Select the best answer or answers from the choices given: Parathyroid hormone (a) increases bone formation and lowers blood calcium levels, (b) increases calcium excretion from the body, (c) decreases calcium absorption from the gut, (d) demineralizes bone and raises blood calcium levels.
Select the best answer or answers from the choices given: Parathyroid hormone (a) increases bone formation and lowers blood calcium levels, (b) increases calcium excretion from the body, (c) decreases calcium absorption from the gut, (d) demineralizes bone and raises blood calcium levels.
Parathyroid hormone (PTH), also called parathormone, is a hormone secreted by the parathyroid gland that regulates the serum calcium concentration through its effects on bone, kidney, and intestine.
PTH influences bone remodeling, which is an ongoing process in which bone tissue is alternately rebuilt over time. PTH is secreted in response to low blood serum Ca2+ levels. PTH indirectly stimulates osteoclast activity within the bone matrix , in an effort to release more ionic calcium (Ca2+) into the blood to elevate a low serum calcium level. The bones act as a (metaphorical) "bank of calcium" from which the body can make "withdrawals" as needed to keep the calcium amount in the blood at appropriate levels despite the ever-present challenges of metabolism, stress, and nutrient variations. PTH is "a key that unlocks the bank vault" to remove the calcium.
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