• Where is my heart located?
• What is its purpose?
• How is the heart supplied with oxygen and nutrients?
• What do the terms angina and myocardial infarction mean and how do they differ?

Figure 1. The heart and major structures

The heart (figure 1 ) can be described as a right and left sided pump that is positioned in the center of your chest and extends into the left side of your chest. The bottom of your heart sits just above the diaphragm and your lungs surround the heart on the sides. The right side receives blood (that is depleted of oxygen) from your body then pumps it forward into your lungs. The left side of your heart receives blood from your lungs (now enriched with oxygen) and pumps it back to your muscles, brain, kidneys, etc On the average your heart circulates 8-10 quarts of blood per minute. Despite this enormous blood flow through it, the heart is unable to obtain the oxygen and nutrients needed to function from this source of blood. Three major arteries (right coronary artery, left circumflex, left anterior descending) arise from the aorta which is the major blood vessel leaving the left side of the heart. These arteries then branch out supplying oxygen and nutrients to various regions of your heart. The location of the arteries are Illustrated in figure 2.

Figure 2. The coronary arteries.

The movement of blood through the heart is dependent, in part, on its four valves (tricuspid, mitral, pulmonary, aortic) (see figure 1). They are located between the atria (blood receiving chambers) and the ventricles (major pumping chambers); and between the ventricles and the blood vessels leaving the heart (on the right side this is the pulmonary artery, on the left side is the aorta).

To coordinate the heart's pumping, it has a built in electrical conduction system. The heart is a muscle and, like other muscles, it contracts (shortens) when stimulated. The heart is unlike other muscles in that it can self generate impulses to stimulate itself along with surrounding muscle cells. The electrical system of the heart keeps its chambers beating in rhythmic sequence so blood is continually pumped through it to all parts of the body.

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