Epicardial Versus Subendocardial Coronary Blood Flow Effect of Intramyocardial Pressure Figure 215 demonstrates

Subendocardial Vessels
Diagram of the epicardial, intramuscular, and subendocardial coronary vasculature.

the special arrangement of the coronary vessels at different depths in the heart muscle, showing on the outer surface epicardial coronary arteries that supply most of the muscle. Smaller, intramuscular arteries derived from the epicardial arteries penetrate the muscle, supplying the needed nutrients. Lying immediately beneath the endocardium is a plexus of subendocar-dial arteries. During systole, blood flow through the subendocardial plexus of the left ventricle, where the intramuscular coronary vessels are compressed greatly by ventricular muscle contraction, tends to be reduced. But the extra vessels of the subendocardial plexus normally compensate for this. Later in the chapter, we will see that this peculiar difference between blood flow in the epicardial and subendocardial arteries plays an important role in certain types of coronary ischemia.

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Essentials of Human Physiology

Essentials of Human Physiology

This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.

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