Nokea
Iodination of thyroid hormones is mediated by __________.
- A. lysosomes in the cell
- B. the Golgi apparatus
- C. colloid endocytosis
- D. peroxidase enzymes
Correct Answer: D
Rationale: The correct answer is D: peroxidase enzymes. Peroxidase enzymes are responsible for catalyzing the iodination process of thyroid hormones in the thyroid gland. They facilitate the incorporation of iodine atoms into tyrosine residues within thyroglobulin to form thyroid hormones T3 and T4. Lysosomes (choice A) are involved in cellular waste disposal, not iodination. The Golgi apparatus (choice B) is responsible for processing and packaging proteins, not iodination. Colloid endocytosis (choice C) is the process of internalizing colloid-containing vesicles in thyroid follicular cells, but it is not directly involved in iodination.
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Mineralocorticoid is to aldosterone as glucocorticoid is to ________.
- A. testosterone
- B. estrogen
- C. cortisol
- D. epinephrine
Correct Answer: C
Rationale: Mineralocorticoids regulate electrolyte and fluid balance, with aldosterone being the primary mineralocorticoid. Glucocorticoids regulate metabolism and immune response, with cortisol being the primary glucocorticoid. Therefore, the correct answer is C: cortisol. Testosterone (A) and estrogen (B) are sex hormones, not corticosteroids. Epinephrine (D) is a hormone produced by the adrenal medulla, not a corticosteroid.
An autoimmune form of hypothyroidism when the body destroys the thyroid cells is called
- A. Hashimoto's disease.
- B. Graves disease.
- C. myxedema.
- D. acromegaly
Correct Answer: A
Rationale: Rationale:
1. Hashimoto's disease is characterized by the immune system attacking the thyroid gland, leading to hypothyroidism.
2. It is an autoimmune condition where the body produces antibodies that target and destroy thyroid cells.
3. This results in a decrease in thyroid hormone production.
4. Graves disease (choice B) is a form of hyperthyroidism caused by an overactive thyroid gland.
5. Myxedema (choice C) refers to severe hypothyroidism but is not autoimmune.
6. Acromegaly (choice D) is a disorder caused by excess growth hormone production, unrelated to thyroid function.
An organ that can be classified as both an endocrine and exocrine gland is the
- A. hypothalamus.
- B. thymus gland.
- C. pancreas.
- D. pituitary gland.
Correct Answer: C
Rationale: The correct answer is C: pancreas. The pancreas is classified as both an endocrine gland, producing hormones like insulin and glucagon, and an exocrine gland, secreting digestive enzymes into the small intestine. This dual functionality makes it unique among the other options. The hypothalamus (A) is primarily an endocrine gland involved in hormone regulation, while the thymus gland (B) is solely an endocrine gland responsible for T-cell maturation. The pituitary gland (D) is also an endocrine gland that regulates various bodily functions but does not have exocrine functions like the pancreas.
What do the following hormones have in common: growth hormone, cortisol, and epinephrine? All:
- A. are secreted by the adrenal glands.
- B. raise blood glucose.
- C. suppress gluconeogenesis.
- D. are steroids.
Correct Answer: B
Rationale: Step-by-step rationale for why choice B is correct:
1. Growth hormone, cortisol, and epinephrine all raise blood glucose levels.
2. Growth hormone promotes glucose production, cortisol increases blood sugar through gluconeogenesis, and epinephrine stimulates glycogen breakdown.
3. The increase in blood glucose is essential for providing energy during stress or physical activity.
4. None of the other choices align with all three hormones' functions, making choice B the correct answer.
Summary: Choices A and D are incorrect because not all three hormones are secreted by the adrenal glands or are steroids. Choice C is incorrect as these hormones do not suppress gluconeogenesis; instead, they promote processes that raise blood glucose levels.
Botulism is a serious and sometimes fatal disorder caused by Botulinum toxin. How is Botulinum toxin exerting its effects?
- A. Massive release of adrenaline from the adrenal medulla
- B. Blockade of alpha and beta adrenergic receptors
- C. Stimulation of acetylcholinesterase enzyme
- D. Blockade of acetylcholine release from all cholinergic nerves
Correct Answer: D
Rationale: The correct answer is D: Blockade of acetylcholine release from all cholinergic nerves. Botulinum toxin exerts its effects by inhibiting the release of acetylcholine from presynaptic nerve terminals at neuromuscular junctions. This leads to muscle paralysis, which is a characteristic feature of botulism.
A: Massive release of adrenaline from the adrenal medulla is incorrect because botulinum toxin does not affect the adrenal medulla or adrenaline release.
B: Blockade of alpha and beta adrenergic receptors is incorrect because botulinum toxin does not directly block adrenergic receptors.
C: Stimulation of acetylcholinesterase enzyme is incorrect because botulinum toxin inhibits acetylcholine release rather than stimulating acetylcholinesterase.
In summary, the correct answer D directly correlates with the mechanism of action of Botulinum toxin, while the other choices are unrelated to how Botulinum toxin exerts