Bio 473 Exam with Correct Solutions

Lung Mechanics - - muscles work to increase the volume of the lung and a pressure differential is created. As a result, air moves into the lungs. When atmospheric pressure is higher than intrapulmonary pressure, then air will enter the lungs (this is inhalation). - When intrapulmonary pressure is higher than atmospheric pressure, then air will leave the lungs (this is exhalation). Respiratory Control Center - the circuit of neurons in the base of the brain (the medulla oblongata and pons) that control the rate and depth of your breathing. Motor neurons leaving the respiratory control center innervate the diaphragm and chest muscles, causing them to contract and drive respiration. The respiratory control center also receives input from many other neurons. Peripheral Chemoreceptors - - monitor the carbon dioxide (CO2), hydrogen ion (ph), and oxygen (O2) concentrations in blood, and adjust the depth and rate of breathing accordingly. Carbon dioxide or CO2 is a waste product produced by all cells of the body during metabolism. Of the three chemicals listed, CO2 and H+ concentration have greatest impact on regulation of breathing. Hypercapnia - - a condition where the CO2 concentration in blood is too high - The carbonic acid equation will run forward, as all the reactants reach a new equilibrium, and H+ ion concentration increases. The increase in H+ ion concentration increases the acidity of your blood, and can cause the condition respiratory acidosis (when the blood is too acidic). Hypercapnia and respiratory acidosis usually occur together. The respiratory control center will respond by increasing how fast and deep you are breathing. This will cause CO2 to diffuse from your blood and into your lungs more rapidly. CO2 levels will decrease, the carbonic acid equation will run in reverse or to the left, and H+ ion concentration will decrease as well bringing the body back to a safe CO2 level and ph. Hypocapnia - a condition where CO2 concentration in blood is too low. In this case, the carbonic acid equation will run in reverse or to the right, and H+ ion concentration will decrease as a new equilibrium is reached. The decrease in blood H+ concentration will cause the blood to be less acidic. This condition is called respiratory alkalosis. Hypocapnia and respiratory alkalosis usually occur together. To correct the situation, the respiratory control center will decrease your respiratory rate. By breathing more slowly, CO2 from your cells will have a chance to build up in your bloodstream. The CO2 concentration will rise, and the carbonic acid equation will run forward again, reversing the respiratory alkalosis Hydrogen Levels in CSF - - The most important factor controlling respiration is the H+ ion concentration of the cerebrospinal fluid (CSF), the fluid bathing the brain. Central chemoreceptors found in the medulla oblongata of the brain monitor H+ ion concentration and function similarly to peripheral chemoreceptors found in large arteries. - High blood CO2 will translate to high H+ concentration in the CSF. Central chemoreceptors respond to the increased H+ ion concentration by generating more action potentials, which stimulate the respiratory control center. As the respiratory control center generates more action potentials in the motor neurons innervating the respiratory muscles, the respiratory muscles will contract harder and more often. Breathing rapidly allows more CO2 to diffuse out of the blood, into the lungs, and to be removed from the body during exhalation. This lowers the CO2 concentration of the blood and restores homeostasis. Spirometry - lung function test used to determine lung volumes