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Chapter 11. Immune System

Select the nonspecific functional division of the immune system.

a. Innate

b. Adaptive

c. Granulocytes

d. Lymphocytes

Answer a is correct. The innate immune system is the nonspecific functional division of the immune system. There are two functional divisions, innate (nonspecific) and adaptive (specific).

Answer b is incorrect. While the adaptive immune system is a functional division of the immune system, it is the specific division.

Answer c is incorrect. Granulocytes are WBCs that make up part of the innate (nonspecific) immune system.

Answer d is incorrect. Lymphocytes are WBCs that make up part of the adaptive (specific) immune system.

Select the innate cell that represents the majority of granulocytes and serves as the primary defense against bacterial infections.

a. Lymphocytes

b. Neutrophils

c. Monocytes

d. Eosinophils

e. Basophils

Answer b is correct. Neutrophils represent the majority of granulocytes (80%-90%) and leukocytes (40%-70%) and serve as the primary defense against bacterial infections. Neutrophils, also termed as segs or polymorphonuclear cells, migrate from the bloodstream into infected or inflamed tissue. In this migration process known as chemotaxis, neutrophils reach the desired site and recognize, adhere to, and phagocytose pathogens. During phagocytosis, the pathogen is internalized within the phagocyte. The neutrophil releases its granular contents which lead to destruction of the engulfed pathogen.

Answer a is incorrect. Lymphocytes are not part of the granulocyte cells; they are key cells for the adaptive immune system and consist of B lymphocytes (humoral) and T lymphocytes (cell-mediated). T lymphocytes are tailored to defend against infections that are intracellular (viral infections), whereas B lymphocytes secrete antibodies that neutralize pathogens prior to their entry into host cells.

Answer c is incorrect. Monocytes account for 1% to 10% of circulating granulocytes and leukocytes, remove dead/damaged tissues, destroy cancer cells, and regulate against foreign substances.

Answer d is incorrect. Eosinophils account for less than 7% of circulating granulocytes and leukocytes and are present in the intestinal mucosa and lungs, two locations where foreign proteins enter the body. Eosinophils can phagocytize, kill, and digest bacteria and yeast. Elevations of eosinophil counts are highly suggestive of parasitic infections, or may be associated with allergies and asthma.

Answer e is incorrect. Basophils are the least common granulocyte, accounting for 0.1% to 0.3% of granulocytes. Signs and symptoms of allergic responses are linked to basophil and ...

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