CHAPTER 11
The Cardiovascular System
1.
2.
Introduction
a. The cardiovascular system is much more than just the heart. It also includes blood vessels.
b. The major function of the cardiovascular system is transportation.
c. Using blood as the transport vehicle, the system carries oxygen, nutrients, cell wastes, hormones,
and many other substances vital for body homeostasis to and from the cells.
The Heart
a. Anatomy of the Heart
i. Location and Size
1. Size = approximately the size of a person’s fist; cone-shaped
2. Weight = less than a pound
3. Location = within the thorax and in between the lungs
4. Apex = pointed part of the heart that rests on the diaphragm and points toward the
left hip; where a stethoscope is placed to count the heart rate
5. Base = broader part of the heart; points toward the right shoulder and lies beneath
the second rib
ii. Coverings and Wall
1. 3 heart coverings:
a. PERICARDIUM = a double sac of serous membrane that encloses the
heart
b. EPICARDIUM = hugs the external surface of the heart and is part of the
heart wall.
c. PARIETAL PERICARDIUM = a loosely applied membrane that
anchors the heart to the diaphragm and sternum
2. 3 layers of the heart wall:
a. EPICARDIUM = described above
b. MYOCARDIUM = thick bundles of cardiac muscle that actually
contracts
c. ENDOCARDIUM = thin sheet that lines the heart chambers
iii. Chambers and Associated Great Vessels
1. The heart has 4 chambers = ATRIA
a. The superior atria are RECEIVING CHAMBERS
b. Blood flows into the atria from the veins of the body
2. The heart has 2 VENTRICLES
a. The inferior ventricles are DISCHARGING CHAMBERS
b. They pump the heart and blood is propelled out of the heart and into the
circulation
3. Although the heart is a single organ, it functions as a double pump.
a. The right side receives oxygen-poor blood from the veins of the body
through the large Superior and Inferior Venae Cavae.
b. Blood is then pumped through the Pulmonary Trunk.
c. The pulmonary trunk splits into right and left Pulmonary Arteries, which
carry blood to the lungs.
d. Oxygen-rich blood drains from the lungs and is returned to the left side of
the heart through the Pulmonary Veins.
e. The circulation from the right side of the heart to the lungs and back to the
left side of the heart is called PULMONARY CICULATION.
f. Blood returned to the left side of the heart is pumped out of the heart into
the Aorta (THE LARGEST ARTERY OF THE BODY).
g. The aorta branches out and supplies all body tissues with oxygen.
3.
h. Oxygen-poor blood circulates from the tissues back to the right atrium and
back into the superior and inferior vena cava.
i. The circulation from the left side of the heart through the tissues and back
to the right side of the heart is called SYSTEMIC CIRCULATION.
b. Physiology of the Heart
i. Cardiac Cycle:
1. In a healthy heart, the artria contract simultaneously. Then, as they start to relax,
contraction of the ventricles begin.
2. Systole - heart CONTRACTION
3. Diastole – heart RELAXATION
4. Most of the pumping work is done by the ventricles, so systole and diastole refer
to the contraction and relaxation of the ventricles
5. Cardiac Cycle – refers to the events of one complete heartbeat (when both atria
and ventricles contract and then relax)
a. Average heartbeat = 75 times per minute
b. Length of a normal cardiac cycle = 0.8 second
ii. Heart Sounds:
1. When using a stethoscope, you can hear 2 distinct sounds during each cardiac
cycle – HEART SOUNDS
2. The heart sound is “lub” and “dup” (lub-dup)
Blood Vessels
a. Blood circulates inside the blood vessels, which form a closed transport system = Vascular
System
b. Microscopic Anatomy of Blood Vessels
i. Arteries, Veins, and Capillaries
1. As the heart beats, blood is propelled into the large arteries leaving the heart.
2. It moves into smaller arteries and then into the arterioles.
3. The arterioles feed the capillary beds in the tissues.
4. Capillary beds are drained by venules.
5. Venules empty into veins that finally empty into the heart.
ii. Basically, arteries carry blood AWAY from the heart, and veins carry blood TO the heart.
c. Physiology of Circulation
i. A good indication of the efficiency of a person’s circulatory system can be obtained by
taking their pulse and blood pressure measurements.
ii. These measurements along with respiratory rate and body temperature are referred to as
VITAL SIGNS.
iii. Arterial Pulse
1. Pulse = a pressure wave that is caused by the expanding and recoiling of an artery
that occurs with each beat of the left ventricle
2. The average pulse is 70-76 beats per minute.
iv. Blood Pressure
1. Blood Pressure – the pressure the blood exerts against the inner walls of the
blood vessels
2. Measuring Blood Pressure
a. Systolic Pressure = the pressure in the arteries at the peak of ventricular
contraction
b. Diastolic Pressure = the pressure when the ventricles are relaxing
c. Blood pressure are reported with the systolic pressure written first
4.
5.
3. Effects of Various Factors on Blood Pressure
a. Exercise
b. Emotions
c. Water in the kidneys
d. Temperature
e. Chemicals/Drugs
f. Diet
Developmental Aspects of the Cardiovascular System
a. The heart begins as a tubelike structure that is beating and pumping blood by the 4th week of
embryonic development.
b. Congenital heart defects account for half of all infant deaths.
c. Gradual loss of elasticity in the arteries is an expected consequence of aging.
d. Cardiovascular disease is an important cause of death in individuals over age 65.
e. Modifications in diet, stopping smoking, and regular aerobic exercise may help to reverse the
loss of elasticity in the arteries and prolong life.
Disorders
a. Pericarditis – inflammation of the pericardium
b. Myocardial Infarction – heart attack
c. Fibrillation – a rapid uncoordinated shuddering of the heart muscle. It makes the heart totally
useless as a pump and is a major cause of death from heart attacks in adults.
d. Tachycardia – a rapid heart rate (over 100 beats per minute)
e. Bradycardia – a slow heart rate (less than 60 beats per minute)
f. Murmurs – abnormal or unusual heart sounds
g. Varicose Veins – common in people who stand for long periods of time and in obese
individuals. Blood collects in the feet and legs.
h. Hypotension – low blood pressure
i. Hypertension – high blood pressure
j. Coronary Artery Disease – the filling of the blood vessels with fatty, calcified deposits