Complement proteins and antibodies coat a microorganism and provide binding sites, enabling macrophages and neutrophils to phagocytize the organism. This phenomenon is termed
opsonization
agglutination
chemotaxis
diapedesis
The Correct Answer is A
A. Opsonization: Opsonization is the process by which antibodies and complement proteins coat a pathogen, enhancing recognition and binding by phagocytes. This coating increases the efficiency of phagocytosis and helps eliminate the microorganism.
B. Agglutination: Agglutination occurs when antibodies bind multiple antigens together, causing clumping of pathogens. While it helps contain infections, it does not directly facilitate phagocytosis in the same way opsonization does.
C. Chemotaxis: Chemotaxis refers to the directed movement of immune cells toward a site of infection or tissue damage, guided by chemical signals. It does not involve coating pathogens for phagocytosis.
D. Diapedesis: Diapedesis is the process by which leukocytes squeeze through capillary walls to reach infected tissues. It facilitates immune cell migration but is not the mechanism by which pathogens are marked for phagocytosis.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
A. IgE:IgE is primarily involved in allergic reactions and defense against parasitic infections. It is present in very low concentrations in plasma compared to other antibody classes.
B. IgM:IgM is the first antibody produced during a primary immune response. Although effective in agglutination and complement activation, it is less abundant in plasma than IgG.
C. IgG:IgG is the most abundant antibody in plasma, accounting for about 75–80% of circulating antibodies. It provides long-term immunity after infection or vaccination and can cross the placenta to provide passive immunity to the fetus.
D. IgA:IgA is mainly found in mucosal secretions such as saliva, tears, and breast milk. Its plasma concentration is lower than IgG, making it less abundant in the bloodstream.
E. IgD:IgD is present in very low concentrations in plasma and primarily functions as a receptor on immature B cells rather than providing systemic immunity.
Correct Answer is B
Explanation
A. T cells:T lymphocytes are part of the adaptive immune system and require specific antigen recognition for activation. They provide targeted responses and immunological memory but do not act immediately. Their function is delayed compared to innate immune cells, so they are not a component of innate defenses.
B. Natural killer cells:Natural killer (NK) cells are innate immune cells that act without prior sensitization. They can recognize and destroy virus-infected or abnormal cells immediately. This rapid, non-specific action provides a critical first line of defense against infections and tumor cells.
C. Plasma cells:Plasma cells are differentiated B cells that secrete antibodies as part of the adaptive immune response. They take several days to develop after antigen exposure and are not involved in immediate, non-specific innate defense mechanisms.
D. B cells:B lymphocytes belong to the adaptive immune system and require activation by antigens and helper T cells to produce antibodies. Their responses are specific and delayed, unlike innate immune cells that respond immediately to threats.
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