Lab #7- Formal- Intro, Materials, and Methods

Lab #7- Formal- Intro, Materials, and Methods - Sylwester...

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Sylwester Czado 11-8-07 BIO 244, Lab #7 TA: Shannon Gerry Introduction The respiratory center in the medulla oblongata consists of nerve cells at the base of the brain which controls breathing. It sends impulses to the nerves in the spinal cord that regulates the diaphragm and the muscles between the ribs for inhalation. All living animals must take in oxygen and get rid of carbon dioxide through gas-exchange organs called lungs. The lungs provide a place where oxygen can reach the blood and carbon dioxide can be removed from it. The level of carbon dioxide in the blood determines the rate at which humans breathe. When the level of carbon dioxide rises, rapid and deeper breathing occurs. However, when the level drops, breathing slows down. (Compton’s Interactive Encyclopedia) The respiratory center is connected with most of the sensory nerves of the body so any stimulation of the nerves can change breathing. Humans breathe by first taking air into the lungs (inspiration) and then expelling it (expiration). The average adult normally takes about 16 breaths per minute when awake and about six to eight per minute when asleep. Under stress, the rate may increase to about 100 breaths per minute to supply the increased oxygen demand. Even if the lung capacity is around 300 cubic inches (4,916 cubic centimeters), the volume of air in a normal breath averages only about 30 cubic inches (492 cubic centimeters). The lungs never empty completely. Even after vigorous expiration, they still contain about 60 cubic inches (983 cubic centimeters) of air. Also, human lungs can hold about four quarts (3.8 liters) of air. (Cowens)
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The mechanics of breathing depends on the chest cavity. It is formed by the rib cage, the attached muscles, and the diaphragm. The two lungs and heart are inside the chest cavity. One lung is on either side of the heart. The right lung has three lobes and the
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Lab #7- Formal- Intro, Materials, and Methods - Sylwester...

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