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.
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Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
Positive feedback mechanisms move conditions away from the normal state.
They amplify the original action and produce more of the same effect.
For example, blood clotting and childbirth are positive feedback mechanisms.
Choice A is wrong because positive feedback mechanisms usually produce unstable conditions.
They do not resist change but rather enhance it.
Choice B is wrong because positive feedback mechanisms do not cause long-term changes.
They are ultimately stopped by negative feedback loops once the process they were used for is complete.
Choice D is wrong because positive feedback mechanisms do not bring conditions back to the normal state.
That is the role of negative feedback mechanisms, which oppose the stimulus and restore homeostasis.
Correct Answer is B
Explanation
Kidney disease can cause hypertension by activating the renin-angiotensin mechanism.
This mechanism involves the release of renin from the kidneys, which stimulates the production of angiotensin II, a hormone that constricts blood vessels and increases blood pressure.
Choice A is wrong because kidney disease does not directly signal the brain stem to increase blood pressure.
The brain stem regulates blood pressure through the autonomic nervous system, which responds to various stimuli such as stress, pain, or emotions.
Choice C is wrong because kidney disease does not increase the release (excretion) of sodium and water.
On the contrary, kidney disease can impair the ability of the kidneys to filter out excess sodium and water, which can lead to fluid retention and increased blood pressure.
Choice D is wrong because kidney disease does not stimulate the secretion of ANP.
ANP stands for atrial natriuretic peptide, a hormone that is secreted by the heart when it senses high blood pressure.
ANP causes the kidneys to excrete more sodium and water, which lowers blood pressure.
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