As a result of the allergen-antibody reaction, mast cells release histamine:
False
True
The Correct Answer is B
As a result of the allergen-antibody reaction, mast cells release histamine.
This is because when mast cells are exposed to an allergen that binds to IgE antibodies attached to their FcɛRI receptors, they release histamine and other inflammatory mediators.
Histamine causes vasodilation, increased capillary permeability, mucus secretion, and smooth muscle contraction, which result in allergic symptoms such as itching, swelling, sneezing, and wheezing.
Mast cells do release histamine in response to allergen-antibody reactions. Some additional sentences are:
Normal ranges of histamine levels vary depending on the tissue and the method of measurement, but they are usually low in healthy individuals and elevated in allergic conditions.
Histamine can be degraded by enzymes such as diamine oxidase and histamine N- methyltransferase, or inhibited by drugs such as antihistamines.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Atrial natriuretic peptide (ANP) is a hormone secreted by the heart when the atria are stretched by high blood pressure or volume.
ANP has multiple effects, such as increasing urine and salt excretion, lowering blood pressure, and opposing the renin-angiotensin-aldosterone system.
Therefore, ANP inhibits the release of renin and aldosterone, which are hormones that increase blood pressure and sodium retention.
Choice A is wrong because ANP is not released from the adrenal cortex but from the cardiac atria.
ANP does not stimulate atrial hormones but rather inhibits them.
Choice B is wrong because ANP is not stimulated to release when blood volume decreases, but when it increases.
ANP acts to reduce blood volume by promoting diuresis and natriuresis.
Choice C is wrong because ANP does not raise blood pressure, but lowers it. ANP acts as a vasodilator and reduces peripheral resistance.
Correct Answer is A
Explanation
It is a major component of the lymphatic system and contains T and B lymphocytes.
Choice B is wrong because the spleen does not produce T lymphocytes, but rather stores them.
T lymphocytes are produced in the thymus.
Choice C is wrong because the spleen does not filter lymph, but rather blood. It traps bloodborne microbes and produces an immune response to them.
Choice D is wrong because the spleen consists of one lobe and is located in the upper left abdomen below the diaphragm.
The description in choice D matches the thymus, not the spleen.
The normal size of the spleen in adults is about 12 cm long, 8 cm broad, and 3-4 cm thick, weighing about 200 g.
The normal range of splenic index (the product of length, width, and thickness) is 120-480 cm.
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