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Unformatted text preview: Parathyroid
hormone will increase the number of osteoclasts, which break down bone cells. Therefore,
one would expect an increase in both parathyroid hormone and osteoclast activity in order to
increase the level of calcium in the blood plasma. However, vitamin C promotes bone
formation, a process that would further lower the calcium level in the plasma.
6. D. Removal of the parathyroid gland would lead to hypocalcemia, a condition of low blood
calcium, resulting from the lack of parathyroid hormone. This would cause increased
neuromuscular excitability because of the change in membrane potential, which under
normal physiological conditions, is partially kept in balance with extracellular calcium.
Typically, the person would eventually die from severe respiratory muscle spasms.
7. A. As early humans migrated from Africa to Europe they experienced decreased exposure to
sunlight. This necessitated an increase in calcium intake (in this case from dairy products)
and a decrease in melanin in the skin to increase the rate of vitamin D production from
8. C. Scurvy is caused by a deficiency in vitamin C. Vitamin C acts in the formation and
maintenance of connective tissue. Bleeding under the skin, fluctuating blood pressure and
heart rate, and brittle bones would all be expected consequences of weak connective tissues. Page 1 of 12 A tingling sensation in the limbs is the result of a neural impairment, not a connective tissue
9. D. All of these are functions of the vertebrate skeleton except detoxification of poisons which
is mostly the responsibility of the liver.
10. A. Control of heart rate, muscle coordination, and appetite is maintained by the brain stem,
cerebellum, and hypothalamus, respectively.
11. C. According to the item, Norman noticed that his skin blood vessels were usually
constricted to conserve body heat in the cold environment of the mountains where he went
skiing. Occasionally, however, his vessels would dilate for short periods of time to enable a
sufficient supply of blood (and oxygen) to his cells. D...
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- Spring '11