CARDIOVASCULAR SYSTEM: THE HEART (Chapter 14)
1. The heart is the central component of the cardiovascular system; its function is to propel blood through
the blood vessels.
B. Location and Size
1. The heart is a hollow, cone shaped organ that is about the size of a person’s closed fist.
2. It is located between the lungs in the mediastinum.
3. About two thirds of the heart’s mass lies to the left of the body's midline.
a) The pericardium is a triple layered sac that surrounds and protects the heart.
b) The outer layer is called the Fibrous Pericardium (structural for support)
c) The next layer is the Parietal layer of the Serous pericardium (is attached to the inner surface
of the Fibrous pericardium
d) The layer closest to the heart is called the Visceral layer of the Serous pericardium
e) Between the parietal and visceral layers is the Pericardial Cavity filled with serous fluid for
lubrication; allows freedom of movement during contractions of the heart muscle
D. Heart Wall
1. The wall of the heart consists of three layers:
i. outer epicardium is the Visceral layer of the serous pericardium
ii. thick, middle myocardium composed of cardiac muscle tissue that consists of cardiac muscle fibers
iii. inner endocardium composed of connective tissue covered by endothelium that is continuous with
the endothelium of the blood vessels
E. Chambers of the Heart
1. The two superior chambers are the right and left atria.
2. The two inferior chambers are the right and left ventricles. 3. The walls of the atria are relatively thin whereas the walls of the ventricles are relatively thick; the wall of
the left ventricle is two to four times thicker than that of the right ventricle.
F. Great Vessels of the Heart
1. The right atrium receives deoxygenated blood from three veins:
i. superior vena cava (SVC) brings blood from most parts of the body superior to the heart
ii. inferior vena cava (IVC) brings blood from all parts of the body inferior to the diaphragm
iii. coronary sinus receives blood from most of the vessels draining the wall of the heart
2. Blood in the right atrium flows into the right ventricle.
3. The right ventricle pumps blood into the pulmonary trunk which divides into the right and left pulmonary
4. Oxygenated blood returns from the lungs via four pulmonary veins that empty into the left atrium.
5. Blood in the left atrium flows into the left ventricle.
6. The left ventricle pumps blood into the ascending aorta.
7. The ascending aorta gives rise to the right and left coronary arteries which deliver blood to the walls of
8. The ascending aorta is continuous with the arch of the aorta, which is followed by the desce