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University of California - Irvine
Biological Sciences
Peter A.Bowler

11/19/12 e109 lecture 20 Blood transfusion article -patients receiving blood were more likely to have a heart attack: due to the dramatic deficiencies in levels of nitric oxide (NO) b/c within hours of leaving the body, the research showed that a unit of blood loses up to 70% of its NO by the time the blood reaches its “use by” expiration date 42 days later Oxygen is not very soluble in water. Hemoglobin increases the solubility of oxygen in blood (made mostly of water). Hemoglobin is inside red blood cells. -Hemoglobin is a protein that has 4 Heme groups. Each Heme group has iron at the center (that’s what reversibly binds to oxygen). Each heme group can bind to one oxygen molecule for a total of 4 oxygen molecules can reversibly bind to every hemoglobin molecule. -Hemoglobin reversibly binds to oxygen (that’s how it makes oxygen much more soluble in blood). Without hemoglobin, the oxygen-carrying capacity of our blood would be very low. Fig 18-2 Gases diffuse down partial pressure gradients -Individual gas components will diffuse from areas of higher partial pressure to areas of lower partial pressure -oxygen and carbon dioxide partial pressures are different outside from in the alveoli -partial pressure of oxygen is 100 mmHg in the alveoli and 40 mmHg for carbon dioxide partial pressure in the alveoli -when you exhale, there’s still some residual/stale air in your respiratory system (residual volume) that has an increased amount of carbon dioxide mixes with the air that is being brought into the alveoli---this is why the levels are lower in the alveoli -Venous blood levels: 40 mmHg for P02 and 46 mmHg for PCO2 PCO2 diffuses out because lower in the alveoli (moves from higher to lower partial pressure), and oxygen moves from alveoli to capillary bed to artery -Arterial blood levels: P02=100mmHg and PCO2 = 40mmHg -changes in chemical components of the blood (diffusion) only happen at the capillary beds— stays at a constant level until it reaches the capillary bed, where it will change Tissue levels: P02 =40mmHg and PCO2 = 46mmHg, so carbon dioxide diffuses out of the tissues into the capillaries via systemic circulation, and oxygen flows from capillaries to the tissue cells Your question: If there are several gas components in the air, why is oxygen the only
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