DPT 6150 Endocrine Practice Quiz

In controlling aldosterone secretion, angiotensin II acts on which structure? A) Zona glomerulosa B) Zona fasiculata C) Zona reticularis D) Adrenal medulla

A) The cells of the zona glomerulosa secrete most of the aldosterone. These cells have receptors for angiotensin II, which is a major controller of aldosterone secretion.

Which of the following statements about peptide or protein hormones is usually true? A) They have longer half lives than steroid hormones. B) They have receptors on the cell membrane. C) They have a slower onset of action than both steroid and thyroid hormones. D) They are not stored in endocrine-producing glands.

B) In general, peptide hormones produce biological effects by binding to receptors on the cell membrane. They are stored in secretion granules in their endocrine-producing cells and have relatively short half-lives because they are not highly bound to plasma proteins. Protein hormones often have rapid onset of action because, unlike steroid and thyroid hormones, protein synthesis is usually not a prerequisite to produce biological effects.

Inhibition of the iodide pump would be expected to cause which of the following changes? A) Increased synthesis of thyroxine (T4) B) Increased synthesis of thyroglobulin C) Increased metabolic rate D) Decreased thyroid-stimulating hormone secretion E) Extreme nervousness

B) Inhibition of the iodide pump decreases the synthesis of thyroid hormones but does not impair the production of thyroglobulin by follicular cells. Decreased plasma levels of thyroid hormones result in a low metabolic rate and lead to an increase in thyroid-stimulating hormone (TSH) secretion. Increased plasma levels of TSH stimulate the follicular cells to synthesize more thyroglobulin. Nervousness is a symptom of hyperthyroidism and is not caused by thyroid hormone deficiency.

Which of the following would most likely occur in the earliest stages of type II diabetes? A) Increased insulin sensitivity B) High circulating levels of C-peptide C) Decreased hepatic glucose output D) Metabolic acidosis E) Hypovolemia

B) The early stages of type II are associated with diminished sensitivity of target tissues to the metabolic effects of insulin, a condition referred to as insulin resistance. Decreased insulin sensitivity tends to increase plasma glucose concentration, in part by promoting hepatic release of glucose. Increased plasma glucose concentration leads to a compensatory increase in the secretion of insulin and C-peptide, which is a cleavage product of proinsulin. Metabolic acidosis and hypovolemia occur in type I diabetes but are not present in the early stages of type II diabetes.

A 40-year old woman comes to the emergency room with a fracture in the neck of the femur. Radiographs reveal generalized demineralization of the bone in the area. Her plasma calcium ion concentration is significantly greater than normal (12.2 mg/dL). Which of the following conditions is consistent wit this presentation? A) Osteoporosis B) Rickets C) Hyperparathyroidism D) Renal failure

C) Demineralization of the bone could be caused by any of the choices, but only an elevated parathyroid hormone concentration would result in both demineralization and elevated plasma calcium concentration.

Which of the following findings is most likely to occur in a patient who has uncontrolled type 1 diabetes mellitus? A) Decreased plasma osmolality B) Increased plasma volume C) Increased plasma pH D) Increased release of glucose from the liver E) Decrease rate of lipolysis

D) Because insulin secretion is deficient in type 1 diabetes mellitus, there is increased release of glucose from the liver. Low plasma levels of insulin also lead to a high rate of lipolysis, increased plasma osmolality, hypovolemia, and acidosis are all symptoms of uncontrolled type 1 diabetes mellitus.

Which of the following findings would likely be reported in a patient with a deficiency in iodine intake? A) Weight loss B) Nervousness C) Increased sweating D) Increased synthesis of thyroglobulin E) Tachycardia

D) Because iodine is needed to synthesize thyroid hormones, the production of thyroid hormones is impaired if iodine is deficient. As a result of feedback, plasma levels of thyroid-stimulating hormone increase and stimulate the follicler cells to increase synthesis of thyroglobulin. This results in a goiter. Increased metabolic rate, sweating, nervousness, and tachycardia are all common features of hyperthyroidism, not hypothyroidism due to iodine deficiency.

Seven days after ovulation, pituitary secretion of luteinizing hormone (LH) decreases rapidly. What is the cause of this decrease in secretion? A) Anterior pituitary gland becomes unresponsive to the stimulatory effect of gonadotropin-releasing hormone (GnRH) B) Estrogen from the develop follicles exerts a feedback inhibition on the hypothalamus. C) The rise in body temperature inhibits hypothalamic release of GnRH. D) Secretion of estrogen and progesterone by the corpus luteum suppresses hypothalamic secretion of GnRH and pituitary secretion of LH. E) None of the above.

D) Estrogen and progesterone are formed in large amounts by the mature corpus luteum that has formed by 7 days following ovulation, causing negative feedback inhibition of LH secretion from the anterior pituitary.

A 46-year old man has "puffy" skin and is lethargic. His plasma thyroid stimulating hormone concentration is low and increases markedly when he is given thyrotropin-releasing hormone. Which of the following is the most likely diagnosis? A) Hyperthyrodisim due to thyroid tumor. B) Hyperthyroidism due to abnormality in hypothalamus. C) Hypothyroidism due to abnormality in thyroid. D) Hypothyroidism due to abnormality in hypothalamus. E) Hypothyroidism due to abnormality in pituitary.

D) Lethargy and myxedema are signs of hypothyroidism. Low plasma levels of thyroid-stimulating hormone indicate that the abnormality is in either the hypothalamus or the pituitary gland. Because the pituitary gland was responsive to the administration of TRH, this suggest the pituitary is functioning normally, and the hypothalamus is producing insufficient TRH.

Some cells secrete chemicals into the extracellular fluid that act on cells in the same tissue. Which of the following refers to this type of regulation? A) Neural B) Endocrine C) Neuroendocrine D) Paracrine E) Autocrine

D) Paracrine communication refers to cell secretions that diffuse into the extracellular fluid to affect neighboring cells.

A 40-year old man is sodium-depleted is adminstered an angiotensin converting enzyme (ACE) inhibitor for 2 weeks. Which set of physiological changes would most likely occur in this patient? A) No change to plasma aldosterone concentration, plasma cortisol concentration or sodium excretion. B) No change to plasma aldosterone concentration or sodium secretion, but decreased plasma cortisol concentration. C) Decreased plasma aldosterone concentration, no change to plasma cortisol concentration, and increased sodium excretion. D) Decreased plasma aldosterone and cortisol concentrations with increased sodium excretion. E) Decreased plasma aldosterone concentration with no change to either plasma cortisol concentration or sodium excretion.

E) During sodium depletion, the renin-angiotensin system is activated, and high levels of circulating angiotensin II stimulate the adrenal glands to secrete increased amounts of aldosterone. Angiotensin II has no effect on cortisol secretion, and sodium depletion is associated with normal levels of cortisol. Consequently, reducing plasma levels of angiotensin II by administering an ACE inhibitor would decrease plasma aldosterone to normal levels but would have no effect on plasma cortisol concentration. Because high plasma levels of aldosterone promote sodium retention, reducing aldosterone levels by administering an ACE inhibitor would tend to produce a natriuresis and a decrease in arterial pressure. In time, the opposing effects of reduced arterial pressure and aldosterone secretion on sodium excretion would offset each other, and sodium balance would eventually be achieved at a lower arterial pressure.

Which of the following is inconsistent with the diagnosis of Graves' disease? A) Increased HR B) Exophthalmos C) Increased plasma T3 D) Increased plasma T4 E) Increased plasma levels of thyroid-stimulating hormone.

E) In Graves' diseases, thyroid stimulating immunoglobulins bind to cell membrane receptors, causing the thyroid to produce excess T3 and T4. As a result of negative feedback, increased plasma levels of T3 and T4 suppress the thyroid stimulating hormone.In addition, plasma levels of immunoglobulins often cause exophthalamos, and an increased HR is common in response to the high circulating levels of thyroid hormones.

Growth hormone secretion would most likely be suppressed under which of the following conditions? A) Acromegaly B) Gigantism C) Deep sleep D) Exercise E) Acute hyperglycemia

E) Under acute conditions, an increase in blood glucose concentrations will decrease growth hormone secretion. GH secretion is elevated in chronic pathophysiological states of acromegaly and gigantism. Deep sleep and exercise are stimuli that increase GH secretion.