Nokea
Which is WRONG about dopamine:
- A. Is effective orally
- B. Metabolized by MAO and COMT mainly
- C. Excreted in urine as vanillylmandelic acid
- D. Stimulates α, β1, and D receptors
Correct Answer: A
Rationale: The correct answer is A because dopamine is not effective orally due to its inability to cross the blood-brain barrier. Dopamine is mainly metabolized by MAO and COMT enzymes (B). It is primarily excreted in the urine as homovanillic acid, not vanillylmandelic acid (C). Dopamine stimulates dopamine receptors (D), not α, β1, and D receptors.
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Steroid hormones function by binding to receptor proteins within the ________. Once the hormone binds to a receptor, it activates ______.
- A. nucleus: a second messenger
- B. nucleus: particular genes
- C. plasma membrane: a second messenger
- D. plasma membrane: particular genes
Correct Answer: B
Rationale: The correct answer is B because steroid hormones bind to receptor proteins in the nucleus, forming a hormone-receptor complex that directly influences the expression of specific genes. This process leads to the activation or repression of particular genes, resulting in changes in cellular functions. Choices A and C are incorrect because steroid hormones do not bind to receptors in the plasma membrane or use second messengers for signal transduction. Choice D is incorrect as steroid hormones do not directly regulate genes at the plasma membrane level.
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
The pituitary hormone that stimulates the male testes to produce sperm and stimulates the development of the follicle in the female on a monthly cycle is:
- A. growth hormone
- B. luteinizing hormone
- C. prolactin
- D. follicle-stimulating hormone
Correct Answer: D
Rationale: The correct answer is D: follicle-stimulating hormone (FSH). FSH is produced by the pituitary gland and plays a crucial role in both male and female reproductive systems. In males, FSH stimulates the testes to produce sperm. In females, FSH stimulates the development of ovarian follicles, which contain eggs. This hormone is essential for the process of ovulation and the menstrual cycle.
A: Growth hormone is not directly involved in the reproductive system but rather promotes overall growth and development.
B: Luteinizing hormone (LH) is responsible for ovulation and the production of testosterone in males. It does not directly stimulate sperm production or follicle development.
C: Prolactin is primarily involved in milk production and has no direct role in sperm production or follicle development.
Match the correct hormone pair that have antagonistic effects?
- A. Calcitonin-parathyroid hormone
- B. Glucagon-gastrin
- C. Estrogen-testosterone
- D. Gonadotropic releasing hormone-luteinizing hormone
Correct Answer: a
Rationale: The correct answer is A: Calcitonin-parathyroid hormone.
1. Calcitonin lowers blood calcium levels by inhibiting bone breakdown, while parathyroid hormone raises blood calcium levels by stimulating bone breakdown.
2. This hormone pair directly opposes each other in regulating blood calcium levels.
3. Choices B, C, and D do not involve hormones with antagonistic effects on the same physiological process.
Insufficient Levels of Thyroid Hormone in Adults Cause-------------
- A. Goiter
- B. Tetany
- C. Myxedema
- D. Cretinism
Correct Answer: C
Rationale: The correct answer is C: Myxedema. Insufficient levels of thyroid hormone in adults lead to myxedema due to decreased metabolism and energy production. Goiter (A) is the enlargement of the thyroid gland, not caused by low thyroid hormone levels. Tetany (B) is muscle spasms due to low calcium levels, not related to thyroid hormone deficiency. Cretinism (D) is a condition of severe hypothyroidism in infants, not in adults. Therefore, the correct choice is C as it directly relates to the consequences of low thyroid hormone levels in adults.