A red blood cell contains a large nucleus; it is thicker near the center and thin around the rim of the cell:
False
True.
The Correct Answer is A
Red blood cells do not contain a large nucleus; in fact, they do not contain a nucleus at all when they are mature.
This is an adaptation that allows them to carry more hemoglobin, the protein that binds oxygen, and to squeeze through narrow capillaries.
Choice B is wrong because it contradicts the fact that red blood cells are enucleated (lacking a nucleus) in humans and most mammals.
Some vertebrates, such as birds and fish, have nucleated red blood cells, but they are not thick near the center and thin around the rim of the cell.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
The correct answer is choice B. True.
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.
Choice A is wrong because it is the opposite of the correct answer.
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.
Correct Answer is B
Explanation
The hypothalamus is the part of the brain that produces hormones that control the pituitary gland.
The pituitary gland then releases hormones that target other endocrine glands, such as the thyroid, adrenal, and gonads.
Therefore, the hypothalamus is the source of releasing hormones for target cells in the anterior pituitary gland.
Choice A is wrong because the anterior pituitary gland does not produce releasing hormones, but responds to them by secreting other hormones.
Choice C is wrong because the thyroid gland does not produce releasing hormones, but responds to them by secreting thyroid hormones.
Choice D is wrong because the posterior pituitary gland does not produce releasing hormones, but stores and releases hormones made by the hypothalamus, such as oxytocin and antidiuretic hormone.
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