T lymphocytes are responsible for:
Humoral immunity.
Cell-mediated immunity.
Programming macrophages.
Producing antibodies.
The Correct Answer is B
T lymphocytes, also known as T cells, are a type of white blood cell that is an essential part of the immune system.
T cells are one of two primary types of lymphocytes — B cells being the second type — that determine the specificity of immune response to antigens (foreign substances) in the body.
T cells can be distinguished from other lymphocytes by the presence of a T-cell receptor (TCR) on their cell surface.
T cells originate in the bone marrow and mature in the thymus.
After migration to the thymus, the precursor cells mature into several distinct types of T cells.
One of these types is the CD8+ T cell, also known as cytotoxic T cell, which is responsible for cell-mediated immunity.
Cell-mediated immunity is the type of immunity that involves the direct killing of infected cells and cancer cells by cytotoxic T cells.
Choice A is wrong because humoral immunity is the type of immunity that involves the production of antibodies by B cells and plasma cells.
Antibodies are proteins that bind to specific antigens and mark them for destruction by other immune cells.
Choice C is wrong because programming macrophages is not a function of T lymphocytes.
Macrophages are a type of phagocytic cell that can engulf and digest pathogens and cellular debris.
Macrophages can be activated by cytokines, which are chemical messengers secreted by helper T cells and other immune cells.
Choice D is wrong because producing antibodies is not a function of T lymphocytes.
As mentioned above, antibodies are produced by B cells and plasma cells, which are another type of lymphocyte.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
The radial artery is one of the major blood-supplying vessels to the forearm and hand.
It can be felt as a pulse near the thumb on the wrist by gently pressing the artery against the underlying bone.
This is the most commonly measured pulse by nurses to assess peripheral pulse characteristics.
Choice B.
Palmar arch arteries are wrong because these are branches of the radial and ulnar arteries that form anastomosis in the palm of the hand.
They are not palpable on the wrist.
Choice C.
The brachial artery is wrong because this is the main artery of the upper arm that bifurcates into the radial and ulnar arteries at the cubital fossa.
It can be felt as a pulse in the antecubital fossa, not near the thumb on the wrist.
Choice D
The Ulnar artery is wrong because this is another major blood-supplying vessel to the forearm and hand that runs along the medial aspect of the forearm.
It can be felt as a pulse on the little finger side of the wrist, not near the thumb.
Correct Answer is C
Explanation
The conversion of fibrinogen to fibrin by thrombin is the final step in the formation of a blood clot.
Fibrin is a protein that forms a net-like structure that traps platelets and other blood cells, making the clot stronger and more durable.
Choice A is wrong because the formation of a prothrombin activator is the first step in the formation of a blood clot.
A prothrombin activator is a complex of enzymes that converts prothrombin to thrombin.
Choice B is wrong because the conversion of prothrombin to thrombin by the prothrombin activator is the second step in the formation of a blood clot.
Thrombin is an enzyme that converts fibrinogen to fibrin.
Choice D is wrong because tissue damage is not a step in the formation of a blood clot, but a trigger for the clotting process.
When blood vessels are injured, they release substances that activate platelets and clotting factors.
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