Chapter 15: Cardiovascular System
I. Introduction
A. The cardiovascular system includes the heart and blood vessels. B. Without blood circulation, the tissues lack oxygen and nutrients and waste accumulates.
II. Structure of the Heart
A. Size and Location of the Heart 1. An average size of an adult heart is generally 14 cm long and 9 cm wide. 2. The heart is bounded laterally by the lungs, anteriorly by the sternum, and posteriorly by the vertebral column. 3. The base of the heart lies beneath the second rib. 4. The apex of the heart is at the level of fifth intercostal space. B. Coverings of the Heart 1. The pericardium is a covering that enclosed the heart and the proximal ends of the large blood vessels to which it attaches. 2. The fibrous pericardium is the outer fibrous layer of the pericardium. 3. The visceral pericardium is a serous membrane that is attached to the surface of the heart. 4. The parietal pericardium is a serous membrane that lines the fibrous layer of the pericardium. 5. The pericardial cavity is the space between the visceral pericardium and parietal pericardium. 6. Serous fluid reduces friction between the pericardial membranes as the heart moves. C. Wall of the Heart 1. The three layers of the heart wall are endocardium, myocardium, and pericardium. 2. The epicardium is composed of a serous membrane that consists of connective tissue covered by epithelium, and it includes blood capillaries, lymph capillaries, and nerve fibers. 3. The middle layer is the myocardium. 4. The myocardium is composed of cardiac muscle tissue. 5. The inner layer is the