Question 1

Parafollicular cells&#10;A) Are found in the parathyroid glands&#10;B) Are found in the zona glomerulosa&#10;C) Constitute the pars tuberalis&#10;D) Secrete a hormone that lowers blood calcium levels&#10;E) Secrete hormones responsible for establishing the basal metabolic rate

Accepted Answer

Parafollicular cells, also known as C cells, are found in the thyroid gland and secrete calcitonin, a hormone that lowers blood calcium levels.

Question 2

The trophic hormone that controls the release of T4 (thyroxine) and T3 (triiodothyronine) is secreted by&#10;A) Acidophilic cells&#10;B) Basophilic cells&#10;C) Chromaffin cells&#10;D) Chromophobic cells&#10;E) Follicular cells

Accepted Answer

Basophilic cells in the anterior pituitary gland secrete Thyroid Stimulating Hormone (TSH), which controls the release of T4 and T3 from the thyroid gland.

Question 3

Parathyroid hormone&#10;A) Decreases blood calcium levels&#10;B) Inhibits calcium resorption in the uriniferous tubules&#10;C) Is released by parafollicular cells&#10;D) Is secreted and synthesized by chief cells&#10;E) Release is stimulated by an increase in serum calcium levels

Accepted Answer

Parathyroid hormone is secreted and synthesized by chief cells in the parathyroid glands.

Answer: E
 The release of parathyroid hormone is stimulated by an increase in serum calcium levels, as the hormone acts to increase blood calcium levels.

Option A is incorrect as parathyroid hormone increases blood calcium levels, not decreases them. Option B is incorrect as parathyroid hormone stimulates calcium resorption in the uriniferous tubules, not inhibits it. Option C is incorrect as parafollicular cells secrete calcitonin, not parathyroid hormone.

Question 4

What happens immediately after insulin binds to the &#945;-subunit of the insulin receptor?&#10;A) It activates the adjacent tyrosine kinase (&#946;-subunit)&#10;B) It increases glucose uptake by the cell&#10;C) It stimulates glucagon secretion by the &#945; cells&#10;D) It stimulates the synthesis of GLUT-4 (glucose transporter-4)&#10;E) It transports the GLUT-4 protein to the cell membrane

Accepted Answer

Insulin binding to the α-subunit of the insulin receptor causes a conformational change that activates the adjacent tyrosine kinase (β-subunit). This leads to autophosphorylation of the receptor and activation of downstream signaling pathways that ultimately result in increased glucose uptake by the cell. Thus, choice B is also partially correct, but the immediate event after insulin binding is the activation of the tyrosine kinase. Choices C, D, and E are not directly related to the immediate event after insulin binding to the α-subunit.

Question 5

Which endocrine structure secretes epinephrine and norepinephrine?&#10;A) Adenohypophysis&#10;B) Adrenal cortex&#10;C) Adrenal medulla&#10;D) Neurohypophysis&#10;E) Thyroid gland

Accepted Answer

The adrenal medulla secretes epinephrine and norepinephrine, which are both hormones involved in the "fight or flight" response to stress. The adenohypophysis secretes tropic hormones that regulate various other endocrine glands, the adrenal cortex secretes steroid hormones such as cortisol, and the thyroid gland secretes thyroid hormones that regulate metabolism. The neurohypophysis stores and releases hormones produced by the hypothalamus.

Question 6

Adequate iodide levels are required for the synthesis of&#10;A) Aldosterone&#10;B) Cortisol&#10;C) Thyroid-stimulating hormone&#10;D) Thyrotropin-releasing hormone&#10;E) Thyroxine

Accepted Answer

Adequate iodide levels are required for the synthesis of thyroxine (also known as T4), a thyroid hormone produced by the thyroid gland. Iodide is incorporated into thyroxine during its synthesis, and without sufficient iodide, the thyroid gland cannot produce enough thyroxine. The other options listed, aldosterone, cortisol, thyroid-stimulating hormone, and thyrotropin-releasing hormone, are not directly related to iodide levels or the synthesis of thyroxine.

Question 7

The zona reticularis of the adrenal cortex produces&#10;A) Androgens&#10;B) Corticoids&#10;C) Glucocorticoids&#10;D) Mineralocorticoids&#10;E) Steroids

Accepted Answer

The zona reticularis of the adrenal cortex produces androgens, such as testosterone and dehydroepiandrosterone (DHEA).

Question 8

Sodium and water retention in the kidney is stimulated by a hormone secreted by&#10;A) Chromaffin cells&#10;B) Islets of Langerhans&#10;C) Zona fasciculata&#10;D) Zona glomerulosa&#10;E) Zona reticularis

Accepted Answer

The hormone that stimulates sodium and water retention in the kidney is called aldosterone, which is secreted by the adrenal gland in the zona glomerulosa. Therefore, the best answer choice is D. Chromaffin cells secrete adrenaline and noradrenaline, Islets of Langerhans secrete insulin and glucagon, Zona fasciculata secretes cortisol, and Zona reticularis secretes androgens. None of these hormones are directly involved in regulating sodium and water retention in the kidney.

Question 9

Which of the following hormones is most likely to bind to a receptor inside the cell as opposed to a membrane receptor?&#10;A) Aldosterone&#10;B) Epinephrine&#10;C) Melatonin&#10;D) Parathyroid hormone&#10;E) Vasopressin

Accepted Answer

Aldosterone is a steroid hormone which can easily cross the cell membrane and bind to intracellular receptors, whereas epinephrine, melatonin, parathyroid hormone, and vasopressin are all peptide hormones that bind to membrane receptors.

Deck 19: Endocrine System