The Muscular System
Structure and function of the cardiovascular system
Capillaries
Blood flows away from the heart to arteries, which follow into arterioles, and then narrow further into capillaries. After the tissue has been perfused, capillaries branch and widen to become venules and then widen more and connect to become veins, which return blood to the heart
They are so thin that blood cells can only pass through them in single file. The exchange of oxygen and carbon dioxide takes place through the thin capillary wall. The red blood cells inside the capillary release their oxygen which passes through the wall and into the surrounding tissue. The tissue releases its waste products, like carbon dioxide, which passes through the wall and into the red blood cells.
Capillaries play an important role in micro circulation. Micro circulation deals with the circulation of blood from the heart to arteries, to smaller arterioles, to capillaries, to venules, to veins and back to the heart. http://biology.about.com/od/anatomy/ss/capillary.htm
[PICTURE]Blood vessels are hollow utensils for carrying blood. Located throughout your body, your blood vessels are hollow tubes that circulate your blood. There are three varieties of blood vessels: arteries, veins, and capillaries. During blood circulation, the arteries carry blood away from the heart. The capillaries connect the arteries to veins. Finally, the veins carry the blood back to the heart.
Besides circulating blood, the blood vessels provide two important means of measuring vital health statistics: pulse and blood pressure. We measure heart rate, or pulse, by touching an artery. The rhythmic contraction of the artery keeps pace with the beat of the heart. Since an artery is near the surface of the skin, while the heart is deeply protected, we can easily touch the artery and get an accurate measure of the heart's pulse. www.fi.edu/learn/heart/vessels/vessels.html
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A03.2 Unit 1 Mr Evans
