart through vessels of the systemic circulation • • • • FUNCTIONS OF THE HEART 1. Generates blood pressure → Contractions of the heart generate blood pressure, which forces blood through the blood vessels 2. Routes Blood → The heart separates the pulmonary and systemic circulations, which ensures the flow of oxygen-rich blood to tissues. 3. Ensures one-way blood flow → The valves of the heart ensure a oneway flow of blood through the heart and blood vessels 4. Regulates blood supply → Changes in the rate and force of heart contraction match blood flow to the changing metabolic needs of the tissues during rest, exercise, and changes in body position • HEART CHARACTERISTICS The size of the heart is a size of a fist Weighs less than 1 pound It is located between the lungs and thoracic cavity Its orientation especially the apex or the bottom of the heart is directed towards the left side PERICARDIA The heart lies in the pericardial cavity which is formed by a pericardium or a pericardial sac PERICARDIUM OR PERICARDIAL SAC • Which surrounds the heart and anchors it within the mediastinum 1 • It is a double layered sac that anchors and protect the heart • Consists of two layers: 1. Fibrous pericardium → Outer; tough fibrous connective tissue 2. Serous pericardium → Inner; made of connective tissue → Composed of two parts – parietal Pericardium and Visceral Pericardium → Parietal Pericardium – membrane around the heart’s cavity → Visceral Pericardium or Epicardium – membrane in the heart’s surface ο The parietal and visceral pericardia are continuous with each other where the great vessels enter or leave the heart • The pericardial cavity’s space around the heart is filled with pericardial fluid produced by a serous pericardium that helps reduce friction as the heart moves towards the pericardium HEART EXTERNAL ANATOMY CORONARY SULCUS • Extends around the heart, separating the atria from the ventricles. • Two grooves, or sulci, which indicate the division between the right and left ventricles, extend inferiorly from the coronary sulcus ANTERIOR INTERVENTRICULAR SULCUS • Extends inferiorly from the coronary sulcus on the anterior surface of the heart POSTERIOR INTERVENTRICULAR SULCUS • Extends inferiorly from the coronary sulcus on the posterior surface of the heart • SIX LARGE VEINS That carry blood to the atria of the heart SUPERIOR VENA CAVA & INFERIOR VENA CAVA • Carry blood from the body to the right atrium FOUR PULMONARY VEINS • Carry blood from the lungs to the left atrium GREAT VESSELS OR GREAT ARTERIES • Two arteries, carry blood away from the ventricles of the heart PULMONARY TRUNK • Arising from the right ventricle • Splits into the right and left pulmonary arteries RIGHT AND LEFT PULMONARY ARTERIES • Which carry blood to the lungs AORTA • Arising from the left ventricle, carries blood to the rest of the body INTERNAL ANATOMY OF THE HEART The heart is a muscular pump consisting of four chambers: the right and left atria and the right and left ventricles LEFT & RIGHT ATRIA or ATRIUM • Superior chambers or a holding chamber • Small thin-walled, contract minimally to push blood into the ventricles • It is separated by the interatrial septum • LEFT & RIGHT VENTRICLES • Inferior chambers or a pumping chamber • Contracts forcefully to propel blood out of the heart • The right ventricle pumps blood into the pulmonary trunk 2 • • • The left ventricle pumps blood into the aorta The left and right ventricles are separated by the muscular interventricular septum HEART VALVES one-way flow of blood ATRIOVENTRICULAR (AV) VALVE • is located between each atrium and ventricle • Two AV Valve TRICUSPID VALVE → between the right atrium and the right ventricle has three cusps BICUSPID VALVE OR MITRAL → between the left atrium and the left ventricle has two cusps • Each ventricle contains cone-shaped, muscular pillars called Papillary muscles. • These muscles are attached by thin, strong, connective tissue strings called chordae tendineae to the free margins of the cusps of the atrioventricular valves. • When the ventricles contract, the papillary muscles contract and prevent the valves from opening into the atria by pulling on the chordae tendineae attached to the valve cusps, this will prevent backflow SEMILUNAR VALVE • Have three half moon shaped cusps • Located between each ventricle and its associated great artery • Prevents backflow PULMONARY SEMILUNAR VALVE • Located between the right ventricle and the pulmonary trunk AORTIC SEMILUNAR VALVE • Located between the left ventricle and aorta the ventricles and provides a rigid attachment site for cardiac muscle. 1. 2. 3. 4. 5. 6. 7. BLOOD FLOW THROUGH HEART Right Atrium 8. Pulmonary Veins Tricuspid Valve 9. Left Atrium Right Ventricle 10. Bicuspid Valve Pulmonary 11. Left Ventricle Semilunar Valve 12. Aortic Semilunar Pulmonary Trunk Valve Pulmonary 13. Aorta Arteries 14. Body Lungs CARDIAC SKELETON or FIBROUS SKELETON • A plate of connective tissue • Consists mainly of fibrous rings that surround the atrioventricular and semilunar valves and give them solid support • This connective tissue plate also serves as electrical insulation between the atria and 3 CARDIAC CIRCULATION • Blood from superior vena cava and inferior vena cava enters into the right atrium before it enters into the right ventricle it then passes to the tricuspid valve • From the right ventricle it passes through the pulmonary semilunar valve before it reaches the pulmonary trunk • It then goes to the pulmonary artery (the only artery that carries unoxygenated blood) before it reaches the lungs • From the lungs, there is a gas exchange, it then enters to the pulmonary veins (the only vein that carries oxygenated blood), it enters into the left atrium, and it passes to the bicuspid valve or mitral valve towards the left ventricle, from the left ventricle, blood flows towards aortic semilunar valve before it reaches the aorta then going to the system ο From aorta, blood goes to the Coronary arteries, and it enters into the heart tissue through Coronary Circulation, it enters into the Coronary Sinus Cardiac Veins before it returns back to the right atrium BLOOD SUPPLY TO THE HEART CORONARY ARTERY • Supply blood to the heart wall • Originates from the base of aorta, above the aortic semilunar valve LEFT CORONARY ARTERY • Originates on the left side of the aorta • It has three major branches: the anterior interventricular artery, the circumflex artery, and the left marginal artery • Supplies blood to the anterior wall of the heart and left ventricle RIGHT CORONARY ARTERY • Originates on the right side of the aorta • Supply most of the wall of the right ventricle • It extends around the coronary sulcus on the right to the posterior surface of the heart and gives rise to the posterior interventricular artery, which lies in the posterior interventricular sulcus. • The right marginal artery extends inferiorly along the lateral wall of the right ventricle CARDIAC VEINS • Drain blood from the cardiac muscle. • Their pathways are nearly parallel to the coronary arteries, and most of them drain blood into the coronary sinus, a large vein located within the coronary sulcus on the posterior aspect of the heart. Blood flows from the coronary sinus into the right atrium • Some small cardiac veins drain directly into the right atrium. HEART WALL The heart wall is composed of three layers of tissue: the epicardium, the myocardium, and the endocardium EPICARDIUM • Also called the Visceral Pericardium • Outside surface of the heart MYOCARDIUM • The thick, middle layer of the heart, the composed of cardiac muscle cells • Responsible for contraction of the heart chambers. ENDOCARDIUM • The smooth inner surface of the heart chambers • 4 CARDIAC MUSCLE ACTION POTENTIALS → Pacemaker potential – changes in the permeability of the cell membrane that produce action potentials 1. Depolarization Phase • Na+ channels open • Ca2+ channels open • It facilitates the sodium to go inside the cell or sodium influx 2. Plateau Phase • Na+ channels close • Some K+ channels open • Ca2+ channels remain open • The action potentials take a longer period because it keeps the Calcium channels open • In skeletal muscles, action potentials the 2 millisecond • In cardiac muscles, it takes 2-500 millisecond 3. Repolarization Phase • K+ channels are open • Ca2+ channels close • Facilitates the entrance of the Potassium going inside the cell • During repolarization, the sodium channels are exiting and going outside the cell ATRIOVENTRICULAR NODE (AV NODE) • located in the lower portion of the right atrium • The action potentials from SA node are sent to this node and the action potentials spread slowly through it • • • CONDUCTION SYSTEM OF HEART The conduction system of the heart includes the sinoatrial node, atrioventricular node, atrioventricular bundle, right and left bundle branches , and Purkinje fibers Contraction of the atria and ventricles is Coordinated by specialized cardiac muscle cells in the heart wall that form the conduction system of the heart All the cells of the conduction system can produce spontaneous action potentials. SINOATRIAL NODE (SA NODE) • Lower portion in Right Atrium • functions as the heart’s Pacemaker • initiates the contraction of the heart • Action potentials originate in the SA node and spread over the right and left atria, causing them to contract. • Has a larger number of Ca2+ channels ATRIOVENTRICULAR BUNDLE • Action potentials from AV node travel to AV bundle • AV bundle divides into a left and right bundle branches • Slow rate of action potential conduction in the AV node allows the atria to complete their contraction before action potentials are delivered to the ventricles • The AV bundle then divides into two branches of conducting tissue, called the left and right bundle branches PURKINJE FIBERS • At the tips of the left and right bundle branches • The Purkinje fibers pass to the apex of the heart and then extend to the cardiac muscle of the ventricle walls • Action potentials are more rapidly delivered to all the cardiac muscles of the ventricles ACTION POTENTIAL PATH THROUGH HEART 1. SA Node 2. AV node (Atrioventricular) 3. AV bundle 4. Right and Left Bundle branches 5. Purkinje Fibers 5 • • • • • ELECTROCARDIOGRAM (EKG or ECG) Used to monitor, check the functionality the status of the heart’s condition Record of electrical events in heart Diagnoses cardiac abnormalities Uses electrodes Contains P wave, QRS complex, T wave P WAVE • Depolarization of the atrial myocardium • The beginning of the P wave precedes the onset of atrial contraction. QRS COMPLEX • Depolarization of the ventricles • The beginning of the QRS complex precedes ventricular contraction. • The QRS complex consists of three individual waves: the Q, R, and S waves. T WAVE • Repolarization of the ventricles • The beginning of the T wave precedes ventricular relaxation • • • • CARDIAC CYCLE The cardiac cycle is the summative description of all the events that occur during one single heartbeat The heart is a two-sided pump with the atria being primers from pump, and the ventricle being the power pumps Cardiac muscle contraction produces pressure (from areas of higher pressure to areas of lower pressure) changes within the heart chambers The pressure changes are responsible for the movement of the blood DIASTOLE → As the chambers relax, they are filled with blood SYSTOLE → When the chambers contract, the blood is expelled ATRIAL SYSTOLE → Refers to contraction of the two atria VENTRICULAR SYSTOLE → Refers to contraction of the two ventricles ATRIAL DIASTOLE → Refers to relaxation of the two atria VENTRICULAR DIASTOLE → Refers to relaxation of the two ventricles HEART VALVE LOCATION The stethoscope is used to hear the heart sounds • There are two main heart sounds: → The first heart sound makes a lubb sound → The second heart sound makes dupp sound • The first heart sound is due to the closure of the Atrioventricular Valve • The second heart sound is due to the closure of the Semilunar Valve • 6 REGULATION OF THE HEART FUNCTION STROKE VOLUME → Volume of blood pumped per ventricle per contraction → 70 mL/beat HEART RATE → Number of heart beats in 1 min → 72 beats/min CARDIAC OUTPUT → Volume of blood pumped by a ventricle in 1 min → more than 5 L/min πΆπ = (ππΏ/min ) ππ × π»π (ππΏ/ππππ‘) (ππππ‘π /πππ) INTRINSIC REGULATION OF THE HEART Intrinsic regulation refers to the mechanisms contained within the heart itself that control cardiac output VENOUS RETURN → is the amount of blood that returns to the heart PRELOAD → Preload is the degree to which the ventricular walls are stretched at the end of diastole STARLING’S LAW OF THE HEART → The relationship between preload and stroke volume AFTER LOAD → refers to the pressure against which the ventricles must pump blood • • EXTRINSIC REGULATION OF THE HEART Extrinsic regulation refers to mechanisms external to the heart, such as either nervous or chemical regulation NERVOUS CONTROL • Occurs through a Sympathetic and Parasympathetic division of the Autonomic Nervous System • Influences of heart activity are carried through autonomic nervous system • Both sympathetic and parasympathetic nerve • fibers innervate the heart and have a major effect on the SA node BARORECEPTOR REFLEX • The baroreceptor reflex is a mechanism of the nervous system that plays an important role in regulating heart function • Baroreceptors are stretch receptors that monitor blood pressure in the aorta and in the wall of the internal carotid arteries, which carry blood to the brain • Changes in blood pressure result in changes in the stretch of the walls of these blood vessels—and changes in the frequency of action potentials produced by the baroreceptors. • The action potentials are transmitted along nerve fibers from the stretch receptors to the medulla oblongata of the brain CHEMORECEPTOR REFLEX • The chemoreceptor reflex involves chemical regulation of the heart • • • • • • Chemicals can affect heart rate and stroke volume Epinephrine and norepinephrine bind to receptor proteins on cardiac muscle and cause increased heart rate and stroke volume Excitement, anxiety, or anger can affect the cardioregulatory center, resulting in increased sympathetic stimulation of the heart and increased cardiac output Depression, on the other hand, can increase parasympathetic stimulation of the heart, causing a slight reduction in cardiac output The medulla oblongata of the brain also contains chemoreceptors that changes pH and CO2 levels It also involves K+, Na+, and Ca2+ in cardiac functions HEART DISEASE CORONARY ARTERY DISEASE • Due to decrease blood supply to the heart • Coronary arteries are narrowed for some reason MYOCARDIAL INFARCTION (HEART ATTACK) • Due to closure of one or more coronary arteries • Area(s) of cardiac muscle lacking adequate blood supply die and scars (infarct) HEART PROCEDURES ANGIOPLASTY • Procedure opens blocked blood vessels STENT • Structures inserted to keep vessels open 7 BYPASS • Procedure reroutes blood away from blocked arteries LABORATORY BLOOD VESSELS • Blood vessels outside the heart are divided into two classes: PULMONARY VESSELS • Which transport blood from the right ventricle of the heart through the lungs and back to the left atrium SYSTEMIC VESSELS • Which transport blood from the left ventricle of the heart through all parts of the body and back to the right atrium BLOOD VESSEL FUNCTIONS 1. Carries blood • Blood vessels carry blood from the heart to all the tissues of the body and back to the heart. 2. Exchanges nutrients, waste products, and gases with tissues • Nutrients and O2 diffuse from blood vessels to cells in essentially all areas of the body. Waste products and CO2 diffuse from the cells, where they are produced, to blood vessels. 3. Transports substances • Blood transports hormones, components of the immune system, molecules required for coagulation, enzymes, nutrients, gases, waste products, and other substances to and from all areas of the body. 4. Helps regulate blood pressure • The circulatory system and the heart work together to regulate blood pressure within a normal range. 5. Directs blood flow to the tissues • The circulatory system directs blood to tissues when increased blood flow is required to maintain homeostasis. BLOOD VESSELS STRUCTURES ARTERIES • Carry blood away from heart • Thick with a lot of elastic VEINS • Carry blood toward heart • Thin with less elastic CAPILLARIES • Exchange occurs between blood and tissue fluids BLOOD FLOW Blood flows from arteries into arterioles ο― Arterioles into capillaries ο― Capillaries into venules ο― Venules to small veins ο― Veins return to heart BLOOD VESSEL WALLS Blood vessel walls consist of three layers, or tunics TUNICA INTIMA • Innermost layer, consists of an endothelium composed of simple squamous epithelial cells TUNICA MEDIA • Middle layer, consists of smooth muscle cells with elastic and collagen fibers TUNICA ADVENTITIA • Outermost layer • is composed of dense connective tissue • • • • CAPILLARIES Blood flows from arterioles into capillaries Capillaries branch to form networks Capillary walls consist of endothelium which is a layer of simple squamous epithelium 8 • surrounded by delicate loose connective tissue. Blood flow is regulated by smooth muscle cells called precapillary sphincters PULMONARY TRUNK • Blood pump from right ventricle towards the right lung PULMONARY VEIN • The four Pulmonary Vein exit the lungs and carry oxygen-rich blood to the left atrium AORTA ASCENDING AORTA • Passes superiorly from the left ventricle • The right and left coronary arteries arise from the base of the ascending aorta and supply blood to the heart SYSTEMIC CIRCULATION VESSELS The systemic circulation carries blood from the left ventricle to the tissues of the body and back to the right atrium Oxygenated blood from the pulmonary veins passes from the left atrium into the left ventricle and from the left ventricle into the aorta. Arteries distribute blood from the aorta to all portions of the body AORTIC ARCH • Three major arteries, which carry blood to the head and upper limbs, originate from the aortic arch → The brachiocephalic artery → The left common carotid artery → The left subclavian artery • VEINS Blood flows from capillaries into venules and from venules into small veins • MEDIUM SIZED VEINS • Collect blood from small veins and deliver to large veins LARGE VEINS • Contain valves • • • • When the circulation is towards the heart (up), the valve will open and there will be no backflow because the valve will close after the passage of the blood DESCENDING AORTA • It extends through the thorax and abdomen to the upper margin of the pelvis. THORACIC AORTA • The part of the descending aorta that extends through the thorax to the diaphragm ABDOMINAL AORTA • Descending aorta that extends from the diaphragm to the point at which it divides into the two common iliac arteries PULMONARY CIRCULATION VESSELS Blood vessels that carries blood from the right ventricle of the heart to the lungs and back to the left atrium of the heart 9 RIGHT COMMON CAROTID ARTERY • Branches off brachiocephalic artery • Supplies blood to right side of head and neck RIGHT SUBCLAVIAN ARTERY • Branches off brachiocephalic artery • Supplies blood to right upper limbs ARTERIES ARTERIES OF THE HEAD & NECK BRANCHES OF AORTIC ARCH BRACHIOCEPHALIC ARTERY • The first vessel to branch from the aortic arch • Supplies blood to the right side of head and neck LEFT COMMON CAROTID ARTERY • Second branch off aortic arch • Supplies blood to the left side of head and neck LEFT SUBCLAVIAN ARTERY • Third branch off aortic arch • Supplies blood to left upper limbs • • • CEREBRAL ARTERIAL CIRCLE or CIRCLE OF WILLIS It consists of Anterior Cerebral Artery, Anterior Communicating Artery, Internal Carotid Artery, Posterior Communicating Artery, and Posterior Cerebral Artery These are the main branch or route of blood circulation within the nervous system If there are leakages, it will affect specific parts of the brain cerebrovascular accident or stroke ARTERIES OF THE UPPER LIMBS AXILLARY ARTERIES • Continuation of subclavian • Supply blood deep in clavicle BRACHIAL ARTERIES • Continuation of axillary • Where blood pressure measurements are taken ULNAR ARTERIES • Branch of brachial artery • Near elbow RADIAL ARTERIES • Branch of brachial artery • Supply blood to forearm and hand • Pulse pressure is taken ABDOMINAL AORTA BRANCHES CELIAC TRUNK ARTERIES • Supply blood to stomach, pancreas, spleen, liver, upper duodenum SUPERIOR MESENTERIC ARTERIES • Supply blood to small intestines and upper portion of colon INFERIOR MESENTERIC ARTERIES • Supply blood to colon RENAL ARTERIES • Supply blood to kidneys HEPATIC ARTERIES • Supply blood to liver TESTICULAR ARTERIES • Supply blood to testes OVARIAN ARTERIES • Supply blood to ovaries INFERIOR PHRENIC ARTERIES • Supply blood to diaphragm 10 LUMBAR ARTERIES • Supply blood to lumbar vertebra and back muscles ARTERIES OF PELVIS COMMON ILIAC ARTERIES • Branches from abdominal aorta • Divides into internal iliac arteries EXTERNAL ILIAC ARTERIES • Division of common iliac artery • Supply blood to lower limbs INTERNAL ILIAC ARTERIES • Division of common iliac • Supply blood to pelvic area ARTERIES OF THE LOWER LIMBS FEMORAL ARTERIES • Supply blood to thigh POPLITEAL ARTERIES • Supply blood to knee ANTERIOR AND POSTERIOR TIBIAL ARTERIES • Supply blood to leg and foot FIBULAR ARTERIES • Supply blood to lateral leg and foot VEINS SUPERIOR VENA CAVA • Returns blood from head, neck, thorax, and right upper limbs INFERIOR VENA CAVA • Returns blood from abdomen, pelvis, lower limbs • Empties into right atrium of heart CEPHALIC VEINS • Empty into axillary vein and basilic vein MEDIAN CUBITAL VEINS • Connects to cephalic vein • Near elbow VEINS OF THE HEAD AND NECK EXTERNAL JUGULAR VEIN • Drain blood from head and neck • empties into subclavian veins INTERNAL JUGULAR VEIN • Drain blood from brain, face, neck • Empty into subclavian veins SUBCLAVIAN VEINS • Forms brachiocephalic veins BRACHIOCEPHALIC VEINS • Join to form superior vena cava VEINS OF THE UPPER LIMBS BRACHIAL VEINS • Empty into axillary vein VEINS OF THE THORAX RIGHT AND LEFT BRACHIOCEPHALIC VEINS • Drain blood from thorax into superior vena cava AZYGOS VEINS • Drain blood from thorax into superior vena cava INTERNAL THORACIC VEINS • Empty into brachiocephalic veins POSTERIOR INTERCOSTAL VEINS • Drain blood from posterior thoracic wall • Drains into azygos vein on right side HEMIAZYGOS VEIN • Receives blood from azygos vein of left side VEINS OF THE ABDOMEN AND PELVIS COMMON ILIAC VEIN • Formed from external and internal iliacs • Empty into inferior vena cava EXTERNAL ILIAC VEIN • Drains blood from lower limbs • Empty into common iliac vein INTERNAL ILIAC VEIN • Drains blood from pelvic region • Empties into common iliac vein RENAL VEIN • Drains blood from kidneys 11 VEINS OF THE LOWER LIMBS FEMORAL VEINS • Drain blood from thigh and empty into external iliac vein GREAT SAPHENOUS VEINS • Drain from foot and empty into femoral vein POPLITEAL VEINS • Drain blood from knee and empty into femoral vein HEPATIC PORTAL SYSTEM The liver is a major processing center for substances absorbed by the intestinal tract. • As such, blood from the capillaries within most of the abdominal viscera, such as the stomach, intestines, pancreas, and spleen, drains through a specialized portal system to the liver. PORTAL SYSTEM • Vascular system that begins with capillaries in viscera and ends with capillaries in liver • Uses splenic vein and superior mesenteric vein • • BLOOD PRESSURE Blood pressure is a measure of the force blood exerts against the blood vessel walls. • • SYSTOLIC PRESSURE • Contraction of the heart • Good determinants about organ perfusion DIASTOLIC PRESSURE • Relaxation of heart AVERAGE BLOOD PRESSURE • 120/80 • Systolic Pressure – Good determinants about organ perfusion • Organ Perfusion – How the organ receives the needed nutrients and electrolytes for them to be sustained BODY LOCATIONS TO EVALUATE PULSES • • • • • • • PULSE PRESSURE The difference between the systolic and diastolic pressures Example – 120 for systolic/ 80 for diastolic; pulse pressure is 40 mm Hg Pulse pressure points can be felt near large arteries Formula: • • Superficial Temporal artery Common carotid artery Facial artery Axillary artery Brachial artery • • • • • Radial artery Femoral artery Popliteal artery Dorsalis pedis artery Posterior tibial artery LOCAL CONTROL OF BLOOD FLOW THROUGH CAPILLARY BEDS Achieved by the periodic relaxation and contraction of the precapillary sphincters When the sphincters relax, blood flow through the capillaries increases 12 • • • The precapillary sphincters are controlled by the metabolic needs of the tissues At concentration of nutrients also control blood flow When there is a decreased level of oxygen in the blood, blood flow increases, there is a protective mechanism of the body (higher centers of the brain) will be activated/help just to ensure that adequate nutrients will be transported to the very vital organs of the body. Through this mechanism, blood flow will increase NERVOUS CONTROL OF BLOOD FLOW VASOMOTER CENTER • Sympathetic Division of the nervous system • When there is a change in the diameter of the blood vessels, this is initiated by the sympathetic division • Controls blood vessel diameter VASOMOTOR TONE • State of partial constriction of blood vessels • Increase causes blood vessels to constrict and blood pressure to go up • • • • • • HORMONAL CONTROL OF BLOOD FLOW • The sympathetic division also regulates hormonal control blood flow through the release of epinephrine and norepinephrine from the adrenal medulla • The epinephrine and norepinephrine are part of the neurotransmitters, and in most blood vessels, these hormones close constrictions which reduces the blood flow • In some tissues, such as skeletal muscle and cardiac muscle, these hormones can cause the blood vessels to dilate, thus, increasing the blood flow • • • MEAN ARTERIAL PRESSURE Mean arterial pressure (MAP) is a calculated value that reflects an average arterial pressure in various vessels of the body The body’s MAP is equal to the cardiac output (CO) times the peripheral resistance (PR) ππ΄π = πΆπ × ππ Peripheral Resistance – Resistance of blood flow in the blood vessels Or MAP changes in response to Heart Rate, Stroke Volume or Peripheral Resistance MAP is about 70 mm Hg at birth It is maintained at about 95 mm Hg from adolescence to middle age, and may reach 110 mm Hg in a healthy older person 60 mm Hg (lowest but acceptable) Normal – 70-100 mm Hg MAP is the following formula: ππ΅π + 2(π·π΅π) ππ΄π = 3 1 ππ΄π = (ππ΅π − π·π΅π) + π·π΅π 3 SBP – Systolic Pressure DBP – Diastolic Pressure • • • • MAP is important as it determines the blood circulation in a specific tissue or organs MAP is for the doctor to determine how much blood the organs or tissues received Mean Arterial Pressure is significant because it measures the pressure necessary to adequate perfusion of the organs of the body Tissue Perfusion is the means by which blood provides nutrients and removes cellular waste EXAMPLE Blood pressure: 106/70 πππ»π (106)+2 (70) ππ΅π+2 (π·π΅π) Formula: = 3 3 (106) + 140 246 = = 82 ππ π»π 3 3 13 Blood pressure: 106/70 ππ π»π 1 Formula: ππ΄π = (ππ΅π − π·π΅π) + π·π΅π 3 1 1 ππ΄π = (106 − 70) + 70 = (36) + 70 3 3 ππ΄π = 12 + 70 = 82 ππ π»π BARORECEPTOR REFLEXES • Baroreceptor reflexes activate responses that keep the blood pressure within its normal range • Baroreceptors respond to stretch in arteries caused by increased pressure • Located in the Carotid Sinus and Aortic Arch • Change in Peripheral Resistance, Heart Rate, Stroke Volume are in response to blood pressure, it stimulates the sensory nerves to conduct an action potential to the regulatory end (Motor centers of the Medulla Oblongata) • Increase in the Parasympathetic stimulation of the heart could decrease the heart rate • Increase in the Sympathetic Stimulation of the heart could increase the heart rate, stroke volume, and vasoconstriction • • • • • • CHEMORECEPTOR REFLEX Chemoreceptors are sensitive to change in blood oxygen, Carbon dioxide and pH. Located in Carotid Bodies and Aortic Bodies, which lie near the carotid sinuses, and the aortic arch respectively Action potential along the with nerve fiber to the Medulla Oblongata If there is a decrease in the level of oxygen, an increase CO2 level, and a decrease in blood pH, a decrease of the Parasympathetic stimulation of the heart which increases the heart rate If there is a decrease in the level of oxygen, an increase CO2 level, and a decrease in blood pH, an increase of the Sympathetic stimulation of the heart which increases the heart rate and stroke volume These decreased blood oxygen level, increased CO2 level, and decreased blood pH, increases Sympathetic Stimulation of the blood vessel which increases vasoconstriction • • • • • • • ADRENAL MEDULLARY MECHANISM Stimuli that increase Sympathetic Stimulation of the heart and blood vessels causes action potential to be carried to the Medulla Oblongata This also increases the Sympathetic Stimulation of the Adrenal Medulla; thus, the Adrenal Medulla secretes the neurotransmitters epinephrine and norepinephrine into the blood, it will then cause increased heart rate, stroke volume and vasoconstriction For the Cardiac and Skeletal muscles, this could cause vasodilation of the blood vessels RENIN-ANGIOTENSIN-ALDOSTERONE MECHANISM A reduced blood flow causes kidneys to release Renin, into the circulatory system Renin acts on the blood protein angiotensinogen to produce angiotensin I Another enzyme, called angiotensinconverting enzyme (ACE), found in lungs, acts on angiotensin I to convert it to its most active form, angiotensin II Angiotensin II is a potent vasoconstrictor 14 • • • Angiotensin II also acts on the adrenal cortex to increase the secretion of aldosterone Aldosterone acts on the kidneys, causing them to conserve Na+ and water As a result, there is less water lost in the urine and the blood pressure is maintained ANTIDIURETIC HORMONE MECHANISM • The nerve cells in the hypothalamus releases antidiuretic hormone or ADH • when concentration of solutes in plasma increases, or when there is a decrease in blood pressure • ADH acts on the kidneys and absorb more water, thus, it decreases urine volume, as a result, maintain blood volume and pressure • ATRIAL NATRIURETIC MECHANISM An elevation blood pressure causes the release peptide hormone found in the right atrium of the heart Elevated Blood pressure causes the release of peptide hormone ο― Causes kidney to promote sodium loss and water in the urine ο― Loss of water in the urine cause a blood volume to decrease ο― Blood pressure decrease AGING AND BLOOD VESSELS ARTERIOSCLEROSIS • Makes arteries less elastic ATHEROSCLEROSIS • Type of arteriosclerosis • From deposit of materials in artery walls (plaque) FACTORS THAT CONTRIBUTE TO ATHEROSCLEROSIS • Lack of exercise, smoking, obesity, diet high in cholesterol and trans fats, some genetics • HYPERTENSION Or high blood pressure, affects at least 20% of all people at some time in their lives. The following guidelines* categorize blood pressure for adults: → Normal: less than 120 mm Hg systolic and 80 mm Hg diastolic → Prehypertension: from 120 mm Hg systolic and 80 mm Hg diastolic to 139 mm Hg systolic and 89 mm Hg diastolic → Stage 1 hypertension: from 140 mm Hg systolic and 90 mm Hg diastolic to 159 mm Hg systolic and 99 mm Hg diastolic → Stage 2 hypertension: greater than 160 mm Hg systolic and 100 mm Hg diastolic 15 • • • • • DIGESTIVE SYSTEM Digestion is the breakdown of large organic molecules into smaller molecules that can be absorbed. The digestive system performs the task of digestion. Food is taken into the digestive system, where it is enzymatically broken down into smaller and smaller particles for absorption. The small intestine is the work course of the system where the majority of the digestion occurs and where most of the released nutrients are absorbed into the blood Each of the digestive system organ make a vital contribution to this process DIGESTIVE SYSTEM FUNCTIONS 1. Ingestion of solids and liquids • Ingestion is the consumption of solid or liquid food, usually through the mouth 2. Digestion of organic molecules • Digestion is the breakdown of large organic molecules into smaller molecules that can be absorbed. Digestion occurs through mechanical and chemical means. 3. Absorption of nutrients • Absorption is the movement of molecules out of the digestive tract and into the blood or lymphatic system. The epithelial cells that line the lumen of the small intestine absorb the small molecules of nutrients (amino acids, monosaccharides, fatty acids, vitamins, minerals, and water) that result from the digestive process. 4. Elimination of waste • Elimination is the removal of undigested material, such as fiber from food, plus other waste products from the body as feces. DIGESTIVE SYSTEM • All digestive organs play an integral role in the life sustaining process of digestion • Like other body systems, the digestive system does not work in isolation, it functions cooperatively with the other systems of the body • Example: → The interrelationship between the digestive and cardiovascular systems β’ The arteries supply the digestive organs with oxygen and processed nutrients, and veins drain the digestive tract β’ These intestinal veins constituting the hepatic portal system are unique, they do not return blood supplies directly to the heart, but, these blood is diverted to the liver where nutrients are off loaded for processing before blood completes its circulation to the heart β’ The digestive nutrients provide nutrients to the heart muscle and muscular tissues to support their function → The interrelationship between the digestive and endocrine system β’ Hormones secreted by several endocrine glands and cells of the pancreas, the stomach and small intestine contribute to the control of digestion and nutrient metabolism β’ The digestive system provides the nutrients to fuel endocrine function CONTRIBUTION OF OTHER BODY SYSTEM TO THE DIGESTIVE TRACT 16 DIGESTIVE SYSTEM The digestive system consists of the digestive tract, plus specific associated organs. The digestive tract is also referred to as the GI (gastrointestinal tract) The tract is one long tube from the mouth to the anus. • DIGESTIVE TRACT COMPONENTS The digestive tract consists of the: Organs that make up the Alimentary Canal 1. Oral cavity (mouth) 2. Pharynx 3. Esophagus 4. Stomach 5. Small intestines 6. Large intestines 7. Rectum 8. Anus • • ASSOCIATED ORGANS Second accessory organs Critical for the breakdown of foods, and the assimilation of its nutrients into the body The digestive system includes some associated organs not directly in the digestive tract, but have ducts that lead into the tract. These associated organs are the: 1. Salivary glands 2. Liver 3. Gallbladder 4. Pancreas • • • • • LAYERS THE DIGESTIVE TRACT WALL The layers of the tract wall are also termed tunics MUCOSA • Innermost layer • Secretes mucus SUBMUCOSA • Above mucosa • Contains blood vessels, nerves, small glands MUSCULARIS • Above submucosa • Longitudinal – outer layer • Circular – inner layer • Oblique muscles • Together, the nerve plexuses of the submucosa and muscularis compose the enteric nervous system which is a division of the autonomic nervous system, is extremely important in controlling movement and secretion within the tract SEROSA/ADENTITIA • Outermost layer • Peritoneum is present called serosa - a smooth epithelial layer, and its underlying connective tissue • No peritoneum then called adventitia – are covered by a connective tissue layer which is continuous with the surrounding connective tissue. DIGESTIVE TRACT HISTOLOGY → Has 4 tunic or layers 1. Mucosa • Mucous Epithelium • Lamina Propia • Muscularis Mucosae 2. Submucosa 3. Muscularis • Circular Smooth Muscle • Longitudinal Smooth Muscle 4. Serosa and Adventitia • Serosa – covers peritoneum • Adventitia – does not cover peritoneum PERITONEUM → The walls of the abdominal cavity and the abdominal organs are associated with a serous membrane → The serous membrane that covers the organs is the visceral peritoneum, or serosa. → The serous membrane that lines the wall of the abdominal cavity is the parietal peritoneum. → Layer of smooth epithelial tissue 17 MESENTERIES • Connective tissue of organs in abdominal cavity • Provide a route for blood vessels and nerves from the abdominal wall to the organs LESSER OMENTUM • Mesentery connecting lesser curvature of stomach to liver and diaphragm GREATER OMENTUM • Mesentery connecting greater curvature of stomach to transverse colon and posterior body wall OMENTAL BURSA • greater omentum is unusual in that it is a long, double fold of mesentery that extends inferiorly from the stomach before looping back to the transverse colon to create a cavity, or pocket • Adipose tissue accumulates in the greater omentum, giving it the appearance of a fat-filled apron that covers the anterior surface of the abdominal viscera • • • ORAL CAVITY First part of digestive system Contains stratified squamous epithelia It is bounded by the lips and cheeks and contains the teeth and tongue. LIPS • The lips are muscular structures, formed mostly by the orbicularis oris muscle CHEEKS • The cheeks form the lateral walls of the oral cavity. Located within the cheeks are the buccinator muscles → The lips and cheeks are important in the process of mastication, or chewing → Begins the process of mechanical digestion, which breaks down large food particles into smaller ones TONGUE • The tongue is a large, muscular organ that occupies most of the oral cavity SALIVARY GLANDS • Produce saliva which contains enzymes to breakdown carbohydrates into glucose • Cleanse mouth • Dissolve and moisten food AMYLASE • Salivary enzyme that breaks down carbohydrates LYSOZYME • Salivary enzymes that are active against bacteria TONGUE • House taste buds and mucus TEETH • 32 teeth in normal adult → Incisors - one central and one lateral → Canine - one → Premolars - first and second → Molars - first, second, and third → Wisdom – third molars → Permanent Teeth or Secondary Teeth • 20 primary teeth (baby teeth) • Each tooth has regions → Crown → Cusp → Neck → Root PULP CAVITY • Center of tooth is pulp cavity → Pulp – filled with blood vessels, nerves, and connective tissue → Dentin – pulp cavity is surrounded by a living, cellular, calcified tissue ENAMEL • is hard covering protects against abrasions 18 • dentin of the tooth crown is covered by an extremely hard, acellular substance • Cavities are breakdown of enamel by acids from bacteria CEMENTUM • surface of the dentin in the root is covered, which helps anchor the tooth in the jaw DENTAL CARIES OR TOOTH DECAY • is the result of the breakdown of enamel by acids produced by bacteria on the tooth surface MOLAR TOOTH IN PLACE IN THE ALVEOLAR BONE • • (a) Permanent teeth (b) Deciduous teeth • Dental professionals have developed a “universal” numbering and lettering system for convenience in identifying individual teeth A tooth consists of a crown, a neck, and a root. The root is covered with cementum, and the tooth is held in the socket by periodontal ligaments. Nerves and vessels enter and exit the tooth through a foramen in the part of the root deepest in the alveolus. PALATE • Roof of oral cavity • Separates the oral cavity from the nasal cavity • Prevents food from passing into the nasal cavity during chewing and swallowing HARD PALATE • Anterior part contains bone SOFT PALATE • Posterior part consists of skeletal muscle and connective tissue TONSILS • Located in the lateral posterior walls of the oral cavity, in the nasopharynx, and in the posterior surface of the tongue SALIVARY GLANDS Includes submandibular, sublingual, parotid glands • Produce saliva contains enzymes to breakdown food • Mumps is inflammation of parotid gland. The inflamed parotid glands become swollen, often making the cheeks quite large. PAROTID GLANDS • The largest of the salivary glands • Are serous glands located just anterior to each ear SUBMANDIBULAR GLANDS • produce more serous than mucous secretions SUBLINGUAL GLANDS • The smallest salivary glands • Produce primarily mucous secretions • PHARYNX • • • Throat Connects the mouth to the esophagus It has three parts: 1. Nasopharynx 2. Oropharynx 3. Laryngopharynx 19 • • • • • Normally, only the oropharynx and laryngopharynx carry food to the esophagus. The posterior walls of the oropharynx and laryngopharynx are formed by the superior, middle, and inferior pharyngeal constrictor muscles. ESOPHAGUS Tube that connects the pharynx to the stomach Transports food to the stomach Joins stomach at cardiac opening ESOPHAGEAL SPHINCTERS • regulate the movement of food into and out of the esophagus CARDIAC SPHINCTER • lower esophageal sphincter HEARTBURN • Occurs when gastric juices regurgitate into esophagus • Caused by caffeine, smoking, or eating or drinking in excess SWALLOWING OR DEGLUTITION VOLUNTARY PHASE • bolus (mass of food) formed in mouth and pushed into oropharynx • The tongue pushes the bolus against the hard palate PHARYNGEAL PHASE • Swallowing reflex initiated when bolus stimulates receptors in oropharynx ESOPHAGEAL PHASE • Moves food from pharynx to stomach PERISTALSIS • Wave like contractions moves food through digestive tract • As food passes through the pharynx, the vestibular and vocal folds close, and the epiglottis is tipped posteriorly, so that the opening into the larynx is covered • • • • • • PERISTALSIS Waves of smooth muscle contraction push digesting food and waste through the digestive tract. STOMACH Located in abdomen Storage tank for food Can hold up to 2 liters of food Produces mucus, hydrochloric acid, protein digesting enzymes Contains a thick mucus layer that lubricates and protects epithelial cells on stomach wall form acidic pH (3) 3 MUSCULAR LAYERS • outer longitudinal, middle circular, and inner oblique to produce churning action RUGAE • Large folds that allow stomach to stretch CHYME • Paste-like substance that forms when food begins to be broken down PYLORIC OPENING • Opening between stomach and small intestine PYLORIC SPHINCTER • Thick, ring of smooth muscle around pyloric opening HUNGER PANGS • Stomach is stimulated to contract by low blood glucose levels usually 12-24 hours after a meal 20 ANATOMY AND HISTOLOGY OF THE STOMACH • • • • • • THREE PHASES OF GASTRIC SECRETION • • REGULATION OF STOMACH SECRETIONS • Parasympathetic stimulation, gastrin, histamine increase stomach secretions Cephalic phase, Gastric Phase, and Intestinal Phase During each phase, the secretion of Gastric Juice can be stimulated or inhibited CEPHALIC PHASE OR REFLEX PHASE 1st phase Relatively brief Takes place before enters the stomach The smell, taste, sight, or thoughts of food triggers this phase → e.g. when you bring a piece of sushi to the lips, impulses from receptors in the taste buds or the nose are relayed to the brain → which returns signals that increase gastric secretion to prepare stomach for digestion This enhanced condition is also called condition reflex – occurs only if you like or want a particular food Depression and lost of Appetite can suppress the Cephalic Reflex GASTRIC PHASE OF SECRETION • 2nd Phase • Partially digested proteins and distention of stomach promote secretion • Last for 3-4 hours • It is set it in motion by local neural and hormonal mechanisms triggered by entry of food into the stomach → e.g. when the sushi reaches the stomach, it creates this tension that activates the stretch receptor → these stimulates parasympathetic neurons to release acetylcholine which then provokes increase secretion of gastric juice • Partially digested proteins, caffeine, and rising pH stimulate the release of Gastrin, from enteroendocrine cells (G cells), which in return induces parietal cells to increase the production of Hydrochloric Acid • Hydrochloric acid is needed to create an acidic environment for the conversion of Pepsinogen to Pepsin and Protein Digestion • The release of Gastrin activates vigorous smooth muscle contractions • However, the stomach does have the natural means of avoiding excessive acid secretion and potential heart burn • When pH levels drop too low, cells in the stomach react by suspending hydrochloric acid secretion and increasing mucus secretion 21 SMALL INTESTINE Measures 6 meters in length Major absorptive organ Chyme takes 3 to 5 hours to pass through Contains enzymes to further breakdown food • Contains secretions for protection against the acidity of chyme • Consists of three parts: Duodenum, Jejunum, and Ileum DUODENUM • First part • 25 cm long • Contains absorptive cells, goblet cells, granular cells, endocrine cells • Contains microvilli and many folds • Contains bile and pancreatic ducts JEJUNUM • Second part • meters long and absorbs nutrients ILEUM • Third part • 3.5 meters long • • • • INTESTINAL PHASE OF SECRETION • 3rd phase • Acidic chyme stimulates neuronal reflexes and secretions of hormones that inhibit gastric secretions by negative feedback loops • Has excitatory and inhibitory elements • The duodenum has a major role in regulating the stomach and its emptying • When partially digested food feels the duodenum, intestinal mucosa cells release a hormone called intestinal or enteric gastrin which further excites gastric juice secretion • This stimulatory activity is brief, however, because when the intestine distends with chyme, the enterogastric reflex inhibits secretion • One of the effects of this reflex is to close the pyloric sphincter, which blocks additional chyme from entering the duodenum MOVEMENT IN STOMACH MIXING WAVES • Weak contraction • Thoroughly mix food to form chyme PERISTALTIC WAVES • Stronger contraction • Force chyme toward and through pyloric sphincter → Hormonal and neural mechanisms stimulate stomach secretions → Stomach empties every 4 hours after regular meal, and 6 to 8 hours after high fatty meal 22 • MUCOSA OF THE SMALL INTESTINE The mucosa of the small intestine is simple columnar epithelium with four major cell types. 1. Absorptive cells, which have microvilli, produce digestive enzymes, and absorb digested food 2. Goblet cells, which produce a protective mucus 3. Granular cells, which may help protect the intestinal epithelium from bacteria 4. Endocrine cells, which produce regulatory hormones. INTESTINAL GLANDS • The epithelial cells are located within tubular glands of the mucosa, called intestinal glands or crypts of Lieberkühn, at the base of the villi. • Granular and endocrine cells are located in the bottom of the glands. • The submucosa of the duodenum contains mucous glands, called duodenal glands, which open into the base of the intestinal glands. SECRETIONS OF THE SMALL INTESTINE • The epithelial cells in the walls of the small intestine have enzymes bound to their free surfaces • Peptidases enzymatically breakdown proteins into amino acids for absorption • Disaccharidases enzymatically breakdown disaccharides into monosaccharides for absorption. ANATOMY AND HISTOLOGY OF THE DUODENUM → The ileocecal valve prevents movement from the large intestine back into the ileum. SEGMENTAL CONTRACTIONS IN THE SMALL INTESTINE • • MOVEMENT IN THE SMALL INTESTINE → Mixing and propulsion of chyme are the primary mechanical events that occur in the small intestine. PERISTALTIC CONTRACTIONS • Proceed along the length of the intestine for variable distances and cause the chyme to move along the small intestine. SEGMENTAL CONTRACTIONS • Are propagated for only short distances and mix intestinal contents. → The ileocecal sphincter at the juncture of the ileum and the large intestine remains mildly contracted most of the time. → Peristaltic contractions reaching the ileocecal sphincter from the small intestine cause the sphincter to relax and allow chyme to move from the small intestine into the cecum. • • • • • • • LIVER The liver processes nutrients and detoxifies harmful substances from the blood It produces an important digestive fluid called bile Largest internal organ of the body and weighs about 1.36 kg Located in the right upper quadrant of the abdomen under the diaphragm The posterior surface of the liver is in contact with right ribs 5-12. The liver consists of two major lobes, the right lobe and the left lobe. The two lobes are separated by a connective tissue septum, called the falciform ligament. Two smaller liver lobes, the caudate lobe and the quadrate lobe Consists of right, left, caudate, and quadrate lobes 23 PORTA • Gate where blood vessels, ducts, nerves enter and exit • Receives arterial blood from the hepatic artery HEPATIC ARTERY • Delivers oxygenated blood to the liver, which supplies liver cells with oxygen HEPATIC PORTAL VEIN • Carries nutrient-rich blood from the digestive tract to the liver HEPATIC VEINS • Where blood exits the liver and empties into the inferior vena cava LOBULES • Divisions of liver with portal triads at corners PORTAL TRIAD • Contain hepatic artery, hepatic portal vein, hepatic duct HEPATIC CORDS • Between center margins of each lobule • Formed by platelike groups of liver cells called hepatocytes • Separated by hepatic sinusoids HEPATIC SINUSOIDS • Contain phagocytic cells that remove foreign particles from blood CENTRAL VEIN • Center of each lobule • Where mixed blood flows towards • Forms hepatic veins • The central veins from all the lobes unite to form the hepatic veins, which carry blood out of the liver to the inferior vena cava. BILE CANALICULUS • is a cleftlike lumen between the cells of each hepatic cord. LIVER DUCTS HEPATIC DUCT • Transport bile out of liver COMMON HEPATIC DUCT • Formed from left and right hepatic duct GALLBLADDER • Small sac on the inferior surface of the liver that stores concentrated bile CYSTIC DUCT • Joins common hepatic duct • From gallbladder COMMON BILE DUCT • Formed from common hepatic duct and cystic duct • The common bile duct joins the pancreatic duct DUODENAL PAPILLA • They open into the duodenum • A sphincter regulates the opening into the duodenum BILE AND PANCREATIC SECRETIONS 1. The hepatic ducts from the liver lobes combine to form the common hepatic duct. 2. The common hepatic duct combines with the cystic duct from the gallbladder to form the common bile duct. 3. The common bile duct joins the pancreatic duct. 4. The combined duct empties into the duodenum at the duodenal papilla. 5. Pancreatic secretions may also enter the duodenum through an accessory pancreatic duct, which also empties into the duodenum. 24 FUNCTIONS OF THE LIVER • Digestive and excretory functions • Stores and processes nutrients • Detoxifies harmful chemicals • Synthesizes new molecules • Secretes 700 milliliters of bile each day BILE → dilutes and neutralizes stomach acid and breaks down fats → liver produces and secretes about 600– 1000 mL of bile each day. BILE SALTS → Emulsify fats, breaking the fat globules into smaller droplets • • • • CONTROL OF BILE SECRETION AND RELEASE • • • • • • PANCREAS Located posterior to stomach in inferior part of left upper quadrant Head near midline of body Tail extends to left and touches spleen • • DUODENUM AND PANCREAS Endocrine tissues have pancreatic islets that produce insulin and glucagon Exocrine tissues produce digestive enzymes that travel through ducts FUNCTIONS OF THE PANCREAS The exocrine secretions of the pancreas include bicarbonate ions (HCO3−), and digestive enzymes, called pancreatic enzymes. Bicarbonate ions neutralize the acidic chyme that enters the small intestine from the stomach. The increased pH resulting from the secretion of HCO3− stops pepsin digestion but provides the proper environment for the function of pancreatic enzymes. Without pancreatic enzymes, lipids, proteins, and carbohydrates cannot be adequately digested PANCREATIC SECRETIONS The major protein digesting enzymes are: → Trypsin → Chymotrypsin → Carboxypeptidase Pancreatic amylase continues the polysaccharide digestion that began in the oral cavity. The pancreatic enzyme lipase, a lipid digesting enzyme. The pancreatic nuclease enzymes degrade DNA and RNA to their component nucleotides. • The head of the pancreas lies within the duodenal curvature, with the pancreatic duct emptying into the duodenum. CONTROL OF PANCREATIC SECRETION • Cholecystokinin and parasympathetic impulses stimulate pancreatic enzyme secretion. Secretin stimulates secretion of bicarbonate from the pancreas. 25 • • • LARGE INTESTINE 18–24 hours are required for material to pass through the large intestine, in contrast to the 3–5 hours required for chyme to move through the small intestine Chyme is converted to feces The colon stores the feces until they are eliminated by the process of defecation CECUM • The cecum is the proximal end of the large intestine where it joins with the small intestine at the ileocecal junction. • Appendix – attached to the Cecum, which is a 9 cm long, it is often removed once inflamed or Appendicitis COLON • The colon is about 1.5-1.8 m long and consists of four parts: (1) the ascending colon, (2) the transverse colon, (3) the descending colon, and (4) the sigmoid colon → Ascending colon – extends superiorly from the cecum to the right colic flexure, near the liver, where it turns to the left → Transverse colon – extends from the right colic flexure to the left colic flexure near the spleen, where the colon turns inferiorly → Descending colon – extends from the left colic flexure to the pelvis, where it becomes the sigmoid colon. → Sigmoid colon – forms an S-shaped tube that extends medially and then inferiorly into the pelvic cavity and ends at the rectum. RECTUM • The rectum is a straight, muscular tube that begins at the termination of the sigmoid colon and ends at the anal canal • The muscular tunic is composed of smooth Muscle and is relatively thick in the rectum compared to the rest of the digestive tract. ANAL CANAL • The last 2–3 cm of the digestive tract • It begins at the inferior end of the rectum and ends at the anus (external digestive tract opening). • The smooth muscle layer of the anal canal is even thicker than that of the rectum and forms the internal anal sphincter at its superior end. • The external anal sphincter at the inferior end of the anal canal is formed by skeletal muscle. DIGESTIVE PROCESS 1. Digestion • Breakdown of food occurs in stomach and mouth • Mechanical digestion – breaks large food particles into smaller ones • Chemical digestion – uses enzymes to break covalent chemical bonds in organic molecules 2. Propulsion • Moves food through digestive tract includes swallowing and peristalsis 3. Absorption • Primarily in duodenum and jejunum of small intestine 4. Defecation • Elimination of waste in the form of feces DIGESTION • Food consists primarily of carbohydrates, lipids and proteins → Carbohydrates are broken down into Monosaccharides → Lipids are broken down into fatty acids and monoglycerides → Proteins are broken down into Amino Acids 26 DIGESTION OF CARBOHYDRATES, LIPIDS, AND PROTEINS • The enzymes involved in digesting carbohydrates, lipids, and proteins are depicted in relation to the region of the digestive tract where each functions. CARBOHYDRATE DIGESITON • Polysaccharides split into disaccharides by Salivary and Pancreatic Amylase • Disaccharides are broken down into monosaccharides by disaccharides on the surface of the intestinal epithelium • Glucose is absorb by cotransport with sodium into the intestinal epithelium • Glucose is carried by the hepatic portal vein to the liver and enters most cells by facilitated diffusion TRANSPORT OF GLUCOSE ACROSS THE INTESTINAL EPITHELIUM TRANSPORT OF LIPIDS ACROSS THE INTESTINAL EPITHELIUM LIPID DIGESTION • Lipase breaks down triglycerides into fatty acids and monoglycerides. • Bile salts surround fatty acids and monoglycerides to form micelles. • Micelles attach to the plasma membranes of intestinal epithelial cells, and the fatty acids and monoglycerides pass by simple diffusion into the intestinal epithelial cells. • Within the intestinal epithelial cell, the fatty acids and monoglycerides are converted to triglycerides. • Proteins coat the triglycerides to form chylomicrons, which move out of the intestinal epithelial cells by exocytosis. • The chylomicrons enter the lacteals of the intestinal villi and are carried through the lymphatic system to the blood. LIPOPROTEINS • Lipids are packaged into lipoproteins to allow transport in the lymph and blood. • Lipoproteins are molecules that are part water soluble and part lipid soluble. • Since lymph and blood contain water and lipids are not water soluble, lipoproteins are necessary for transport. • Lipoproteins include chylomicrons, lowdensity lipoproteins (LDL), and high-density lipoproteins (HDL). • Cholesterol and fat are transported through the blood by lipoproteins. 27 PROTEIN DIGESTION • Pepsin is a protein-digesting enzyme secreted by the stomach. • The pancreas secretes trypsin, chymotrypsin, and carboxypeptidase into the small intestine in an inactive state. • In the small intestines these enzymes are activated. • In the small intestine, other enzymes termed peptidases, bound to the microvilli of the intestinal epithelium further break down small peptides into tripeptides. • Absorption of tripeptides, dipeptides, or individual amino acids occurs through the intestinal epithelial cells by various cotransport mechanisms. • • • The movement depends on osmotic pressures 99% of water entering intestine is absorbed Minerals are actively transported across wall of small intestine FLUID VOLUMES IN THE DIGESTIVE TRACT TRANSPORT OF AMINO ACIDS ACROSS THE INTESTINAL EPITHELIUM WATER AND MINERALS • We ingest about 2 L in food and drink • Approximately 92% of that water is absorbed in the small intestine, about 7% is absorbed in the large intestine, and about 1% leaves the body in the feces • Water can move across the intestinal wall in either direction • Fluid movement across the digestive tract varies depending on the particular segment. 28 RESPIRATORY SYSTEM • Respiration includes the following processes: → First ventilation or breathing which is the movement of air into and out of the lungs → Second the exchange of oxygen and carbon dioxide between the air in the lungs and the blood third the transport of oxygen and carbon dioxide in the blood → Lastly, the exchange of oxygen and carbon dioxide between the blood and the tissues FUNCTIONS OF THE RESPIRATORY 1. Respiration → Can be confusing to hear that term alone because sometimes it also refers to cellular metabolism or cellular respiration → The two processes are directly related → Breathing provides oxygen needed in cellular respiration to make an ATP from glucose and breathing also reads the body of potentially toxic carbon dioxide 2. Regulation of blood pH → The respiratory system can alter blood pH by changing blood CO2 levels. 3. Voice Production → Air movement past the vocal cords makes sound and speech possible. 4. Olfaction → The sensation of smell occurs when airborne molecules are drawn into the nasal cavity 5. Innate Immunity → The respiratory system protects against some microorganisms and other pathogens, such as viruses, by preventing them from entering the body and by removing them from respiratory surfaces. RESPIRATORY SYSTEM • The respiratory system has two divisions: the upper respiratory tract and the lower respiratory tract UPPER RESPIRATORY TRACT → Includes the nose, the pharynx (throat) and the larynx. LOWER RESPIRATORY TRACT → Includes the trachea, the bronchi, and the lungs. • Keep in mind, however, that upper and lower respiratory tract are not official anatomical terms. Rather, they are arbitrary divisions for the purposes of discussion, and some anatomists define them differently. • Even though air frequently passes through the oral cavity, the oral cavity is considered part of the digestive system, not the respiratory system. NOSE • Consists of the external nose and the nasal cavity EXTERNAL NOSE • Is the visible structure that forms a prominent feature of the face. • Most of the external nose is composed of hyaline cartilage, although the bridge of the external nose consists of bone • The bone and cartilage are covered by connective tissue and skin NARES/NOSTRILS • The external openings of the nose CHOANAE/FUNNELS • The openings into the pharynx 29 NASAL CAVITY • Extends from the nares to the choanae NASAL SEPTUM • Partition dividing the nasal cavity into right and left parts. DEVIATED NASAL SEPTUM • Occurs when the septum bulges to one side HARD PALATE • Forms the floor of the nasal cavity, separating the nasal cavity from the oral cavity. • Air can flow through the nasal cavity when the oral cavity is closed or full of food. CONCHAE • Three prominent bony ridges are present on the lateral walls on each side of the nasal cavity. • The conchae increase the surface area of the nasal cavity and cause air to churn, so that it can be cleansed, humidified, and warmed. • PARANASAL SINUSES • Are air-filled spaces within bone. • They include the maxillary, frontal, ethmoidal, and sphenoidal sinuses, each named for the bones in which they are located. • The paranasal sinuses open into the nasal cavity and are lined with a mucous membrane. They reduce the weight of the skull, produce mucus, and influence the quality of the voice by acting as resonating chambers NASOLACRIMAL DUCTS • Which carry tears from the eyes, also open into the nasal cavity. • Sensory receptors for the sense of smell are in the superior part of the nasal cavity FUNCTIONS OF THE NOSE • • • • Filters Airway Respiration Involved in speech Olfactory receptors It warms air and sneezing dislodges materials from nose PHARNYX • is the common passageway for both the respiratory and the digestive systems. • Air from the nasal cavity and air, food, and water from the mouth pass through the pharynx. • Inferiorly, the pharynx leads to the rest of the respiratory system through the opening into the larynx and to the digestive system through the esophagus. • The pharynx is divided into three regions → Nasopharynx → Oropharynx → Laryngopharynx NASOPHARYNX • Is the superior part of the pharynx. • It is located posterior to the choanae and superior to the soft palate SOFT PALATE • Which is an incomplete muscle and connective tissue partition separating the nasopharynx from the oropharynx. UVULA • Is the posterior extension of the soft palate. • The soft palate forms the floor of the nasopharynx 30 OROPHARYNX • Extends from the uvula to the epiglottis, and the oral cavity opens into the oropharynx. • Thus, food, drink, and air all pass through the oropharynx. • The oropharynx is lined with stratified squamous epithelium, which protects against abrasion. • Two sets of tonsils, the palatine tonsils and the lingual tonsil, are located near the opening between the mouth and the oropharynx PALATINE TONSILS • are located in the lateral walls near the border of the oral cavity and the oropharynx. LINGUAL TONSIL • Is located on the surface of the posterior part of the tongue. LARYNGOPHARYNX • Passes posterior to the larynx and extends from the tip of the epiglottis to the esophagus. • Food and drink pass through the laryngopharynx to the esophagus. • A small amount of air is usually swallowed with the food and drink. • Swallowing too much air can cause excess gas in the stomach and may result in belching. • The laryngopharynx is lined with stratified squamous epithelium and ciliated columnar epithelium. NASAL CAVITY AND PHARYNX LARYNX Commonly called the voicebox, is located in the anterior throat and extends from the base of the tongue to the trachea • It has three main functions: → Maintains an open airway → Protects the airway during swallowing, → Produces the voice • The larynx consists of nine cartilage structures: three singles and three paired. • The cartilages are connected to one another by muscles and ligaments THYROID CARTILAGE/ADAM’S APPLE • First single and largest cartilage • • The thyroid cartilage is attached superiorly to the hyoid bone. CRICOID CARTILAGE • Which forms the base of the larynx on which the other cartilages rest. • The thyroid and cricoid cartilages maintain an open passageway for air movement. EPIGLOTTIS • It differs from the other cartilages in that it consists of elastic cartilage rather than hyaline cartilage. • Its inferior margin is attached to the thyroid cartilage anteriorly, and the superior part of the epiglottis projects superiorly as a free flap toward the tongue. • The epiglottis protects the airway during swallowing. It prevents swallowed materials from entering the larynx by covering the glottis ANATOMY OF THE LARYNX 31 • The three pairs of cartilages are on each side of the posterior part of the larynx CUNEIFORM CARTILAGE • The top cartilage CORNICULATE CARTILAGE • Middle cartilage ARYTENOID CARTILAGE • Bottom cartilage • The arytenoid cartilages articulate with the cricoid cartilage inferiorly. • The paired cartilages form an attachment site for the vocal folds. VESTIBULAR AND VOCAL FOLDS → The larynx also houses the vocal cords. There are two sets of ligaments that extend from the posterior surface of the thyroid cartilage to the paired cartilages. VESTIBULAR FOLDS/ FALSE VOCAL CORDS → Superior set of ligaments VOCAL FOLDS/ TRUE VOCAL CORDS → Inferior set of ligaments • When the vestibular folds come together, they prevent air from leaving the lungs, as when a person holds his or her breath. • Along with the epiglottis, the vestibular folds also prevent food and liquids from entering the larynx. • The vocal folds are the primary source of voice production. Air moving past the vocal folds causes them to vibrate, producing sound. • Muscles control the length and tension of the vocal folds. • The force of air moving past the vocal folds controls the loudness, and the tension of the vocal folds controls the pitch of the voice. LARYNGITIS • An inflammation of the mucous epithelium of the vocal folds • Swelling of the vocal folds during laryngitis inhibits voice production • • TRACHEA/ WINDPIPE Allows air to flow into the lungs. It is a membranous tube attached to the larynx. It consists of connective tissue and smooth muscle, reinforced with 16–20 C-shaped pieces of hyaline cartilage • • • • • • • • • The adult trachea is about 1.4–1.6 centimeters (cm) in diameter and about 10–11 cm long. It begins immediately inferior to the cricoid cartilage, which is the most inferior cartilage of the larynx. The trachea projects through the mediastinum and divides into the right and left primary bronchi at the level of the fifth thoracic vertebra The esophagus lies immediately posterior to the trachea The trachea is lined with a mucous membrane. This membrane consists of pseudostratified columnar epithelium, containing numerous cilia and goblet cells. The cilia sweep the mucus embedded with foreign particles into the pharynx, where it is swallowed. Constant, long-term irritation of the trachea by cigarette smoke can cause the tracheal epithelium to change to stratified squamous epithelium. The stratified squamous epithelium has no cilia and therefore cannot clear the airway of mucus and debris. The accumulations of mucus provide a place for microorganisms to grow, resulting in respiratory infections. 32 • • • • • Constant irritation and inflammation of the respiratory passages stimulate the cough reflex, resulting in “smoker’s cough.” BRONCHI The trachea divides into the left and right main bronchi (windpipe), or primary bronchi, each of which connects to a lung. The left main bronchus is more horizontal than the right main bronchus because it is displaced by the heart Foreign objects that enter the trachea usually lodge in the right main bronchus, because it is wider, shorter, and more vertical than the left main bronchus and is more in direct line with the trachea. The main bronchi extend from the trachea to the lungs. Like the trachea, the main bronchi are lined with pseudostratified ciliated columnar epithelium and are supported by C-shaped pieces of cartilage. • • • • • • • LUNGS • The lungs are the principal organs of respiration. Each lung is cone-shaped, with its base resting on the diaphragm and its apex extending superiorly to a point about 2.5 cm above the clavicle. The right lung has three lobes: → superior lobe → middle lobe → inferior lobe The left lung has two lobes, called the superior lobe and the inferior lobe. The lobes of the lungs are separated by deep, prominent fissures on the lung surface. Each lobe is divided into bronchopulmonary segments separated from one another by connective tissue septa, but these separations are not visible as surface fissures. Because major blood vessels and bronchi do not cross the septa, individual diseased bronchopulmonary segments can be surgically removed, leaving the rest of the lung relatively intact. There are nine bronchopulmonary segments in the left lung and ten in the right lung BRONCHIOLES AND ALVEOLI • A terminal bronchiole branches to form respiratory bronchioles, which give rise to alveolar ducts. • Alveoli connect to the alveolar ducts and respiratory bronchioles. • The alveolar ducts end as two or three alveolar sacs. BRONCHIOLES • Bronchi continue to branch many times, finally giving rise to bronchioles 33 TERMINAL BRONCHIOLES & RESPIRATORY BRONCHIOLES • The bronchioles also subdivide numerous times to give rise to terminal bronchioles, which then subdivide into respiratory bronchioles ALVEOLAR DUCTS • long, branching ducts with many openings into alveoli. ALVEOLI • Are small air-filled chambers where the air and the blood come into close contact with each other • The alveoli become so numerous that the alveolar duct wall is little more than a succession of alveoli. ALVEOLAR SACS • Which are chambers connected to two or more alveoli. • There are about 300 million alveoli in the lungs. ALVEOLAR MACROPHAGES • Phagocytized in a particle that gets deep into the lungs type 2 or Alveolar cells antimicrobial secretion protects against foreign microbial invasion 1. 2. 3. 4. LUNG AIRWAY PASSAGES Primary Bronchi Lobar (Secondary) Bronchi Segmental (Tertiary) Bronchi Bronchioles • • • • • • • • 5. Terminal Bronchioles 6. Respiratory Bronchioles 7. Alveolar Ducts 8. Alveoli Structures become smaller and more numerous from primary bronchi to alveoli From the primary bronchi each main bronchus divides into lobar bronchi or your secondary bronchi, as they enter the respective lungs The lobar bronchi conduct air to each lung lobe and there are two lobar bronchi in the left and three for the right lung the lobar bronchi in turn divide into segmental bronchi or tertiary bronchi which lead to bronchopulmonary segments of the lungs The bronchi continue to branch many times finally giving rise to bronchioles The bronchioles also subdivide numerous times to give rise to terminal bronchus which then subdivided into respiratory bronchioles Each respiratory bronchiole subdivides to form alveolar ducts, the long branching ducts with mainly opening into alveoli The alveoli or your hollow sacs are small air filled chambers where the air and the blood come into close contact with each other • • • • • • The alveoli becomes so numerous that the alveolar ducts wall is little more than the succession of alveoli The alveolar ducts ends as two or three alveolar sacs which are chambers connected to two or more alveoli ASTHMA ATTACK Relaxation and contraction of the smooth muscle within the bronchi and bronchioles can change the diameter of the air passageways. For example, during exercise the diameter can increase, thus increasing the volume of air moved. During an asthma attack, however, contraction of the smooth muscle in the terminal bronchioles can result in greatly reduced airflow. In severe cases, air movement can be so restricted that death results. Fortunately, medications, such as albuterol, help counteract the effects of an asthma attack by promoting smooth muscle relaxation in the walls of terminal bronchioles, so that air can flow more freely. 34 ALVEOLUS AND THE RESPIRATORY MEMBRANE • • • • • • The respiratory membrane of the lungs is where gas. Exchange between the air and blood takes place. It is formed mainly by the walls of the alveoli and the surrounding capillaries. To facilitate the diffusion of gases, the respiratory membrane is very thin; it is thinner than a sheet of tissue paper. The respiratory membrane consists of two layers of simple squamous epithelium, including secreted fluids, called alveolar fluid, and separating spaces. The individual layers are the following: → A thin layer of alveolar fluid • → The alveolar epithelium, composed of a single layer of cells—simple squamous epithelium → The basement membrane of the alveolar epithelium → A thin interstitial space → The basement membrane of the capillary endothelium → The capillary endothelium, also composed of a single layer of cells— simple squamous epithelium The elastic fibers surrounding the alveoli allow them to expand during inspiration and recoil during expiration. The lungs are very elastic and, when inflated, are capable of expelling the air and returning to their original, uninflated state. Specialized secretory cells within the walls of the alveoli secrete a chemical, called surfactant, that reduces the tendency of alveoli to recoil or Lung Recoil • The parietal pleura is continuous with the visceral pleura VISCERAL PLEURA • Membrane that covers lung’s surface PLEURAL CAVITY • Space around each lung PLEURAL FLUID • The pleural cavity, between the parietal and visceral pleurae, is filled with a small volume of pleural fluid produced by the pleural membranes. • pleural fluid performs two functions: (1) It acts as a lubricant, allowing the visceral and parietal pleurae to slide past each other as the lungs and thorax change shape during respiration (2) It helps hold the pleural membranes together. PLEURAL CAVITIES AND MEMBRANES PLEURAL CAVITIES PLEURA • Double-layered serous membrane around lungs • Consists of Parietal and Visceral Pleura PARIETAL PLEURA • Membrane that lines thoracic cavity, (thorax, diaphragm, and mediastinum) • Transverse section of the thorax, showing the relationship of the pleural cavities to 35 • the thoracic organs. Each lung is surrounded by a pleural cavity. The parietal pleura lines the wall of each pleural cavity, and the visceral pleura covers the surface of the lungs. The space between the parietal and visceral pleurae is small and filled with pleural fluid. LYMPHATIC SUPPLY • The lungs have two lymphatic supplies: the superficial lymphatic vessels and the deep lymphatic vessels. SUPERFICIAL LYMPHATIC VESSELS • Are deep to the visceral pleura. • They drain lymph from the superficial lung tissue and the visceral pleura. DEEP LYMPHATIC VESSELS • Follow the bronchi. • They drain lymph from the bronchi and associated connective tissues. No lymphatic vessels are located in the walls of the alveoli. • Both the superficial and deep lymphatic vessels exit the lungs at the main bronchi. VENTILATION Ventilation (breathing) • A process of moving air in and out of the lungs • Uses the diaphragm, which is a skeletal muscle that separates the thoracic and abdominal cavities • 2 phases: Inspiration and Expiration INSPIRATION/INHALATION → Is the movement of air into the lungs EXPIRATION/ EXHALATION → Is the movement of air out of the lungs • Ventilation is regulated by changes in thoracic volume, which produce changes in air pressure within the lungs. EFFECT OF THE MUSCLES OF RESPIRATION ON THORACIC VOLUME • The muscles associated with the ribs are responsible for ventilation MUSCLES OF INSPIRATION • Inhaling requires a set of muscles called the muscles of inspiration. • The muscles of inspiration include the diaphragm and the muscles that elevate the ribs and sternum, such as the external intercostals DIAPHRAGM • is a large dome of skeletal muscle that separates the thoracic cavity from the abdominal cavity MUSCLES OF EXPIRATION • Forceful exhalation requires a set of muscles called the muscles of expiration. • The muscles of exhalation include the internal intercostals and depress the ribs and sternum → At the end of a normal, quiet expiration, the respiratory muscles are relaxed → During quiet inspiration, muscles of inspiration contract to increase the volume of the thoracic cavity. → Contraction of the diaphragm causes the top of the diaphragm to move inferiorly. → Contraction of the external intercostals also elevates the ribs and sternum to increase thoracic cavity volume. → The largest change in thoracic cavity volume is due to contraction of the diaphragm. → Expiration occurs when the thoracic cavity volume decreases. During quiet expiration, the diaphragm and external intercostals relax. → The elastic properties of the thorax and lungs cause them to recoil into a relaxed state. 36 → There are several differences between normal, quiet breathing and labored breathing. During labored breathing, there is a much greater increase in thoracic cavity volume. All the inspiratory muscles are active, and they contract more forcefully than during quiet breathing. → Also during labored breathing, the internal intercostals and the abdominal muscles contract forcefully. This decreases thoracic cavity volume more quickly and to a greater degree than during quiet breathing. • PRESSURE CHANGES AND AIRFLOW Two physical principles govern the flow of air into and out of the lungs: → Changes in volume result in changes in pressure → Air flows from an area of higher pressure to an area of lower pressure • • • • • • • • • • • • • LUNG RECOIL Is the tendency for an expanded lung to decrease in size Occurs during quiet expiration Is due to elastic fibers and thin film of fluid lining alveoli Surface tension exists because the oppositely charged ends of water molecules are attracted to each other As the water molecules pull together, they also pull on the alveolar walls, causing the alveoli to recoil and become smaller Two factors keep the lungs from collapsing: (1) surfactant and (2) pressure in the pleural cavity. SURFACTANT Lecithin and Sphingomyelin – 2:1 ratio 35 weeks gestation or 7 months old, lung surfactants is already matured A mixture of lipoproteins Is produced by secretory cells of the alveoli Is a single fluid layer on the surface of thin fluid lining alveoli Reduces surface tension Keeps lungs from collapsing FACTORS THAT INFLUENCE PULMONARY VENTILATION LUNG ELASTICITY • Lungs need to recoil between ventilations • Decreased by emphysema • Emphysema is a long-term progressive disease of the lungs that primarily causes shortness of breath due to over-inflation of the alveoli or the air sacs in the lungs LUNG COMPLIANCE • Expansion of thoracic cavity • Affected if rib cage is damaged RESPIRATORY PASSAGEWAY RESISTANCE • Occurs during an asthma attack, infection, tumor PULMONARY VOLUMES SPIROMETRY • Is the process of measuring volumes of air that move into and out of the respiratory system SPIROMETER • Device that measures pulmonary volumes • Measurements of the respiratory volumes can provide information about the health of the lungs 37 TIDAL VOLUME (TV) • Volume of air inspired and expired during quiet breathing RESPIRATORY VOLUMES & RESPIRATORY CAPACITIES • • INSPIRATORY RESERVE VOLUME (IRV) • Volume of air that can be inspired forcefully after a normal inspiration EXPIRATORY RESERVE VOLUME (ERV) • Volume of air that can be expired forcefully after a normal expiration RESIDUAL VOLUME (RV) • Volume of air remaining in lungs after a maximal expiration (can’t be measured with spirometer) → The tidal volume increases during physical activity. The increase in the tidal volume reduces the inspiratory and expiratory reserve volumes, but total lung capacity stays relatively constant. VITAL CAPACITY (VC) • Max. amount of air a person can expire after a max. inspiration ππΆ = πΌπ π + πΈπ π + ππ • Total lung capacity (TLC) ππΏπΆ = ππΆ + π π O2 diffuses from alveoli into pulmonary capillaries (blood) CO2 diffuses from capillaries into alveoli GAS EXCHANGE • • • The tidal volume shown here is during resting conditions. Respiratory volumes are measurements of the volume of air moved into and out of the lungs during breathing. Respiratory capacities are the sum of two or more respiratory volumes. FACTORS THAT INFLUENCE THE PULMONARY VOLUMES → Gender → Age → Height → Weight of the client • • DIFFUSION OF GASES IN LUNGS Cells in body use O2 and produce CO2. Blood returning from tissues and entering lungs has a decreased Po2 and increased Pco2 • Differences in partial pressure are responsible for the exchange of O2 and CO2 that occurs between the alveoli and the pulmonary capillaries and between the tissues and the tissue capillaries 38 GAS EXCHANGE IN THE TISSUES H2CO3. Oxygen diffuses into red blood cells and binds to hemoglobin. • • • In the tissues, CO2 diffuses into red blood cells, where the enzyme carbonic anhydrase (CA) is located CA catalyzes the reaction of CO2 with H2O to form carbonic acid (H2CO3). H2CO3 dissociates to form bicarbonate ions (HCO3–) and hydrogen ions (H+). Oxygen is released from hemoglobin (Hb) and diffuses into tissue cells. • • • GAS EXCHANGE IN THE LUNGS • • • In the lungs, CO2 diffuses from red blood cells into the alveoli. CA catalyzes the formation of CO2 and H2O from H2CO3. H+ and HCO3 – combine to replace the respiratory system regulates oxygen and carbon dioxide levels within the blood respiration includes ventilation, gas exchange between the air, blood and tissues within the body and the use of oxygen for metabolism inhalation allows oxygen to enter the body pulling air into the nose and mouth, lungs and into the air sacs called alveoli where gas exchange takes place alveoli move freely when air is inhaled and exhaled, capillaries are small blood vessels that line the walls of the alveoli During gas exchange, oxygen enters and carbon dioxide exits the bloodstream via the alveolocapillary membrane, once oxygen molecules move from the alveoli into the capillaries, they dissolve into the plasma and enter the red blood cell or erythrocyte Erythrocytes contain millions of soluble proteins called hemoglobin Hemoglobin contains four subunits each capable of binding one molecule of oxygen once one molecule of oxygen binds to one of the subunits the other sites bind oxygen more readily • • • • • • • Dissolved and bound oxygen flows through the arterial bloodstream to capillaries within tissues, upon arrival carbon dioxide loading of the erythrocyte promotes oxygen unloading Oxygen metabolism within cells produces carbon dioxide gas as a metabolic waste, carbon dioxide exits the cells and tissues and is converted into bicarbonate within the erythrocytes converting carbon dioxide to bicarbonate releases hydrogen ions that decrease oxygen affinity for hemoglobin freeing the oxygen to be delivered to tissue cells After delivering oxygen to the tissues, the carbon dioxide rich blood returns to the lungs through the venous circulation and then to the pulmonary artery inside each erythrocyte The bicarbonate conversion is reversed recreating carbon dioxide which diffuses across the erythrocyte into the alveoli and lungs and is excreted out of the body RHYTHMIC VENTILATION Normal respiratory rate is 12 to 20 respirations per minute (adults). In children, the rates are higher and may vary from 20 to 40 per minute. The rhythm is controlled by neurons in the medulla oblongata. 39 • Rate is determined by the number of times respiratory muscles are stimulated. NERVOUS AND CHEMICAL MECHANISMS OF BREATHING RESPIRATORY STRUCTURES IN THE BRAINSTEM • • • Internal respiration is the exchange of gases with the internal environment, and occurs in the tissues. External respiration, also known as breathing, involves both bringing air into the lungs (inhalation) and releasing air to the atmosphere (exhalation). Several regulatory mechanisms affect the rate and depth of breathing. A plus sign indicates that the mechanism increases breathing and a minus sign indicates that it results in a decrease in breathing NERVOUS CONTROL OF BREATHING Higher brain centers allow voluntary breathing • Emotions and speech affect breathing HERING-BREUER REFLEX • Inhibits respiratory center when lungs are stretched during inspiration • • Specific structures in the brainstem correlate with the nerves that innervate the muscles of respiration. (1) Blood pH is in its normal range. (2) Blood pH increases outside its normal range, which disturbs homeostasis. (3) The control centers for blood pH, the medullary chemoreceptors, detect an increase in blood pH (blood becomes more 40 basic) and respond to the increased pH by signaling a decreased breathing rate. (4) The effectors, the diaphragm and other respiratory muscles, respond by slowing their contraction rate, which lowers the rate of breathing. (5) As a result, more CO2 is retained, which causes pH to drop (blood becomes more acidic). (6) Blood pH returns to its normal range and homeostasis is maintained. • • • • CHEMICAL CONTROL OF BREATHING Chemoreceptors in medulla oblongata respond to changes in blood pH Blood pH are produced by changes in blood CO2 levels An increase in CO2 causes decreased pH, result is increased breathing Low blood levels of O2 stimulate chemoreceptors in carotid and aortic bodies, increased breathing DEFINITIONS INTERNAL RESPIRATION • Exchange of gases between the cells and the blood EXTERNAL RESPIRATION • Occurs in the lungs exchange of gases between blood and the alveoli APNEA • There is a temporary cessation of breathing DYSPNEA • The difficulty or labor breathing HYPERVENTILATION • Breathe very fast exhaling more than inhaling decreasing the carbon dioxide HYPOVENTILATION • Also known as the respiratory depression • There is an increase of carbon dioxide causing acidosis COPD • Chronic obstructive pulmonary disease REPRESENTATIVE DISEASES AND DISORDERS: RESPIRATORY SYSTEM EFFECT OF ASTHMA • Strenuous exercise is one of the many factors that can bring on an asthma attack. • Asthma is a chronic inflammatory disease that obstructs air flow in and out of the bronchial tubes Normally as the diaphragm contracts and relaxes air moves freely in and out of the trachea and bronchi to the bronchioles and then to the alveoli where gas exchange takes place During this process carbon dioxide will diffuse out of the bloodstream into the • • 41 • • • alveolus while oxygen will diffuse from the alveolus into the bloodstream Smooth muscle in the bronchial walls is controlled by the autonomic nervous system sympathetic stimulation relaxes smooth muscle and produces bronchodilation when the air is warm, moist and free of irritants parasympathetic stimulation contracts smooth muscle and produces bronchoconstriction when the air is cold dry or contains irritants INFLAMMATION • People with asthma have chronically inflamed and swollen airways that are hyper reactive to irritants that can trigger an asthma attack Asthma triggers include • Outdoor irritants and allergens → Pollen, smoke, pollution and cold weather • Indoor irritants and allergens → Mold, pet dander, dust mites, and cockroach droppings • Food allergens → Fish, shellfish, eggs, peanuts and soy • Physiological conditions → Respiratory infections, stress and strong emotions and exercise • • • BRONCHOSPASM During an asthma attack these triggers can induce mast cells and leukocytes to release chemical substances such as histamine, kinins prostaglandins and leukotrienes, these substances are chemical mediators of inflammation that can precipitate a bronchospasm Suddenly the bronchial smooth muscle tightens and the bronchial wall becomes more swollen, goblet cells in the mucosa produce thicker mucous further obstructing the airway this combination of factors slows normal gas exchange BRONCHOSPASM SYMPTOMS Coughing, wheezing, shortness of breath and chest tightness MEDICINES THAT TREAT ASTHMA Long-acting anti-inflammatory drugs • Corticosteroids, leukotriene inhibitors and cromolyn sodium → These drugs keep asthma under control by preventing or reducing inflammation of the bronchial wall this makes the airways less sensitive to bronchospasm triggers, regular use of maintenance medications makes it less likely that an asthma flare-up will take place Bronchodilator drugs • Beta-agonists (short-acting) • • • • Theophylline (long-acting) Anticholinergics → These drugs cause the bronchial smooth muscle to relax quickly or gradually over a longer period of time → Regular use of long-acting maintenance medications is critical in keeping your airways open and less inflamed, this reduces the likelihood of asthma flareups SHORT-ACTING RESCUE MEDICATION Occasional, as-needed use during flare-ups (bronchospasm) When flare-ups do happen it is important for patients to work with their licensed health care professional to develop an action plan for the correct use of short acting rescue medication rescue medication opens airways quickly providing symptom relief within minutes 42 MUSCULAR SYSTEM TYPES OF MUSCLES SKELETAL • Attached to the bones • Striated • Voluntary CARDIAC • Located in the Heart • Striated • Involuntary SMOOTH • Blood vessels and Hollow organs • Nonstriated • Involuntary FUNCTIONS OF THE MUSCULAR SYSTEM 1. Movement of the body → Contraction of skeletal muscles is responsible for the overall movements of the body, such as walking, running, and manipulating objects with the hands. 2. Maintenance of posture → Skeletal muscles constantly maintain tone, which keeps us sitting or standing erect. 3. Respiration → Muscles of the thorax carry out breathing movements. 4. Production of body heat → When skeletal muscles contract, heat is given off as a by-product. This released heat is critical to the maintenance of body temperature. 5. Communication → Skeletal muscles are involved in all aspects of communication, including speaking, writing, typing, gesturing, and facial expressions. 6. Constriction of organs and vessels → The contraction of smooth muscle within the walls of internal organs and vessels causes those structures to constrict. This constriction can help propel and mix food and water in the digestive tract, propel secretions from organs, and regulate blood flow through vessels. 7. Contraction of the heart → The contraction of cardiac muscle causes the heart to beat, propelling blood to all parts of the body. PROPERTIES OF MUSCLES CONTRACTILITY • is the ability of muscle to shorten forcefully, or contract. EXCITABILITY • is the capacity of muscle to respond to a stimulus EXTENSIBILITY • means that a muscle can be stretched beyond its normal resting length and still be able to contract. ELASTICITY • is the ability of muscle to recoil to its original resting length after it has been stretched. • • • • • THE MUSCULAR SYSTEM Skeletal muscle, or striated muscle, with its associated connective tissue, constitutes approximately 40% of body weight. Skeletal muscle is so named because many of the muscles are attached to the skeletal system. Some skeletal muscle attaches to the skin or connective tissue sheets. Skeletal muscle is also called striated muscle because transverse bands, or striations, can be seen in the muscle under the microscope. Individual skeletal muscles, such as the biceps brachii, are complete organs, as a result of being comprised of several tissues, muscles, nerves and connective tissue 43 CONNECTIVE TISSUE COVERINGS EPIMYSIUM • Muscular fascia • Each skeletal muscle (such as the biceps brachii) is surrounded by a connective tissue sheath called the epimysium FASCICLES • A Skeletal muscle is subdivided into groups of muscle cells called fascicles PERIMYSIUM • Each fascicle is surrounded by connective tissue covering ENDOMYSIUM • Each skeletal muscle fiber is surrounded by a connective tissue covering called endomysium • • MUSCLE FIBER STRUCTURE A single cylindrical cell with several nuclei located at its periphery The muscle fiber range 1 cm to 30 cm and are generally 0.15 millimeter diameter SARCOLEMMA • cell membrane of the muscle fiber • has many tubelike inward folds, called transverse tubules, or T tubules. T TUBULES • occur at regular intervals along the muscle fiber and extend into the center of the muscle fiber. • The T tubules are associated with enlarged portions of the smooth endoplasmic reticulum called the sarcoplasmic reticulum • The enlarged portions are called terminal cisternae. • T tubules connect the sarcolemma to the terminal cisternae to form a triad • The sarcoplasmic reticulum has a relatively high concentration of Ca2+, which plays a major role in muscle contraction. SARCOPLASM • The cytoplasm of a muscle fiber • Contains many bundles of protein filaments. MYOFIBRILS • These bundles are called myofibrils • Myofibrils consist of two major kinds of protein fibers: actin myofilaments and myosin myofilaments STRUCTURES OF A MUSCLE SARCOMERE ACTIN MYOFILAMENT (THIN FILAMENT) • Is one of protein fibers that make up a sarcomere • Resembles two-minute strands of pearls MYOSIN MYOFILAMENT (THICK FILAMENT) • Is another protein fibers that make up a sarcomere • It resembles a tiny golf clubs MYOFIBRIL • It is a longitudinal fibril within a skeletal muscle fiber I BAND • Is a region of a striated muscle sarcomere that contains the thin filaments A BAND • A region of striated muscle sarcomere that contains myosin thick filaments 44 H ZONE • Is a center of A Band where there is no overlap between the thick and thin myofilaments M LINE • Is the attachment site for the thick myofilaments • It is the center of A Band and Sarcomere Z DISK • The boundaries of a muscle sarcomere • Two adjacent Z disks along the myofibril mark the boundaries of a single sarcomere TROPONIN • A complex of three regulatory proteins that are integral to muscular contraction in skeletal and cardiac muscle but not on the smooth muscle TROPOMYOSIN • A two-stranded alpha-helical coiled coil protein found in the cell cytoskeletons • SKELETAL MUSCLE FIBER SARCOMERE • The sarcomere is the basic structural and functional unit of a skeletal muscle because it is the smallest portion of a skeletal muscle capable of contracting Z DISK • is a network of protein fibers that forms a stationary anchor for actin myofilaments to attach. ACTIN AND MYOSIN MYOFILAMENTS • Actin myofilaments, or thin filaments, are made up of three components: actin, troponin, and tropomyosin. TROPONIN MOLECULES • Have binding sites for Ca2+. TROPOMYOSIN FILAMENTS • Block the myosin myofilament binding sites on the actin myofilaments. One sarcomere extends from one Z disk to the next Z disk → The organization of actin and myosin myofilaments in a gives skeletal muscle its striated appearance and the ability to contract → The myofilaments slide past each other, causing the sarcomeres to shorten. I BAND • Each sarcomere consists of two lightstaining bands separated by a darkstaining band • Consist of only actin myofilaments • Extends toward the center of the sarcomere to the ends of the myosin myofilaments A BAND • Central dark-staining band • Actin and myosin myofilaments overlap for some distance on both ends of the A band, this causes contraction MYOSIN HEADS • Parts of the myosin molecule that resemble golf club heads → The heads bind to attachment sites on the actin myofilaments → They bend and straighten during contraction → They break down ATP, releasing energy • • • • EXCITABILITY OF MUSCLE FIBERS The electrical charge difference across the cell membrane of an unstimulated cell is called the resting membrane potential. Muscle Cells/Fibers have a resting membrane potential but can also perform action potentials The resting membrane potential is due to the inside of the membrane being negatively charged in comparison to the outside of the membrane being positively charged The action potentials are due to the membrane having a gated channels 45 RESTING MEMBRANE POTENTIAL • • • • • • To initiate a muscle contraction, the resting membrane potential must be changed to an action potential Changes in the resting membrane potential occurs when gated cell membrane channels open It the skeletal muscle fiber, a nerve impulse triggers gated Na+ channels to open, and Na+ diffuses into the cell down its concentration gradient and toward the negative charges into the cell REPOLARIZATION • • DEPOLARIZATION • • • Depolarization during the action potential is when the inside of the cell membrane becomes more positively charged than the outside of the cell membrane The entry of Na+ causes the inside of the cell membrane to become more positive Increases positive charge in the cell membrane If the depolarization changes the membrane potential to a value called threshold, an action potential is triggered. An action potential is a rapid change in charge across the cell membrane. • Near the end of depolarization, the positive charge causes gated Na+ channels to close and gated K+ channels to open Opening of gated K+ channels starts repolarization of the cell membrane Repolarization is due to the exit of K+ from the cell. The outward diffusion of K+ returns the cell to its resting membrane conditions and the action potential ends. In a muscle fiber, an action potential results in muscle contraction. NERVE SUPPLY AND MUSCLE FIBER STIMULATION MOTOR NEURONS • Are specialized nerve cells that stimulate muscles to contract NEUROMUSCULAR JUNCTION • Is a synapse, where the fiber of a nerve connects to a muscle fiber • Each branch forms a junction with a muscle fiber SYNAPSE • The cell-to-cell junction between a nerve cell and either another nerve cell or an effector cell, such as in a muscle or a gland. MOTOR UNIT • A group of muscle fibers that a moto neuron stimulates PRESYNAPTIC TERMINAL • Is the end neuron cell axon fiber SYNAPTIC CLEFT • Is the space between the presynaptic terminal and post synaptic membrane 46 POST SYNAPTIC MEMBRANE • The muscle fiber membrane or the sarcolemma SYNAPTIC VESICLES • A vesicle in the presynaptic terminal that stores and releases neurotransmitter chemicals NEUROTRANSMITTER • Are chemicals that stimulates or inhibit the post synaptic cells ACETYLCHOLINE OR ACH • A neurotransmitter that stimulates skeletal muscles • • • Acetylcholine, from the Synaptic Vesicles into the synaptic cleft Diffusion of ACh across the synaptic cleft and binding of ACh to ACh receptors on the postsynaptic muscle fiber membrane opens Na+ channels. Sodium ions diffuse their concentration gradient which result in depolarization of a muscle fiber membrane If threshold has been reached, a post synaptic action potential is achieved SKELETAL MUSCLE EXCITATION FUNCTION OF THE NEUROMUSCULAR JUNCTION • • At the presynaptic terminal, the action potential causes Ca2+ channels to open Ca2+ enters the presynaptic terminal and initiate the release of a neurotransmitter, 1. An action potential travels along an axon membrane to a neuromuscular junction. 2. Ca2+ channels open and Ca2+ enters the presynaptic terminal. 3. Acetylcholine is released from presynaptic vesicles. 4. Acetylcholine stimulates Na+ channels on the postsynaptic membrane to open. 5. Na+ diffuses into the muscle fiber, initiating an action potential that travels along the sarcolemma and T tubule membranes. 6. Action potentials in the T tubules cause the sarcoplasmic reticulum to release Ca2+. 7. On the actin, Ca2+ binds to troponin, which moves tropomyosin and exposes myosin attachment sites. 8. ATP molecules are broken down to ADP and P, which releases energy needed to move the myosin heads. 9. The heads of the myosin myofilaments bend, causing the actin to slide past the myosin. As long as Ca2+ is present, the cycle repeats. BREAKDOWN OF ATP AND CROSS-BRIDGE MOVEMENT DURING MUSCLE CONTRACTION • Energy for muscle contraction is supplied by ATP • Energy is released as ATP breaks • Down to adenosine diphosphate (ADP) and phosphate (P). • The energy released from ATP is briefly stored in the myosin head. • An ATP help from cross-bridge formation between myosin and actin • New ATP must bind to myosin before crossbridge is released 47 molecules are released from the myosin heads. 4. Cross-bridge release. An ATP molecule binds to each of the myosin heads, causing them to detach from the actin. 5. Hydrolysis of ATP. The myosin ATPase portion of the myosin heads split ATP into ADP and phosphate (P), which remain attached to the myosin heads. 6. Recovery stroke. The heads of the myosin molecules return to their resting position, and energy is stored in the heads of the myosin molecules. If Ca2+ is still attached to troponin, cross-bridge formation and movement are repeated. This cycle occurs many times during a muscle contraction. Not all cross-bridges form and release simultaneously. 1. Exposure of active sites. Before crossbridge cycle, calcium binds to the troponin, and tropomyosin moves exposing active sites on actin myofilaments 2. Cross-bridge formation. The myosin heads bind to the exposed active sites on the actin myofilaments to form cross-bridges, and phosphates are released from the myosin heads. 3. Power stroke. Energy stored in the myosin heads is used to move the myosin heads, causing the actin myofilaments to slide past the myosin myofilaments, and ADP ENERGY FOR MUSCLE CONTRACTIONS • Muscle fibers are very energy demanding cells whether at rest or during any form of exercise • Energy comes from either aerobic (with oxygen) or anaerobic (without oxygen) ATP production • ATP is derived from four processes in skeletal muscle 1. Aerobic production is found in the cytoplasm and mitochondria, through Krebs Cycle or Oxidative phosphorylation and Glycolysis that produces at least 36 ATP (during most exercise and normal conditions). 2. Anaerobic production it comes from the cytoplasm through glycolysis and fermentation that produces only 2 ATP (during intensive short-term work) 3. Conversion of a molecule called creatine phosphate to ATP – function is in the muscle cells by storing energy that will be transferred to ADP to resynthesize ADP 4. Conversion of two ADP to one ATP and one AMP (adenosine monophosphate) (during heavy exercise) • MUSCLE TWITCH A muscle twitch is a single contraction of a muscle fiber in response to a stimulus. LAG PHASE OR LATENT PHASE • Is the time between the application of a stimulus and the beginning of contraction. CONTRACTION PHASE • Is the time during which the muscle contracts 48 RELAXATION PHASE • Is the time during which the muscle relaxes. • • SKELETAL MUSCLE FIBER TYPES SLOW TWITCH FIBERS • Contract slowly • Fatigue slowly • Have a considerable amount of myoglobulin • Uses Aerobic Respiration • The color of the muscle fiber is darker • It is used by a long-distance runner FAST TWITCH FIBERS • Contract quickly • Fatigue quickly • Uses Anaerobic Respiration • Energy is from glycogen • It is lighter in color • It is used for by sprinters → A muscle has a blend of type, with one type dominating → Humans has both types of fibers → The distribution of fibers are genetically determined • MUSCLE FATIGUE Fatigue is a temporary state of reduced work capacity. Without fatigue, muscle fibers would be worked to the point of structural damage to them and their supportive tissues. Mechanisms of fatigue include: → Acidosis and ATP depletion due to either an increased ATP consumption or a decreased ATP production → Oxidative stress, which is characterized by the buildup of excess reactive oxygen species (ROS; free radicals) → Local inflammatory reactions LABORATORY SKELETAL MUSCLES TYPES OF MUSCLE CONTRACTIONS • There are two types of muscle contractions: isometric and isotonic. ISOMETRIC (EQUAL DISTANCE) CONTRACTIONS • increase the tension in the muscle without changing its length. ISOTONIC (EQUAL TENSION) CONTRACTIONS • have a constant amount of tension while decreasing the length of the muscle. CONCENTRIC CONTRACTIONS • are isotonic contractions in which muscle tension increases as the muscle shortens. ECCENTRIC CONTRACTIONS • are isotonic contractions in which tension is maintained in a muscle, but the opposing resistance causes the muscle to lengthen. 49 SKELETAL MUSCLE ANATOMY TENDON • Connects skeletal muscle to bone. APONEUROSES • Are broad, sheetlike tendons. RETINACULUM • Is a band of connective tissue ORIGIN • Skeletal muscle attachments have an origin and an insertion, with the origin being the attachment at the least mobile location. • Located in a much proximate (proximal) location, near the center of the body INSERTION • Is the end of the muscle attached to the bone undergoing the greatest movement. • Distal part BELLY • The part of the muscle between the origin and the insertion ACTION • The specific body movement a muscle contraction causes AGONISTS • A group of muscles working together ANTAGONISTS • A muscle or group of muscles that oppose muscle actions SYNERGIST • A group of muscles working together to produce a movement. PRIME MOVER • Plays a major role in accomplishing the desired movement FIXATORS • Are muscles that hold one bone in place relative to the body while a usually more distal bone is moved. • Example: Scapula, while the upper extremities are moving, the scapula has a lot of fixators that fix the location of the scapula to prevent from any dislocation or damage MUSCLE ATTACHMENT Example: Bicep Brachii • The Bicep Brachii is attached to a supraglenoid tubercle of the scapula • • (origin), its insertion is in the radial tuberosity Function: it flexes the elbow, supinates the forearm, flexes the shoulder NOMENCLATURE Muscles are named according to: 1. LOCATION → A pectoralis (chest) muscle is located in the chest → a gluteus (buttock) muscle is in the buttock → brachial (arm) muscle is in the arm. 2. SIZE → The gluteus maximus (large) is the largest muscle of the buttock → Gluteus minimus (small) is the smallest. → Longus (long) muscle is longer → Brevis (short) muscle 3. SHAPE → Deltoid (triangular) muscle is triangular in shape → Quadratus (quadrate) muscle is rectangular → Teres (round) muscle is round 4. ORIENTATION OF FASCICLES → Rectus (straight, parallel) muscle has muscle fascicles running in the same direction as the structure with which the muscle is associated 50 → Oblique muscle lie at an angle to the length of the structure. 5. ORIGIN AND INSERTION → Sternocleidomastoid has its origin on the sternum and clavicle and its insertion on the mastoid process of the temporal bone. → Brachioradialis originates in the arm (brachium) and inserts onto the radius. 6. NUMBER OF HEADS → Biceps muscle has two heads (origins) → Triceps muscle has three heads (origins). 7. FUNCTION → Abductors and adductors are the muscles that cause that type of movement. → Abduction moves a structure away from the midline → Adduction moves a structure toward the midline. MUSCLES OF MASTICATION TEMPORALIS • Origin: Temporal Fossa • Insertion: Anterior portion of the Mandibular Ramus and Coronoid Process • Action: Elevates and draws mandible posteriorly; closes jaw MASSETER • Origin: Zygomatic arch • Insertion: Lateral side of mandibular ramus • Action: Elevates and pushes mandible anteriorly; closes jaw LATERAL PTERYGOID • Origin: Lateral pterygoid plate and greater wing of sphenoid • Insertion: Condylar process of mandible and articular disk • Action: Pushes mandible anteriorly and depresses mandible; closes jaw MEDIAL PTERYGOID • Origin: Lateral pterygoid plate of sphenoid and tuberosity of maxilla • Insertion: Medial surface of mandible • Action: Pushes mandible anteriorly and elevates mandible; closes jaw MUSCLES OF FACIAL EXPRESSION BUCCINATOR • Origin: Maxilla and mandible • Insertion: Orbicularis oris at corner of mouth • Action: Draws corner of mouth posteriorly; compresses cheek to hold food between teeth DEPRESSOR ANGULI ORIS • Origin: Lower border of mandible • Insertion: Skin of lip near corner of mouth • Action: Lowers corner of mouth; “frown” LEVATOR LABII SUPERIORIS • Origin: Maxilla • Insertion: Skin and orbicularis oris of upper lip • Action: Raises upper lip; sneer 51 OCCIPITOFRONTALIS • Origin: Occipital bone • Insertion: Skin of eyebrow and nose • Action: Moves scalp; raises eyebrows ORBICULARIS OCULI • Origin: Maxilla and frontal bones • Insertion: Circles orbit and inserts onto SKIN around eyelids • Action: Closes eyes; blinking, winking, squinting ORBICULARIS ORIS • Origin: Nasal septum, maxilla, and mandible • Insertion: Fascia and other muscles of lips • Action: Closes and purses lips; “kissing” ZYGOMATICUS MAJOR • Origin: Zygomatic bone • Insertion: Angle of mouth • Action: Elevates and abducts upper lip and corner of mouth; “smile” ZYGOMATICUS MINOR • Origin: Zygomatic bone • Insertion: Orbicularis oris of upper lip • Action: Elevates and abducts upper lip; “smile” MUSCLES OF THE NECK • Action: Extends and laterally flexes neck TONGUE AND SWALLOWING MUSCLES DEEP NECK MUSCLES • Flexors and Extensors FLEXORS • Origin: Anterior side of vertebrae • Insertion: Base of skull • Action: Flex head and neck EXTENSORS • Origin: Posterior side of vertebrae • Insertion: Base of skull • Action: Extend head and neck STERNOCLEIDOMASTOID • Origin: Manubrium of sternum and medial part of clavicle • Insertion: Mastoid process and nuchal line of skull • Action: Individually rotate head; together flex neck TRAPEZIUS • Origin: Posterior surface of skull and upper vertebral column (C7–T12) • Insertion: Clavicle, acromion process, and scapular spine TONGUE MUSCLES • Intrinsic and Extrinsic INTRINSIC • Origin: Inside tongue • Insertion: Inside tongue • Action: Changes shape of tongue EXTRINSIC • Origin: Bones around oral cavity or soft palate • Insertion: Onto tongue • Action: Moves tongue HYOID MUSCLES • Suprahyoid (Geniohyoid, stylohyoid, and hyoglossus) and Infrahyoid SUPRAHYOID • Origin: Base of skull, mandible • Insertion: Hyoid bone • Action: Elevates or stabilizes hyoid 52 INFRAHYOID • Origin: Sternum, larynx • Insertion: Hyoid bone • Action: Depresses or stabilizes hyoid PHARYNGEAL MUSCLES • Elevators, Constrictors, Superior, Middle, Inferior ELEVATORS • Origin: Soft palate and auditory tube • Insertion: Pharynx • Action: Elevate pharynx CONSTRICTORS • Origin: Larynx and hyoid • Insertion: Pharynx • Action: Constrict pharynx SUPERFICIAL • Erector spinae divides into three columns: Iliocostalis, Longissimus, Spinalis • Origin: Sacrum, ilium, vertebrae, and ribs • Insertion: Ribs, vertebrae, and skull • Action: Extends vertebral column; maintains posture DEEP BACK MUSCLES • Origin: Vertebrae • Insertion: Vertebrae • Action: Extend vertebral column and help bend vertebral column laterally • Action: Inspiration; elevate ribs for inspiration INTERNAL INTERCOSTALS • Origin: Superior edge of each rib • Insertion: Inferior edge of next rib above origin • Action: Forced expiration; depress ribs DIAPHRAGM • Origin: Inferior ribs, sternum, and lumbar vertebrae • Insertion: Central tendon of diaphragm • Action: Inspiration; depress floor of thorax; moves during quiet breathing THORACIC MUSCLES ABDOMINAL WALL MUSCLES BACK MUSCLES SCALENES • Origin: Cervical vertebrae • Insertion: First and second ribs • Action: Inspiration; elevate ribs EXTERNAL INTERCOSTALS • Origin: Inferior edge of each rib • Insertion: Superior edge of next rib below origin RECTUS ABDOMINIS • Origin: Pubic crest and pubic symphysis • Insertion: Xiphoid process and inferior ribs • Action: Flexes vertebral column; compresses abdomen EXTERNAL ABDOMINAL OBLIQUE • Origin: Ribs 5–12 53 • Insertion: Iliac crest, inguinal ligament, and fascia of rectus abdominis • Action: Compresses abdomen; flexes and rotates vertebral column INTERNAL ABDOMINAL OBLIQUE • Origin: Iliac crest, inguinal ligament, and lumbar fascia • Insertion: Ribs 10–12 and fascia of rectus abdominis • Action: Compresses abdomen; flexes and rotates vertebral column TRANSVERSUS ABDOMINIS • Origin: Costal cartilages 7–12, lumbar fascia, iliac crest, and inguinal ligament • Insertion: Xiphoid process, fascia of rectus abdominis, and pubic tubercle • Action: Compresses abdomen UPPER SCAPULAR AND LIMB MUSCLES LEVATOR SCAPULAE • Origin: Transverse processes of C1–C4 • Insertion: Superior angle of scapula • Action: Elevates, retracts, and rotates scapula; laterally flexes neck PECTORALIS MINOR • Origin: Ribs 3–5 • Insertion: Coracoid process of scapula • Action: Depresses scapula or elevates ribs RHOMBOIDS MAJOR • Origin: Spinous processes of T1–T4 • Insertion: Medial border of scapula • Action: Retracts, rotates, and fixes scapula RHOMBOIDS MINOR • Origin: Spinous processes of T1–T4 • Insertion: Medial border of scapula • Action: Retracts, slightly elevates, rotates, and fixes scapula SERRATUS ANTERIOR • Origin: Ribs 1–9 • Insertion: Medial border of scapula • Action: Rotates and protracts scapula; elevates ribs TRAPEZIUS • Origin: Posterior surface of skull and spinous processes of C7–T12 • Insertion: Clavicle, acromion process, and scapular spine • Action: Elevates, depresses, retracts, rotates, and fixes scapula; extends neck UPPER LIMB MUSCLES DELTOID • Origin: Clavicle, acromion process, and scapular spine of scapula • Insertion: Deltoid tuberosity of humerus • Action: Flexes and extends shoulder; abducts and medially and laterally rotates arm LATISSIMUS DORSI • Origin: Spinous processes of T7–L5, sacrum and iliac crest, and inferior angle of scapula in some people • Insertion: Medial crest of intertubercular groove of humerus • Action: Extends shoulder; adducts and medially rotates arm PECTORALIS MAJOR • Origin: Clavicle, sternum, superior six costal cartilages, and abdominal muscles 54 • • Insertion: Lateral crest of intertubercular groove of humerus Action: Flexes shoulder; extends shoulder from flexed position; adducts and medially rotates arm ROTATOR CUFF INFRASPINATUS • Origin: Infraspinous fossa of scapula • Insertion: Greater tubercle of humerus • Action: Stabilizes and extends shoulder and laterally rotates arm SUBSCAPULARIS • Origin: Subscapular fossa of scapula • Insertion: Lesser tubercle of humerus • Action: Stabilizes and extends shoulder and medially rotates arm SUPRASPINATUS • Origin: Supraspinous fossa of scapula • Insertion: Greater tubercle of humerus • Action: Stabilizes shoulder and abducts arm TERES MINOR • Origin: Lateral border of scapula • Insertion: Greater tubercle of humerus • Action: Stabilizes and extends shoulder; adducts and laterally rotates arm BICEPS BRACHII • Origin: → Long head—supraglenoid tubercle of scapula → Short head—coracoid process of scapula • Insertion: Radial tuberosity and aponeurosis of biceps brachii • Action: Flexes elbow; supinates forearm; flexes shoulder BRACHIALIS • Origin: Anterior surface of humerus • Insertion: Coronoid process of ulna • Action: Flexes elbow TRICEPS BRACHII • Origin: → Long head—lateral border of scapula → Lateral head—lateral and posterior surface of humerus → Medial head—posterior humerus • Insertion: Olecranon process of ulna • Action: Extends elbow; extends shoulder; adducts arm MUSCLES OF THE FOREARM ANTERIOR FOREARM PALMARIS LONGUS • Origin: Medial epicondyle of humerus • Insertion: Aponeurosis over palm • Action: Tightens skin of palm FLEXOR CARPI RADIALIS • Origin: Medial epicondyle of humerus • Insertion: Second and third metacarpal bones • Action: Flexes and abducts wrist FLEXOR CARPI ULNARIS • Origin: Medial epicondyle of humerus and ulna • Insertion: Pisiform • Action: Flexes and adducts wrist FLEXOR DIGITORUM PROFUNDUS • Origin: Ulna • Insertion: Distal phalanges of digits 2–5 • Action: Flexes fingers and wrist FLEXOR DIGITORUM SUPERFICIALIS • Origin: Medial epicondyle of humerus, coronoid process, and radius • Insertion: Middle phalanges of digits 2–5 • Action: Flexes fingers and wrist PRONATOR QUADRATUS • Origin: Distal ulna • Insertion: Distal radius • Action: Pronates forearm TERES • Origin: Medial epicondyle of humerus and coronoid process of ulna • Insertion: Radius • Action: Pronates forearm POSTERIOR FOREARM BRACHIORADIALIS • Origin: Lateral supracondylar ridge of humerus • Insertion: Styloid process of radius • Action: Flexes elbow 55 EXTENSOR CARPI RADIALIS BREVIS • Origin: Lateral epicondyle of humerus • Insertion: Base of third metacarpal bone • Action: Extends and abducts wrist EXTENSOR CARPI RADIALIS LONGUS • Origin: Lateral supracondylar ridge of humerus • Insertion: Base of second metacarpal bone • Action: Extends and abducts wrist EXTENSOR CARPI ULNARIS • Origin: Lateral epicondyle of humerus and ulna • Insertion: Base of fifth metacarpal bone • Action: Extends and adducts wrist EXTENSOR DIGITORUM • Origin: Lateral epicondyle of humerus • Insertion: Extensor tendon expansion over phalanges of digits 2–5 • Action: Extends fingers and wrist SUPINATOR • Origin: Lateral epicondyle of humerus and ulna • Insertion: Radius • Action: Supinates forearm (and hand) PELVIC FLOOR MUSCLES PELVIC FLOOR LEVATOR ANI • Origin: Posterior pubis and ischial spine viscera • Insertion: Sacrum and coccyx • Action: Elevates anus; supports pelvic PERINEUM BULBOSPONGIOSUS • Origin: → Male—central tendon of perineum → Female—central tendon of perineum • Insertion: → Male—Dorsal surface of penis and bulb of penis → Female—Base of clitoris • Action: → Male—Constricts urethra; erects penis → Female—Erects clitoris ISCHIOCAVERNOSUS • Origin: Ischial ramus • Insertion: Corpus cavernosum • Action: Compresses base of penis or clitoris EXTERNAL ANAL SPHINCTER • Origin: Coccyx • Insertion: Central tendon of perineum • Action: Keeps orifice of anal canal closed TRANSVERSE PERINEI DEEP • Origin: Ischial ramus • Insertion: Midline connective tissue • Action: Supports pelvic floor TRANSVERSE PERINEI SUPERFICIAL • Origin: Ischial ramus • • Insertion: Central tendon of perineum Action: Fixes central tendon MUSCLES OF HIPS AND THIGHS ILIOPSOAS • Origin: Iliac fossa and vertebrae T12–L5 • Insertion: Lesser trochanter of femur and hip capsule • Action: Flexes hip GLUTEUS MAXIMUS • Origin: Posterior surface of ilium, sacrum, and coccyx • Insertion: Gluteal tuberosity of femur and iliotibial tract • Action: Extends hip; abducts and laterally rotates thigh GLUTEUS MEDIUS • Origin: Posterior surface of ilium • Insertion: Greater trochanter of femur • Action: Abducts and medially rotates thigh GLUTEUS MINIMUS • Origin: Posterior surface of ilium • Insertion: Greater trochanter of femur • Action: Abducts and medially rotates thigh TENSOR FASCIAE LATAE • Origin: Anterior superior iliac spine • Insertion: Through lateral fascia of thigh to lateral condyle of tibia • Action: Steadies femur on tibia through iliotibial tract when standing; flexes hip; medially rotates and abducts thigh 56 MUSCLES OF THE UPPER LEG ANTERIOR COMPARTMENT QUADRICEPS FEMORIS RECTUS FEMORIS • Origin: Ilium • Insertion: Tibial tuberosity via patellar ligament • Action: Extends knee; flexes hip VASTUS LATERALIS • Origin: Greater trochanter and linea aspera of femur • Insertion: Tibial tuberosity via patellar ligament • Action: Extends knee VASTUS MEDIALIS • Origin: Linea aspera of femur • Insertion: Tibial tuberosity via patellar ligament • Action: Extends knee VASTUS INTERMEDIUS • Origin: Body of femur • Insertion: Tibial tuberosity via patellar ligament • Action: Extends knee SARTORIUS • Origin: Anterior superior iliac spine • rotates thigh • Insertion: Medial side of tibial tuberosity • Action: Flexes hip and knee; laterally MEDIAL COMPARTMENT ADDUCTOR LONGUS • Origin: Pubis • Insertion: Linea aspera of femur • Action: Adducts and laterally rotates thigh; flexes hip ADDUCTOR MAGNUS • Origin: Pubis and ischium • Insertion: Femur • Action: Adducts and laterally rotates thigh; extends knee GRACILIS • Origin: Pubis near symphysis • Insertion: Tibia • Action: Adducts thigh; flexes knee POSTERIOR COMPARTMENT (HAMSTRING MUSCLES) BICEPS FEMORIS • Origin: → Long head—ischial tuberosity → Short head—femur • Insertion: Head of fibula • Action: Flexes knee; laterally rotates leg; extends hip SEMIMEMBRANOSUS • Origin: Ischial tuberosity • Insertion: Medial condyle of tibia and collateral ligament • Action: Flexes knee; medially rotates leg; extends hip SEMITENDINOSUS • Origin: Ischial tuberosity • Insertion: Tibia • Action: Flexes knee; medially rotates leg; extends hip LOWER LEG MUSCLES 57 ANTERIOR COMPARTMENT EXTENSOR DIGITORUM LONGUS • Origin: Lateral condyle of tibia and fibula • Insertion: Four tendons to phalanges of four lateral toes • Action: Extends four lateral toes; dorsiflexes and everts foot EXTENSOR HALLUCIS LONGUS • Origin: Middle fibula and interosseous membrane • Insertion: Distal phalanx of great toe • Action: Extends great toe; dorsiflexes and inverts foot TIBIALIS ANTERIOR • Origin: Tibia and interosseous membrane • Insertion: Medial cuneiform and first metatarsal bone • Action: Dorsiflexes and inverts foot FIBULARIS TERTIUS • Origin: Fibula and interosseous membrane • Insertion: Fifth metatarsal bone • Action: Dorsiflexes and everts foot POSTERIOR COMPARTMENT SUPERFICIAL GASTROCNEMIUS • Origin: Medial and lateral condyles of femur • Insertion: Through calcaneal (Achilles) tendon to calcaneus • Action: Plantar flexes foot; flexes leg SOLEUS • Origin: Fibula and tibia • Insertion: Through calcaneal tendon to calcaneus • Action: Plantar flexes foot DEEP FLEXOR DIGITORUM LONGUS • Origin: Tibia • Insertion: Four tendons to distal phalanges of four lateral toes • Action: Flexes four lateral toes; plantar flexes and inverts foot FLEXOR HALLUCIS LONGUS • Origin: Fibula • Insertion: Distal phalanx of great toe • Action: Flexes great toe; plantar flexes and inverts foot TIBIALIS POSTERIOR • Origin: Tibia, interosseous membrane, and fibula • Insertion: Navicular, cuneiforms, cuboid, and second through fourth metatarsal bones • Action: Plantar flexes and inverts foot LATERAL COMPARTMENT FIBULARIS BREVIS • Origin: Fibula • Insertion: Fifth metatarsal bone • Action: Everts and plantar flexes foot FIBULARIS LONGUS • Origin: Fibula • Insertion: Medial cuneiform and first metatarsal bone • Action: Everts and plantar flexes foot 58
