11. ADH is: a. produced in the posterior pituitary b. a neural hormone c. carrie
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Question
11. ADH is:
a. produced in the posterior pituitary
b. a neural hormone
c. carried in the blood bound to the protein neurophysin
d. a large protein that must be administered by injection
e. all of the above
12. Actions of ADH include:
a. stimulation of ACTH synthesis and secretion
b. inhibition of renal cAMP production
c. antagonism of the actions of oxytocin
d. inhibition of the sensation of thirst
e. b and c
13. A patient has an ADH-secreting pulmonary carcinoma (syndrome of inappropriate ADH secretion). As a result of unregulated ADH secretion, you would expect to find:
a. retention of water resulting in volume expansion
b. low urinary osmolality
c. increased renal sodium reabsorption
d. high serum sodium concentration
e. b and c
14. A 25-year old woman develops a nonfunctional hypothalamic tumor that results in a complete inability to produce oxytocin. The most likely pathological response to this deficiency is:
a. inability to ovulate
b. amenorrhea
c. hypertension
d. inability to lactate normally
e. inability to deliver a child vaginally
15. Secretion of PTH is increased by:
a. an increase in serum magnesium concentration
b. an increase in serum phosphate concentration
c. an increase in dietary calcium
d. a decrease in dietary calcium
e. treatment with thiazide diuretics
16. Hyperparathyroidism results in:
a. alkalosis
b. hypercalcemia
c. hyperphosphatemia
d. hypophosphaturia
e. hypocalcemia
17. A 50-year-old man has low serum calcium and high serum phosphate levels. His urinary cAMP levels are low. He most likely suffers from:
a. Hypoparathyroidism
b. Hyperparathyroidism
c. Vitamin D deficiency
d. Cushing’s syndrome
18. Bone loss associated with renal failure occurs because:
a. the failing kidney is no longer capable of PTH production
b. renal phosphate clearance decreases in renal failure
c. the failing kidney increases activation of vitamin D
d. renal calcium clearance increases in renal failure
19. Which set of serum values would be most typical of a patient with a vitamin D deficiency?
a. high serum phosphate, high serum calcium, and high PTH
b. low serum phosphate, high serum calcium, and high PTH
c. low serum phosphate, high serum calcium, and low PTH
d. low serum phosphate, low serum calcium, and high PTH
e. high serum phosphate, low serum calcium, and low PTH
20. Which cause-and-effect relationship is correct for a deficiency of active vitamin D (calcitriol)?
a. bone formation is increased because vitamin D blocks the action of PTH on bone resorption
b. osteoporosis, but not osteomalacia, is associated with a calcitriol deficiency because calcitriol synergizes with PTH in its action on bone
c. hypophosphatemia occurs because of decreased intestinal phosphate absorption
d. hypercalcemia occurs because of decreased intestinal calcium absorption
Explanation / Answer
11) Option e is correct; ADH (Anti-Diuretic hormone) is a nine amino acid peptide secreted from the posterior pituitary. Within hypothalamic neurons, the hormone is packaged in secretory vesicles with a carrier protein called neurophysin, and both are released upon hormone secretion.
12) Options a and d are correct; In the anterior lobe of the pituitary gland, CRH and ADH stimulate synthesis and secretion of ACTH. Also, ADH is an anti-diuretic hormone, i.e., its action is to conserve body water by reducing the loss of water in urine. Thus, it inhibits the sensation of thirst.
13) Option e is correct; Excessive ADH causes an inappropriate increase in the reabsorption in the kidneys of solute-free water ("free water"): excess water moves from the distal convoluted tubules (DCT)s and collecting tubules of the nephrons - via activation of aquaporins, the site of the ADH receptors - back into the circulation. This has two consequences. First, in the extracellular fluid (ECF) space, there is a dilution of blood solutes, causing hypoosmolality, including a low sodium concentration - hyponatremia. There is no expansion of the ECF volume because as it attempts to expand, aldosterone is suppressed and atrial natriuretic peptide (ANP) is stimulated: both of these hormones cause isotonic ECF fluid to be excreted by the kidneys sufficient to keep ECF volume at a normal level.
14) Option d is correct; Oxytocin promotes lactation by moving the milk into the breast. When the baby sucks at the mother's breast, oxytocin secretion causes the milk to release so the baby can feed. It also induces contractions in uterine wall during parturition, however synthetic oxytocin (pitocin) can be used to induce a woman to start labor if she cannot start naturally
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