Question 19 [ Select ] [\"Parathyroid hormone\", \"Vitamin D3\", \"Proinsulin\"]

Question

Question 19

                           [ Select ]                       ["Parathyroid hormone", "Vitamin D3", "Proinsulin"]         is the most important hormone controlling the calcium concentrations in blood. It causes                            [ Select ]                       ["a decrease", "an increase"]         in blood calcium, which through feedback decreases its release from the                            [ Select ]                       ["hypothalamus", "parathyroid", "thyroid"]         .

Question 20

Exposure of the uterus to                            [ Select ]                       ["testosterone", "T3", "estrogen"]         enhances its responsiveness to progesterone, and this enhancement by the first hormone is best described as a                           [ Select ]                       ["permissive", "negative feedback loop", "restrictive"]         effect on the action of progesterone.

Question 21

The enzyme phospholipase C is activated after binding of epinephrine to                           [ Select ]                       ["a gamma", "a beta", "an alpha"]         -adrenergic receptor, leading to production of                           [ Select ]                       ["cAMP", "IP3", "DAG"]         which binds to a receptor on the                           [ Select ]                       ["plasma membrane", "mitochondria", "endoplasmic reticulum"]         and results in a transient rise in cytoplasmic                           [ Select ]                       ["calcium", "magnesium", "manganese"]         ions.

Question 22

The pituitary gland is attached to the                            [ Select ]                       ["hypothalamus", "medulla oblongata", "spinal cord"]         and releases the hormone                           [ Select ]                       ["estrogen", "T4", "prolactin", "testosterone"]         as well as                            [ Select ]                       ["acetylcholine", "T3", "growth hormone"]         and                           [ Select ]                       ["ACTH", "Proinsulin"]         .

Question 23

An increase in hormone concentrations in the blood can lead to an upregulation of                           [ Select ]                       ["hormone production", "receptor numbers"]         in the target tissue, leading to                            [ Select ]                       ["decreased", "increased"]       sensitivity to the hormone.

Explanation / Answer

Q 19)

hormones for maintaining calcium levels in the body are parathyroid hormone (PTH)and 1,25(OH)2D (the active form of vitamin D). The major regulator is PTH, which is part of a negative feedback loop to maintain [Ca++]ECF . PTH secretion is stimulated by hypocalcemia, and it works through three mechanisms to increase Ca++ levels:

PTH indirectly stimulates Ca++ absorption in the small intestine by stimulating synthesis of 1,25(OH)2D in the kidney.

So,

Parathyroid hormone is the most important hormone controlling the calcium concentrations in blood . It causes increase in blood calcium which through feedback decreases its release from parathyroid

Q 20) Exposure of the uterus to testosterone enhances its responsiveness to progesterone , and this enhancement by the first hormone is best described as negative feedback effect on the action of progesterone.

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