A Transcript of the Interpreted Excerpt of The Cardiovascular System in English

This is the transcript of the portion of the technical lecture interpreted by Patty McCutcheon. For a more print friendly version and to see it in context, download the PDF file from To the Heart of the Matter .

This lecture will focus on the cardiovascular system, one of twelve or so major organ systems in your body. The cardiovascular system is the primary transportation system in your body. When glucose travels around your body from your liver to your toe, for example, it is your cardiovascular system that is responsible. When oxygen travels from your heart to your brain, it is the cardiovascular system that’s responsible for that transport also. The two basic components of the cardiovascular system are the heart, which is the centralized pump and then miles and miles of hollow tubes that carry blood, that we technically know as blood vessels, or veins, arteries, capillaries, and several different types. Today, we are going to focus primarily on the heart.

In order to understand the heart, we are going to have to understand first of all what the heart is made of. All organs in the body are made of small living units called cells. The heart is completely made up of living cells known as cardiac muscle cells. These cells are unique because they are found no where else in the body. Cardiac muscle cells, like most muscle cells, have the ability to shorten or contract. There are however, several properties that make cardiac muscles cells relatively unique. First of all, cardiovascular muscles cells are said to be autorhythmic. That’s a special property that means they can generate their own action potential, or own electrical activity without relying on the brain or the spinal cord. For example, if a heart is removed during a heart transplant operation, the heart will continue to beat after all connections are severed. We’ll talk about this autorhythmicity in a moment. Cardiovascular cells are also able to stimulate adjacent cells. For example, to activate all of the cells in the heart, all
of the millions of cells in the heart, its only necessary to stimulate two or three of them. These waves of action potential, or waves of electrical current, can travel to adjacent cells.

The heart is a round organ, roughly the size of a small grapefruit, and it contains four hollow spaces, internally. The walls of the heart are made of these cardiovascular muscle cells, but the internal chambers are known as atria or ventricles. The heart has a couple of different primary functions. It will receive blood that’s deoxygenated, that’s flowing from the brain for example, or from the pancreas, or from your little toe. The heart will then send that blood up to your lungs so it can saturate itself with oxygen. Blood will return to the heart, and last but not least, the heart has the responsibility of sending this oxygenated blood out to every single tissue in the body.

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