Answer to Question 1
ANS: A
After phagocytosis by the splenic macrophages, hemoglobin is released. It is broken down into its component parts of globin chains and heme. Heme is further degraded in a series of steps eventually forming bilirubin, which is taken to the liver and further processed. Globin chain amino acids are returned to the amino acid pool for use in protein synthesis.
Answer to Question 2
ANS: A
Red cells have a high concentration of potassium and a low concentration of sodium when compared with the plasma environment. To maintain this difference in gradient, adenosine triphosphate (ATP)-dependent enzymes are needed. When this system fails, sodium increases and potassium falls in the red cells. This results in loss of selective permeability of the red cell membrane, and water enters the cell causing it to sphere. Senescence is a normal aging process that eventually leads to red cell phagocytosis by splenic macrophages.
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