Lymphatic Disorders

Gas Transport Page 1. Introduction The blood transports oxygen and carbon dioxide between the lungs and other tissues throughout the body. These gases are carried in several different forms 1. dissolved in the plasma 2. chemically combined with hemoglobin 3. converted into a different molecule Page 2. Goals To explore how oxygen is transported in the blood. To explore how carbon dioxide is transported in the blood. To understand the effect of variables, such as PO2 and PCO2, on oxygen and carbon dioxide transport. Page 3. Oxygen Transport Transport of oxygen during external respiration With its low solubility, only approximately 1.5 of the oxygen is transported dissolved in plasma. The remaining 98.5 diffuses into red blood cells and chemically combines with hemoglobin. Label this diagram Page 4. Hemoglobin Within each red blood cell, there are approximately 250 million hemoglobin molecules. Each hemoglobin molecule consists of 1. A globin portion composed of 4 polypeptide chains. 2. Four iron-containing pigments called heme groups. Each hemoglobin molecule can transport up to 4 oxygen molecules because each iron atom can bind one oxygen molecule. When 4 oxygen molecules are bound to hemoglobin, it is 100 saturated when there are fewer, it is partially saturated. Oxygen binding occurs in response to the high partial pressure of oxygen in the lungs. When hemoglobin binds with oxygen, it is called oxyhemoglobin. When one oxygen binds to hemoglobin, the other oxygen molecules bind more readily. This is called cooperative binding. Hemoglobins affinity for oxygen increases as its saturation increases. Label this diagram Page 5. Oxyhemoglobin and Deoxyhemoglobin The formation of oxyhemoglobin occurs as a reversible reaction, and is written as in this chemical equation In reversible reactions, the direction depends on the quantity of products and reactants present. In the lungs, where the partial pressure of oxygen is high, the