RBCs are biconcave discs that lack mitochondria, ribosomes, and nuclei, and they contain a large amount of hemoglobin. RBCs transport oxygen, while WBCs are involved in immunity. The five types of WBCs vary in size from slightly lager to twice the diameter of an RBC, contain a prominent nucleus, and may contain granules with distinct staining properties. 24. How do elements of blood defend against toxins and pathogens in the body? WBCs defend against toxins and pathogens, Neutrophils, eosinophils, and monocytes engulf and digest bacteria, protozoa, fungi, viruses, and cellular debris.
Lymphocytes specialize to attack 25. What is the role of blood in the stabilization and maintenance of body temperature? Blood stabilizes and maintains body temperature by absorbing and redistributing the heat produced by active skeletal muscles. Dermal capillaries dilate when body temperature rises, thereby increasing blood flow to the skin and dissipating the excess heat into the air. Dermal capillaries constrict when body temperature falls, thereby decreasing blood flow to the skin and conserving heat for internal organs that are more temperature sensitive. 26. Describe the structure of hemoglobin.
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How does the structure relate to its function? Each molecule of hemoglobin consists of four protein subunits, each of which contains a single molecule of heme, a non-protein ring surrounding an iron ion. These central iron ions are what actually pick up and release oxygen molecules. 27. Why is aspirin sometimes prescribed for the prevention of vascular problems? Aspirin helps prevent vascular problems by inhibiting clotting. It inactivates platelet enzymes involved in the production of thromboxanes and prostaglandins, and it inhibits endothelial cell production of prostacyclin.