Red Blood Cells: SAQ Solutions

Below are the solutions to the Red Blood Cells Self-Assessment Questions:

1. Any short answer mentioning the following will be accepted:
   • Maximizes surface area for gas exchange (oxygen and carbon dioxide transport)
   • Diffusion of gases into cell quickly
   • Thin structure allows it to bend easily in narrow regions, such as capillaries
     Form follows function! Red blood cells are used to transport oxygen to tissues from the lungs and carbon dioxide from the tissues to the lungs. They also must be able to move through the whole vasculature, so the thin, flexible structure is important for this.
2. A and D. It is equal to the packed cell volume/ total blood volume, and it describes the amount of hemoglobin in whole blood. These two statements are NOT true. 
   The MCHC describes the amount of hemoglobin in red blood cells (choice C).  The formula to find this is correctly given in choice B.
3. Increased destruction of RBCs: hereditary spherocytosis, sickle cell anemia. Decreased ability to form RBCs: iron-deficiency anemia, aplastic anemia.
   Anemia is defined as a hematocrit that is less than 0.25. In both the case of increased RBC destruction and decreased ability to form RBCs, a lower RBC count will decrease the hematocrit and consequently result in anemia should this number drop below 0.25.