What is the role of the helper T-cells in cell-mediated immunity?
Produce chemicals that regulate the level of the immune response.
Recognize foreign antigens and initiate an immune response
Chemically destroy foreign antigens by disrupting cell membranes.
Create antibodies to target foreign antigens.
The Correct Answer is B
a. Produce chemicals that regulate the level of the immune response: While some T-cells can secrete cytokines that regulate the immune response, this is not the primary function of helper T-cells.
b. Recognize foreign antigens and initiate an immune response. Helper T-cells (Th cells) are a type of lymphocyte crucial in cell-mediated immunity. They play a central role in recognizing and identifying foreign antigens (substances recognized as foreign by the immune system). Once they recognize an antigen, they activate other immune cells like cytotoxic T cells and B cells to mount an immune response.
c. Chemically destroy foreign antigens by disrupting cell membranes: This is the function of cytotoxic T cells, not helper T-cells.
d. Create antibodies to target foreign antigens: Antibody production is the function of B cells activated by helper T-cells.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
a. AB positive: Individuals with AB positive blood are universal recipients. They have A and B antigens on their red blood cells but no antibodies (anti-A or anti-B) in their plasma. Therefore, their body will not reject blood types A, B, AB, or Rh positive or negative.
b. A positive: Individuals with A positive blood can only receive A positive or O positive blood. Their plasma contains anti-B antibodies, which would attack blood types B and AB.
c. B negative: Individuals with B negative blood can receive B negative or O negative blood. Their plasma contains anti-A antibodies, which would attack blood types A and AB. The Rh factor is another compatibility consideration, but the question specifies positive.
d. O negative: Individuals with O negative blood are universal donors but not universal recipients. Their red blood cells lack A and B antigens, so they can be donated to anyone. However, their plasma contains anti-A and anti-B antibodies, so they can only receive O negative blood.
Correct Answer is D
Explanation
a. Activation of plasmin: Plasmin is involved in breaking down blood clots, not in their formation. It is part of the fibrinolytic system.
b. Activation of heparin: Heparin is an anticoagulant that prevents clotting; it is not required for blood clotting.
c. Adequate levels of potassium: Potassium is important for cellular function but does not play a direct role in blood clotting.
d. Adequate levels of calcium: Calcium ions are essential for various steps in the blood clotting cascade, including the activation of certain clotting factors.
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