CHAPTER 8-THE CARDIOVASCULAR SYSTEM
I. The Cardiovascular System consists of the heart and the blood vessels. The heart functions by
pumping blood to the body through blood vessels.
II. Types of Blood Vessels:
A. Arteries-carry oxygenated blood away from the heart.
1. Blood is pushed through arteries by the pumping action of the heart.
2. Arteries must be strong and flexible to accommodate the pulses of blood
propelled through the arteries by the heart.
3. Layers in the Walls of Arteries
a. Tunica Externa-outer covering, composed of connective and elastic tissue.
1) This layer provides strength and flexibility to the artery.
b. Tunica Media-middle layer, composed of smooth muscle.
1) This layer is involved in vasoconstriction (narrowing the artery)
and vasodilation (opening the artery).
2) The tunica media regulates blood flow to organs and tissues in the
body.
c. Tunica Intima-inner layer, composed of endothelium (epithelial tissue).
1) This layer surrounds the lumen (hole) in the artery.
4. Pulse-the surge of blood felt in the arteries when blood is pumped from the
heart. Measuring pulse can provide evidence on heart activity.
B. Capillaries-microscopic blood vessels located throughout the body.
1. These connect arteries and veins.
2. Capillaries are the only sites where materials can be exchanged between the
body and the blood. Capillaries are only one cell layer thick so materials can
easily diffuse between the blood and body tissues.
C. Veins-carry deoxygenated blood back to the heart from the body.
1. Veins are typically collapsible.
2. The walls of veins are composed of the same layers as arteries; however, veins
are typically not as thick as arteries.
3. Blood pressure is usually low in veins. To ensure that blood moves forward, veins
contain valves. Valves ensure that blood does not move backwards.
III. THE HEART-serves as the major pump for the body.
A. The heart is about the size of a closed fist.
B. The Pericardium-protective sac that covers and protects the heart. Can you translate the
term pericardium?
1. The Pericardium is composed of two layers:
a. Parietal Pericardium-outer layer, protects the heart.
b. Visceral Pericardium-inner layer, attaches directly to the heart.
1) Pericardial Cavity-space between the above two layers; this
cavity is filled with a lubricating fluid known as pericardial fluid.
C. Layers of the Heart Wall
1. Epicardium-is the same thing as the pericardium.
2. Myocardium-thickest layer, contains cardiac muscle.
3. Endocardium-inner layer, forms a membrane that lines the chambers and covers
the heart valves. Can you translate each of these terms?
D. The heart is divided into right and left sides by the septum.
1. The right side of the heart pumps deoxygenated blood to the lungs.
2. The left side of the heart pumps oxygenated blood to the tissues of the body.
E. Internally, the heart is divided into four distinct chambers.
1. 2 upper, smaller atria (right and left).
2. 2 lower, larger ventricles (right and left).
3. These chambers are separated from each other by septa (interatrial septa,
interventricular septa).
F. Blood flows through the heart in only one direction. This flow is regulated by valves in
the heart. Valves prevent blood from flowing backwards.
G. Types of Heart Valves:
1. Semilunar Valves-located between the ventricles and certain arteries attached to
the heart. 2 Types of Semilunar Valves:
a. Pulmonary Valve-between the right ventricle and the pulmonary artery.
b. Aortic Valve-between the left ventricle and the aorta.
2. Atrioventricular Valves-located between the atria and ventricles. 2 Types:
a. Tricuspid Valve-located between the right atrium and right ventricle.
b. Bicuspid (Mitral) Valve-located between the left atrium and left ventricle.
H. Circulatory Patterns Associated with the Heart:
1. Coronary Circulation-carries blood to and from the heart muscle. Coronary
arteries are associated with this circulatory pattern.
2. Pulmonary Circulation-carries deoxygenated blood from the right side of the
heart to the lungs where gas exchange can occur. Pulmonary arteries carry
deoxygenated blood from the right ventricle to the lungs and the pulmonary veins
return oxygen-rich blood to the left atrium of the heart.
3. Systemic Circulation-carries oxygenated blood from the left side of the heart to
the cells of the body.
a. Blood exits the heart via the aorta and is carried to tissues by arteries,
arterioles and capillaries. Blood is returned to the right atrium by venules
veins (the vena cava actually empties the blood into the right atrium).
4. Fetal Circulation-blood bypasses the pulmonary circulation in a developing
fetus. Why is this so?
a. Foramen ovale-a small hole between the atria, allows blood to flow from
the right atrium to the left atrium.
I. Cardiac Conduction System-a collection of nerve cells that act to set the rhythm of the
heart. The Sinoatrial Node is part of this system and it acts to set the pace of the heart.
1. Impulses move from the SA node to the Atrioventricular Node and eventually
to the Bundle of His. This guarantees that entire heart contracts in an efficient
fashion.
IV. BLOOD PRESSURE-measurement of the force of blood moving against the walls of arteries.
A. Systole-a contraction phase in the heart.
B. Diastole-a relaxation phase in the heart.
C. BP is expressed as a ratio of systolic pressure over diastolic pressure.
D. Normal BP is usually near 120/80 mm Hg. It is measured with a sphygmomanometer.
E. Hypertension-high blood pressure. What are some factors that can lead to hypertension?
1. How can hypertension be treated?
V. MEDICAL WORD ELEMENTS-pages 216-219.
VI. PATHOLOGY
A. Arteriosclerosis
B. Coronary Artery Disease
C. Endocarditis
D. Varicose Veins
E. Heart diseases can lead to dyspnea (difficulty breathing), syncope (fainting), angina (chest
pain), or arrhythmias (heart irregularities).
VII. DISEASES/CONDITIONS/PROCEDURES-pages 223-236.
VIII. PHARMACOLOGY-pages 237-238.