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
The pulmonary circuit sends oxygen-poor blood to the lungs, where it is oxygenated and returned to the heart.
This is distinguished from the systemic circuit, which sends oxygen-rich blood to the tissues and returns oxygen-poor blood to the heart.
Choice A is wrong because it confuses the pulmonary circuit with the systemic circuit. The pulmonary circuit does not send blood to the tissues but to the lungs.
Choice B is wrong because it only describes part of the pulmonary circuit.
The pulmonary circuit sends oxygen-poor blood to the heart, but only after it has been oxygenated in the lungs.
Choice C is wrong because it confuses the pulmonary circuit with the systemic circuit. The pulmonary circuit does not bring blood from the tissues but from the heart.
Correct Answer is A
Explanation
The right atrium receives blood directly from the superior vena cava, inferior vena cava, and coronary sinus.
The superior vena cava and inferior vena cava bring deoxygenated blood from the upper and lower body, respectively.
The coronary sinus brings blood from the heart muscle.
Choice B is wrong because it excludes the coronary sinus, which also empties into the right atrium.
Choice C is wrong because it includes the pulmonary veins, which carry oxygenated blood from the lungs to the left atrium, not the right atrium.
Choice D is wrong because it only includes the pulmonary veins, which are not connected to the right atrium at all.
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