Nokea
The most common second messengers for peptide hormones are ______ and _____.
- A. peptide hormones and calcium.
- B. calcium and glucose.
- C. cAMP and calcium.
- D. cAMP and sodium.
Correct Answer: C
Rationale: The correct answer is C: cAMP and calcium. Peptide hormones bind to their receptors on the cell surface, activating G-proteins which then trigger the production of cAMP as a second messenger. cAMP then further activates protein kinases to initiate various cellular responses. Calcium is also a common second messenger in peptide hormone signaling pathways, regulating processes like muscle contraction and gene expression. Choice A is incorrect because peptide hormones themselves are not second messengers. Choice B is incorrect as glucose is not a common second messenger for peptide hormones. Choice D is incorrect as sodium is not typically involved in peptide hormone signaling pathways.
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Which pair contains two of these colours in order of increasing frequency (lower frequency first)?
- A. green, red
- B. green, violet
- C. violet, yellow
- D. yellow, red
Correct Answer: B
Rationale: The correct answer is B (green, violet) because green has a lower frequency than violet in the visible light spectrum. Green light has a wavelength longer than violet light, meaning it has lower frequency. This is based on the electromagnetic spectrum where colors are arranged in order of increasing frequency from red (lowest) to violet (highest). Other choices are incorrect because they do not follow the order of increasing frequency as per the visible light spectrum.
Hypertensive effect of adrenaline is reversed by:
- A. Propranolol
- B. Phenylephrine
- C. Prazosin
- D. Amphetamine
Correct Answer: C
Rationale: Step-by-step rationale:
1. Adrenaline causes vasoconstriction leading to increased blood pressure.
2. Prazosin is an alpha-1 adrenergic receptor antagonist.
3. By blocking alpha-1 receptors, prazosin reverses the vasoconstrictive effects of adrenaline.
4. Propranolol (A) is a non-selective beta-blocker and would not directly counteract adrenaline's vasoconstrictive effects.
5. Phenylephrine (B) is a vasoconstrictor itself and would further exacerbate the hypertensive effect of adrenaline.
6. Amphetamine (D) is a sympathomimetic drug that would also enhance the hypertensive effects of adrenaline.
Summary:
Prazosin (C) is the correct answer as it specifically targets the alpha-1 adrenergic receptors responsible for the hypertensive effects of adrenaline. Propranolol, phenylephrine, and amphetamine would
Name the structure that prevents food from entering the lungs?
- A. Pyloric sphincter
- B. Trachea
- C. Pharynx
- D. Epiglottis
Correct Answer: D
Rationale: The correct answer is D: Epiglottis. The epiglottis is a flap of tissue that covers the trachea during swallowing, preventing food from entering the lungs. When food is swallowed, the epiglottis closes off the trachea to ensure that the food goes down the esophagus into the stomach.
Incorrect choices:
A: The pyloric sphincter is a valve located between the stomach and the small intestine, regulating the flow of partially digested food.
B: The trachea is the windpipe that connects the larynx to the bronchi, allowing air to pass into the lungs.
C: The pharynx is the throat area where the pathways for both food and air cross, but it is the epiglottis that specifically prevents food from entering the lungs.
Which is not Na+ dependent for absorption?
- A. thiamin
- B. riboflavin
- C. niacin
- D. folate
Correct Answer: D
Rationale: The correct answer is D. Folate absorption is not Na+ dependent because it is absorbed in the small intestine through a carrier-mediated process independent of sodium. Thiamin, riboflavin, and niacin require sodium-dependent transport mechanisms for absorption in the small intestine. Thiamin is absorbed through thiamin transporters that are Na+ dependent. Riboflavin is absorbed by sodium-dependent multivitamin transporters. Niacin absorption also involves sodium-dependent transporters. Therefore, folate is the only option that is not Na+ dependent for absorption.
Two terms that are paired incorrectly are .
- A. cortisol-adrenal cortex
- B. androgens-adrenal cortex
- C. calcitonin-thyroid
- D. corticosteroid-adrenal medulla
Correct Answer: D
Rationale: The correct answer is D because corticosteroids are produced by the adrenal cortex, not the adrenal medulla. Cortisol is a type of corticosteroid, making choice A incorrect. Androgens are indeed produced by the adrenal cortex, making choice B correct. Calcitonin is produced by the thyroid, not the adrenal cortex, making choice C incorrect. Therefore, the only pair that is incorrect is corticosteroid and adrenal medulla.