Endocrine-Parathyroid: Cellular Biology & Homeostasis
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Questions and Answers

Where are the parathyroid glands usually located in most species?

  • Within the liver
  • Near the kidneys
  • On the lobes of the thyroid glands (correct)
  • Attached to the spinal cord

What is the function of a preprohormone in hormone synthesis?

  • Stored in secretory granules after cleavage
  • Immediate release into the bloodstream
  • Active form in the Golgi apparatus
  • Inactive molecule in the endoplasmic reticulum (correct)

Which cells are responsible for synthesizing parathyroid hormone (PTH)?

  • Osteoclasts
  • Osteocytes
  • Osteogenic cells
  • Parathyroid chief cells (correct)

In which organelle is a prohormone cleaved into its active form?

<p>Golgi apparatus (D)</p> Signup and view all the answers

What is the primary target tissue or organ affected by parathyroid hormones?

<p>Kidneys (B)</p> Signup and view all the answers

Which type of gland is the parathyroid gland classified as?

<p>Endocrine gland (A)</p> Signup and view all the answers

What is the role of calcitriol in calcium metabolism?

<p>Enhances calcium absorption in the intestines (A)</p> Signup and view all the answers

What is the primary function of Parathyroid Hormone (PTH) on target tissues?

<p>Increase calcium reabsorption in kidneys (D)</p> Signup and view all the answers

What is the primary stimulus for the release of PTH from the parathyroid gland?

<p>Decrease in blood ionized calcium levels (A)</p> Signup and view all the answers

What is the role of the oxyphil cells in the parathyroid gland?

<p>Unknown, but they are larger than the chief cells and have oxidative and hydrolytic enzyme activity (D)</p> Signup and view all the answers

How is PTH synthesized in the parathyroid gland?

<p>Prepro-PTH is synthesized in the rough endoplasmic reticulum (rER) and then cleaved to pro-PTH, which is then secreted (A)</p> Signup and view all the answers

What is the primary role of calcium and phosphate in the body?

<p>They play a major role in physiological homeostasis, including muscle contraction, nerve cell activity, and the structural integrity of bones and teeth (D)</p> Signup and view all the answers

What is the half-life of parathyroid hormone (PTH) in the body?

<p>5-10 minutes (B)</p> Signup and view all the answers

How are the calcium-sensing receptors on the parathyroid gland membrane involved in PTH regulation?

<p>They are G-protein coupled receptors that activate the cAMP-PKA pathway, which stimulates PTH release (C)</p> Signup and view all the answers

Where is PTH primarily metabolized in the body?

<p>Primarily in the liver (C)</p> Signup and view all the answers

What is the approximate percentage of calcium found in the bones?

<p>99% (B)</p> Signup and view all the answers

Which of the following is not a major function of calcium and phosphate in the body?

<p>Regulation of body temperature (B)</p> Signup and view all the answers

What is the usual number of parathyroid glands pairs found in most species?

<p>Two pairs (D)</p> Signup and view all the answers

What is the primary chemical structure of parathyroid hormone (PTH)?

<p>Protein (A)</p> Signup and view all the answers

Which organelle is responsible for cleaving a prohormone into its active hormone form?

<p>Golgi apparatus (D)</p> Signup and view all the answers

What is the usual type of molecule in which hormones are synthesized initially before being activated into hormones?

<p>Pre-prohormone (B)</p> Signup and view all the answers

What is the primary role of the calcium-sensing receptors on the parathyroid gland membrane?

<p>To detect changes in blood ionized calcium levels and regulate PTH release (A)</p> Signup and view all the answers

Which of the following statements about the synthesis of PTH is true?

<p>Prepro-PTH is synthesized in the rough endoplasmic reticulum and then cleaved to pro-PTH (D)</p> Signup and view all the answers

Which of the following is the primary stimulus for the secretion of aldosterone?

<p>Increased plasma potassium concentration (C)</p> Signup and view all the answers

Which of the following stimuli is the primary trigger for renin secretion from the juxtaglomerular apparatus?

<p>Reduced blood pressure in the kidney (B)</p> Signup and view all the answers

How does ACTH (adrenocorticotropic hormone) influence aldosterone secretion?

<p>ACTH has no significant effect on aldosterone synthesis and secretion (A)</p> Signup and view all the answers

What is the primary anatomical location of the zona glomerulosa, the site of aldosterone synthesis?

<p>The outer cortex of the adrenal gland (B)</p> Signup and view all the answers

Which of the following is a key function of the renin-angiotensin-aldosterone system (RAAS) in regulating aldosterone secretion?

<p>Detecting changes in blood pressure in the kidney (A)</p> Signup and view all the answers

How does an increase in plasma potassium concentration influence aldosterone secretion?

<p>It stimulates aldosterone secretion independently of the RAAS (B)</p> Signup and view all the answers

What is the primary target tissue for the actions of aldosterone?

<p>The distal renal tubules (B)</p> Signup and view all the answers

Which of the following is a key function of the macula densa in the regulation of aldosterone secretion?

<p>Detecting changes in plasma sodium concentration (B)</p> Signup and view all the answers

What is the primary role of the afferent arteriole baroreceptors in the regulation of aldosterone secretion?

<p>They detect changes in blood pressure in the kidney (A)</p> Signup and view all the answers

What is the primary function of the Zona Glomerulosa in the adrenal gland?

<p>Secretion of mineralocorticoids (C)</p> Signup and view all the answers

How are steroid hormones primarily transported in the blood after being synthesized?

<p>By binding to specific carrier proteins (A)</p> Signup and view all the answers

Which enzyme is mainly involved in the conversion of cholesterol to pregnenolone in steroidogenesis?

<p>ACTH (B)</p> Signup and view all the answers

In steroid hormone metabolism, what process mainly occurs in the liver to prepare them for excretion?

<p>Conjugation to sulfates and glucuronides (D)</p> Signup and view all the answers

What is the approximate clearance half-life of aldosterone in the body?

<p>20 minutes (D)</p> Signup and view all the answers

Which glandular axis regulates the synthesis of steroid hormones in the adrenal cortex?

<p>Hypothalamic-Pituitary-Adrenal (HPA) axis (D)</p> Signup and view all the answers

What is the main role of mineralocorticoids synthesized by the adrenal gland?

<p>Control of salt and water balance (C)</p> Signup and view all the answers

How do steroid hormones trigger a response in target cells?

<p>By binding to intracellular receptors and controlling gene transcription (D)</p> Signup and view all the answers

Where do Androgen hormones primarily bind in target cells to trigger a rapid cellular response?

<p>Cell membrane receptors (D)</p> Signup and view all the answers

Which layer of the adrenal gland produces glucocorticoids?

<p>Zona Fasciculata (A)</p> Signup and view all the answers

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