Functions of Human Circulatory System
Chp. 8
Includes transport of:
1. oxygen
2. carbon dioxide
3 nutrients
4. water
5. ions
6. hormones
7. antibodies
8. metabolic wastes
The Human Circulatory System
•
•
•
•
4 chambered heart
Arteries
Capillaries
Veins
Arteries
• muscular vessels carrying blood away
from heart
• carry oxygenated blood
– Exception- pulmonary artery (to lungs)
Capillaries
•
•
•
•
thin walled (one cell layer) vessels
arise from arterioles (tiny arteries)
form capillary beds
all exchange between blood & cells occurs here
Veins
• Venules receive blood from the capillaries
• Low oxygenated blood transferred to veins
• Veins carry low O2 blood to heart
– Exception- pulmonary vein carries oxygenated blood
• Thin walled & flattened
• Nearer to body surface than arteries
Circulation Through Human Heart
Body blood enters RIGHT SIDE of HEART
Right atrium ----> right ventricle ----> Pulmonary artery
----> alveoli in lungs----> oxygenated blood --> Pulmonary
Veins ---->
Left Atrium. ----> Left Ventricle ----> blood leaves through
Aorta (first artery) ---> flows to body
Control of the Heart
1. Extrinsic (outside)
2. Intrinsic (within)
Extrinsic (outside)
control of heart beat
• autonomic nervous system
• adrenal hormone epinephrine
• heart itself can secrete regulatory hormones when
changes in blood pressure in the atria are detected.
Intrinsic (within) control
• Origin of heart beat
– Sinoatrial (SA) node ( pacemaker)
• May be influenced by autonomic nervous
system
Human Circulatory System
Circuits
1.
Hepatic Portal Circuit
2.
Renal Circuit
3.
Cardiac Circuit
4.
Systemic Circuit
Capillaries
•
•
•
•
composed of interlocking cells
one cell thick
nutrients, ions, water, & oxygen diffuse here
Blood moves from capillary to a venule, picks up:
• ions
• Water
• carbon dioxide
• metabolic wastes
• nutrients from intestine
Materials leave capillaries by three mechanisms:
1. Diffusion
2. Hydrostatic pressure
3. Pinocytosis
Veins
•
Entering blood volume equals that leaving arteries
•
blood pressure is much lower than in arteries
Movement through veins assisted by:
1)
one way flap-like valves allow blood to move in one
direction (toward heart)
2)
some smooth muscle around larger veins that
contracts and moves blood
3)
limb and breathing movements literally massages
veins and squeezes blood along
Arterioles and Capillaries
Figure 8.2
Capillary Structure
Figure 8.4
Lymphatic System
• Function: maintain blood volume; also functions
in immune system
• Structure
– Blind-ended capillaries
– Lymphatic vessels
– Lymph
The Heart
Figure 8.8
The Heart
•
•
•
•
Structure
Layers; epicardium, myocardium, endocardium
Chambers: two atrias, two ventricles
Valves
– Two atrioventricular valves: tricuspid and
bicuspid (mitral)
– Two semilunar valves: pulmonary and aortic
Pulmonary Circuit: Oxygenation of
Blood
– Deoxygenated blood through the vena cava to the
right atrium
– Deoxygenated blood through the right atrioventricular
valve to the right ventricle
– Deoxygenated blood through the pulmonary
semilunar valve to the pulmonary trunk and the lungs
– Oxygenated blood through the pulmonary veins to the
left atrium
– Oxygenated blood through the left atrioventricular
valve to the left ventricle
Systemic Circuit: Delivery of
Oxygenated Blood to Tissues and Return
of Blood to the Heart
– Oxygenated blood through the aortic semilunar valve
to the aorta
– Oxygenated blood through branching arteries and
arterioles to the tissues
– Oxygenated blood through the arterioles to capillaries
– Deoxygenated blood from capillaries into venules and
veins
– Ultimately to the vena cava and into the right atrium
Cardiac Cycle
Figure 8.12
Heart Sounds and Heart Valves
• Lub-dub
• Heart murmurs
Cardiac Conduction System
Coordinates Contraction
• SA node: cardiac
pacemaker
• AV node: relay
impulse
• AV bundle and
Purkinje fibers:
carry impulse to
ventricles
Figure 8.14
Electrocardiograms (EKG/ECG)
• Three formations
– P wave: impulse across atria
– QRS complex: spread of impulse down septum,
around ventricles in Purkinje fibers
– T wave: end of electrical activity in ventricles
• Arrythmias, ventricular fibrillation
Electrocardiograms (EKG/ECG)
(cont.)
Figure 8.15B, C
Blood Pressure
• Definitions: “normal”
– Systolic pressure
– Diastolic pressure
• Measurement: sphygmomanometer
Blood Pressure
• Hypertension: high blood pressure
– Definition
– The silent killer
– Risk factors
• Hypertension: blood pressure too low
– Clinical signs: dizziness, fainting
– Causes: orthostatic, severe burns, blood loss
Regulation of the Cardiovascular
System: Baroreceptors
• Baroreceptors: pressure receptors in aorta and
carotid arteries
• Steps in mechanism
– Blood pressure rises, vessels stretched
– Signals sent to brain in the cardiovascular center
– Heart signaled to lower heart rate and force of
contraction
– Arterioles vasodilate, increasing blood flow to tissues
– Combined effect lowers blood pressure
Regulation of the Cardiovascular
System: Nervous and Endocrine
Factors
• Medulla oblongata signals
– Sympathetic nerves: constrict blood vessels,
raising blood pressure
– Parasympathetic nerves: dilate blood vessels,
lowering blood pressure
• Hormones: epinephrine (adrenaline)
• Local requirements dictate local blood flow
Cardiovascular Disorders
• Angina pectoris: A warning
• Myocardial infarction/heart attack: permanent
cardiac damage
• Congestive heart failure: decrease in pumping
efficiency
• Embolism: blockage of blood vessels
• Stroke: impaired blood flow to the brain
Reducing the Risk of Cardiovascular
Disease
• Smoking: Don’t
• Blood lipids: monitor cholesterol levels
• Exercise: regular and moderate
• Blood pressure: treat hypertension
• Weight: being overweight increases risk of heart
attack and stroke
• Control of Diabetes Mellitus: early diagnosis and
treatment delays onset of related problems
• Stress: avoid chronic stress
Cardiac Anatomy Quiz
1
3
5
9
10
11
12
2
4
6
7
8
13
14
15
Test Yourself, page 172
Blood
• Connective tissue
• plasma matrix + 3 types cells
Plasma = 90% water + 10% plasma solids.
Solids include:
urea
amino acids
glucose
hormones
ions
fats
proteins
The 3 Major Blood Proteins
albumins - large proteins that bind impurities &
some toxins, aid in transport of
hormones, fatty acids and ions, help
maintain osmotic balance.
globins - include antibodies (immunoglobins)
fibrinogen - important in blood clotting
Blood Cells
A) Erythrocytes
B)
Leukocytes
C) Platelets
Erythrocytes (red blood cells)
1.
2.
3.
4.
5.
6.
7.
small, disk-like shape
no nucleus
cannot reproduce
last 4 months then rupture
produced by red bone marrow
contain hemoglobin
carry oxygen
Leukocytes (white blood cells)
• Nucleus present
• Active in immune system
•
•
•
•
most are neutrophils that engulf microorganisms
Basophils
Eosinophils
lymphocytes
Platelets (thrombocytes)
•
•
•
•
tiny
numerous
cell fragments
aid blood clotting
Circulatory system + lymphatic system =
Proper Osmotic Conditions
Three Fluid Regions Of Body
1) fluid of blood and lymph
2) interstitial fluid - watery fluid between and among cells
3) intracellular fluid