Nokea
Testosterone is best described as:
- A. virilizing.
- B. lactogenic.
- C. adenohypophyseal.
- D. pancreatic.
Correct Answer: A
Rationale: Testosterone is best described as virilizing because it is the primary male sex hormone responsible for the development of male characteristics such as facial hair, deep voice, and muscle mass. It plays a key role in virilization. The other choices, lactogenic, adenohypophyseal, and pancreatic, are incorrect because testosterone is not primarily associated with lactation, the anterior pituitary gland, or the pancreas.
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Drug X causes an increase in blood pressure and a decrease in heart rate when administered to a patient intravenously. If an antagonist at ganglionic nicotinic receptors is administered first, drug X causes an increase in blood pressure and an increase in heart rate. Drug X most likely is
- A. Propranolol
- B. Norepinephrine
- C. Isoproterenol
- D. Terbutaline
Correct Answer: B
Rationale: The correct answer is B: Norepinephrine. When an antagonist at ganglionic nicotinic receptors is administered, it blocks the inhibitory effect on sympathetic tone. Since norepinephrine is a sympathetic neurotransmitter that increases blood pressure and heart rate, it is likely that Drug X is norepinephrine. Propranolol (A) is a beta-blocker that decreases heart rate, Isoproterenol (C) is a beta-agonist that increases heart rate, and Terbutaline (D) is a beta-agonist that also increases heart rate. These choices do not align with the observed effects of Drug X when the ganglionic nicotinic receptor antagonist is administered.
Anti-cholinesterase drugs include the following drugs EXCEPT:
- A. Physostigmine
- B. Carbachol
- C. Metrifonate
- D. Neostigmine
Correct Answer: B
Rationale: The correct answer is B: Carbachol. Anti-cholinesterase drugs inhibit the enzyme acetylcholinesterase, increasing levels of acetylcholine. Carbachol is a direct cholinergic agonist, not an anti-cholinesterase drug. Physostigmine, Metrifonate, and Neostigmine are all anti-cholinesterase drugs that work by inhibiting acetylcholinesterase. Physostigmine is used for glaucoma and atropine overdose, Metrifonate for parasitic infections, and Neostigmine for myasthenia gravis.
Which artery generally gives rise to inferior thyroid artery?
- A. Arch of aorta
- B. Brachiocephalic artery
- C. External carotid artery
- D. Thyrocervical trunk
Correct Answer: D
Rationale: The correct answer is D, the thyrocervical trunk. This artery generally gives rise to the inferior thyroid artery. The thyrocervical trunk is a branch of the subclavian artery, supplying blood to the thyroid gland. The other choices are incorrect because the arch of aorta does not give rise to the inferior thyroid artery, the brachiocephalic artery does not directly supply the thyroid gland, and the external carotid artery does not typically provide blood to the thyroid gland. Therefore, the thyrocervical trunk is the most likely source for the inferior thyroid artery.
Cells that respond to peptide hormones usually do so through a sequence of biochemical reactions involving receptor and kinase activation. In order for cells to respond, it is necessary for first and second messengers to communicate. This is possible because ________.
- A. peptide hormones always enter the cell membrane and elicit a response without assistance from other messengers
- B. hormones alter cellular operations through stimulation of a gene directly
- C. G protein acts as the link between first and second messengers
- D. the hormone receptor complex moves into the cytoplasm as a unit
Correct Answer: C
Rationale: The correct answer is C: G protein acts as the link between first and second messengers.
Rationale:
1. Peptide hormones cannot enter the cell membrane due to their large size.
2. Hormones do not directly stimulate genes; they act through signaling pathways.
3. G proteins are key in transmitting signals from hormone receptors to second messengers, facilitating cellular responses.
4. The hormone receptor complex typically stays on the cell membrane to initiate signaling cascades.
Growth hormone ________.
- A. is also called somatostatin
- B. is regulated by humoral mechanisms
- C. secretion results in a decrease in muscle mass
- D. promotes long bone growth during the formative years
Correct Answer: D
Rationale: The correct answer is D because growth hormone promotes long bone growth during the formative years by stimulating the growth plates in bones. This hormone plays a crucial role in skeletal growth and development. Choice A is incorrect because somatostatin is a different hormone that inhibits growth hormone release. Choice B is incorrect because growth hormone is primarily regulated by neural mechanisms. Choice C is incorrect because growth hormone actually promotes muscle growth and reduces fat mass.