Internal Transport and Gas Exchange

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Blood delivers nutrients and oxygen to all parts of the body. It is able to do this because of the circulatory system inside the body. The heart beat pumps blood throughout the body. As the blood is pumped, it travels through the body by the means of a circulatory system. The circulatory system is composed of a system of blood vessels. The vessels are elastic tubes, which vary in diameter, that carry blood to all parts of the body (Solomon, Berg, & Martin, 2008).
Arteries, capillaries, and veins are the three main types of blood vessels. These blood vessels make up the vascular system in the body. An artery is a blood vessel that has a thick muscular and elastic wall and a large diameter. The main function of an artery is to carry blood that is rich in oxygen away from the heart to all parts of the body. The aorta is the main artery of the heart. All blood that leaves the heart is fed through the aorta to the rest of the body. As the aorta starts to get farther away from the heart, the diameter of the blood vessel starts to decrease and it begins to branch off. It branches into arterioles which are just smaller arteries (Clinic, 2014).
The arterioles do not stay the same diameter as they make their way through the body. They are eventually branched into smaller blood vessels called capillaries. Capillaries are blood vessels that have a diameter about the size of a piece of hair. The walls of the capillaries are extremely thin. They are only about one cell thick. This allows for an easy exchange of substances between the capillaries and other tissues/cells of the body (Clinic, 2014).
Capillaries are the bridge between arterioles and venules. The branching network of the capillaries is called a capillary bed, and this is what ...

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Another exception to the vascular system is how certain areas of the body channel the blood back into the venules. The brain, for example, has the blood enter large dural sinuses (cavities) instead of the usual venules after the gas and nutrient exchange has occurred. An other example is the blood that drains from the digestive organs. This blood has to first flow through the liver to be filtered before it can retrun to the normal systemic circulation (Marieb, 2001).

Works Cited

Cleveland Clinic. (2014). How Does Blood Travel Through Your Body? Retrieved on February 18, 2014 from http://my.clevelandclinic.org/heart/heart-blood-vessels/how-does-blood-travel-through-body.aspx

Marieb, E. N. (2001). Human Anatomy and Physiology (5th ed.). USA: Benjamin Cummings.

Solomon, E. P., Berg, L. R., & Martin, D. W. (2008). Biology (8th ed). USA: Thomson Brooks/Cole.

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