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Respiratory Physiology Through the use of the Kidneys and the Respiratory System, the Medulla Oblongata has control over the body's pH. pH, a measure of acidity where 7 is neutral, and a range from 1, extremely acidic, to a basic, alkaline, 14. pH in the body must be 7.4 with a range from 7.35-7.45. The respiratory system is the primary method for monitoring and correcting any problems in our pH. Carbon dioxide, the waste product of our cells, is hydrophobic and therefore unable to be dissolved well in plasma, which is mainly water. Carbon dioxide changes to carbonic acid which breaks down into bicarbonate in the following reaction: CO2
+ H2O à
H2CO3 àH+
+ HCO3 Bicarbonate is hydrophilic and easily dissolves in the plasma. Not all of the carbonic acid completely breaks down to bicarbonate, allowing the general trend to be made that more carbon dioxide results in more carbonic acid which consequently has a higher acidity. When acidity increases, respiratory rate increases as well to dispose of the extra acid. If the blood's pH is basic, respiratory rate decreases to hold the carbon dioxide in the blood until the pH has resumed 7.4. On a physical level, the lungs are attached inside the chest cavity. Intercostals allow the chest cavity to expand and relax into it's normal position. As the diaphragm relaxes it curls underneath the ribs. Contraction of the diaphragm pulls it down and increases the size of the chest cavity, respectively increasing the size of the lungs. Air flows into the lungs to fill the empty space. Thus inspiration occurs. The diaphragm relaxes into it's normal position and expiration releases carbon dioxide and water into the air. The involuntary action of breathing is not a response to a necessity of oxygen, but a change to monitor the amount of carbon dioxide in the body. Gas exchange occurs between the alveoli in the lungs and small pulmonary capillaries. Hydrophobic gases, lipid soluble, are permitted to move between the alveoli and capillaries by passive diffusion. Oxygen, with a higher concentration in an alveolus, moves down the concentration gradient and into the capillaries. Carbon dioxide flows from the capillaries, an area of higher concentration, into the alveolus. |