Nokea
Gastrin secretion is stimulated by all but:
- A. luminal peptides
- B. vagal discharge
- C. luminal acid
- D. phenylalanine
Correct Answer: C
Rationale: The correct answer is C: luminal acid. Gastrin secretion is primarily stimulated by the presence of luminal peptides and vagal discharge. Luminal acid inhibits gastrin secretion through negative feedback mechanisms. Phenylalanine does not directly stimulate gastrin secretion. In summary, luminal acid is the correct answer because it acts as an inhibitory factor for gastrin secretion, whereas the other choices are known stimulatory factors.
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Which of the pairs of hormones BOTH increase blood sugar?
- A. insulin and glucagon
- B. growth hormone and insulin
- C. glucagon and epinephrine
- D. antidiuretic hormone and glucagon
Correct Answer: C
Rationale: The correct answer is C, glucagon and epinephrine. Glucagon stimulates the liver to release glucose into the bloodstream, increasing blood sugar levels. Epinephrine, also known as adrenaline, has a similar effect by promoting the breakdown of glycogen into glucose. Insulin (choice A) decreases blood sugar by promoting glucose uptake into cells. Growth hormone (choice B) mainly affects growth and metabolism but doesn't directly increase blood sugar. Antidiuretic hormone (choice D) regulates water balance and has no direct effect on blood sugar levels.
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.
Which one of the following properties makes labetalol different from nearly all the other β-blockers on the market?
- A. Also blocks alpha-adrenergic receptors
- B. Causes strong atropine-like side effects, has same side effects as atropine
- C. Only blocks β1 receptors
- D. Safe for asthmatics because it lacks β2 blocking activity
Correct Answer: A
Rationale: The correct answer is A because labetalol is unique among most β-blockers as it also blocks alpha-adrenergic receptors. This dual action results in vasodilation and reduced blood pressure. Choice B is incorrect as labetalol does not cause atropine-like side effects. Choice C is incorrect as labetalol blocks both β1 and β2 receptors. Choice D is also incorrect as labetalol does have some β2 blocking activity, making it not entirely safe for asthmatics.
Which statement about the reaction is correct?
- A. It is endothermic and thermal energy is absorbed from the surroundings.
- B. It is endothermic and thermal energy is transferred to the surroundings.
- C. It is exothermic and thermal energy is absorbed from the surroundings.
- D. It is exothermic and thermal energy is transferred to the surroundings.
Correct Answer: A
Rationale: The correct answer is A because an endothermic reaction absorbs thermal energy from the surroundings to proceed. In an endothermic reaction, the products have higher potential energy than the reactants, requiring energy input. Choice B is incorrect as endothermic reactions do not transfer thermal energy to the surroundings. Choices C and D are incorrect as they describe exothermic reactions, where thermal energy is released to the surroundings.
A 43-year-old woman with diagnosed myasthenia gravis presents with profound skeletal muscle weakness. We are unsure whether she is experiencing a cholinergic crisis or a myasthenic crisis, so we administer a usually appropriate dose of parenteral edrophonium. Assume the patient was actually experiencing a cholinergic crisis. Which of the following is the most likely response to the drug?
- A. Hypertensive crisis from peripheral vascular constriction
- B. Myocardial ischemia, and angina, from drug-induced tachycardia and coronary vasoconstriction
- C. Premature ventricular contractions from increased ventricular automaticity
- D. Ventilatory distress or failure
Correct Answer: D
Rationale: The correct answer is D: Ventilatory distress or failure. Edrophonium is a short-acting acetylcholinesterase inhibitor used to differentiate between myasthenic and cholinergic crises. In a cholinergic crisis, which is an excess of acetylcholine, administering edrophonium can worsen symptoms due to further acetylcholine accumulation. This can lead to excessive stimulation of the respiratory muscles, resulting in ventilatory distress or failure.
Choice A is incorrect because cholinergic crisis typically causes hypotension, not hypertension. Choice B is incorrect because edrophonium-induced tachycardia can worsen myocardial ischemia, not angina. Choice C is incorrect because increased ventricular automaticity would not be a common response to edrophonium in a cholinergic crisis.