Nokea
The rate of metabolism of all body cells is regulated by _______.
- A. parathyroid hormone
- B. aldosterone
- C. calcitonin
- D. thyroid hormone
Correct Answer: D
Rationale: The correct answer is D: thyroid hormone. Thyroid hormone plays a crucial role in regulating the rate of metabolism in all body cells by influencing the production of enzymes involved in energy production. It increases the body's metabolic rate, affecting processes such as heart rate, temperature regulation, and energy expenditure. Parathyroid hormone (A) regulates calcium levels, aldosterone (B) regulates electrolyte balance, and calcitonin (C) regulates calcium metabolism, but they do not directly influence overall metabolism rate in all body cells. Thyroid hormone is the primary hormone responsible for controlling metabolism throughout the body.
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All but one of the following compounds releases large amounts of energy on breakdown:
- A. cAMP
- B. ATP
- C. creatine phosphate
- D. ADP
Correct Answer: A
Rationale: The correct answer is A: cAMP. cAMP, or cyclic adenosine monophosphate, does not release large amounts of energy on breakdown compared to the other choices. Here's the rationale:
1. ATP (Choice B) is known as the energy currency of the cell and releases a significant amount of energy when broken down.
2. Creatine phosphate (Choice C) is a high-energy compound that can rapidly donate its phosphate group to regenerate ATP.
3. ADP (Choice D) releases energy when converted to ATP through phosphorylation.
4. cAMP (Choice A) is a secondary messenger involved in signal transduction and does not store or release energy like ATP or creatine phosphate.
Regarding iron:
- A. it is more readily absorbed in the ferric form
- B. men lose about 0.6mg/d
- C. average daily iron intake is 40mg
- D. ascorbic acid reduces iron absorption
Correct Answer: B
Rationale: The correct answer is B because men lose about 0.6mg of iron per day through various physiological processes like shedding skin cells and hair. This loss must be replenished through dietary intake to maintain iron balance. Choice A is incorrect as iron is more readily absorbed in the ferrous form. Choice C is incorrect as the average daily iron intake is around 18mg. Choice D is incorrect ascorbic acid enhances iron absorption rather than reducing it.
You are a resident in a hospital in a very poor part of the world. Their drug selection is limited. A patient presents with acute cardiac failure, for which your preferred drug is dobutamine, given intravenously. However, there is none available. Which of the following other drugs, or combination of drugs, would be a suitable alternative?
- A. Dopamine (at a very high dose)
- B. Ephedrine
- C. Ephedrine plus propranolol
- D. Norepinephrine plus phentolamine
Correct Answer: D
Rationale: The correct answer is D: Norepinephrine plus phentolamine. Norepinephrine is a potent vasopressor that can increase blood pressure and cardiac output in acute cardiac failure. Phentolamine is an alpha-blocker that can help counteract the vasoconstrictive effects of norepinephrine.
Rationale:
1. Norepinephrine: Increases blood pressure and cardiac output, improving perfusion to vital organs in acute cardiac failure.
2. Phentolamine: Counteracts the vasoconstrictive effects of norepinephrine, preventing excessive vasoconstriction.
Summary:
A: Dopamine at a very high dose may not be as effective as norepinephrine in acute cardiac failure.
B: Ephedrine is a less potent vasopressor compared to norepinephrine.
C: Ephedrine plus propranolol combination may lead to conflicting effects on blood pressure and heart rate
Which is NOT part of the normal content of gastric juice?
- A. HPO42-
- B. mucus
- C. lipase
- D. amylase
Correct Answer: D
Rationale: The correct answer is D: amylase. Gastric juice primarily consists of hydrochloric acid, pepsin, and mucus. Amylase is an enzyme produced in the pancreas, not in the stomach. It functions in the small intestine to break down carbohydrates. Therefore, amylase is not a normal component of gastric juice. Choices A, B, and C are incorrect because HPO42- (phosphate ions), mucus, and lipase are all typically found in gastric juice.
Calcitonin and parathyroid hormone:
- A. are both secreted by the parathyroid glands.
- B. increase plasma levels of calcium.
- C. decrease plasma levels of calcium.
- D. control plasma levels of calcium.
Correct Answer: D
Rationale: Correct Answer: D
Rationale: Calcitonin and parathyroid hormone regulate plasma calcium levels. Calcitonin decreases calcium levels by inhibiting bone breakdown, while parathyroid hormone increases calcium levels by stimulating bone breakdown and increasing calcium reabsorption. Therefore, both hormones work together to maintain calcium homeostasis. The correct answer, choice D, highlights that both hormones control plasma calcium levels.
Summary of Other Choices:
A: Incorrect. Calcitonin is secreted by the thyroid gland, not the parathyroid glands.
B: Incorrect. Calcitonin decreases plasma calcium levels, while parathyroid hormone increases plasma calcium levels.
C: Incorrect. Parathyroid hormone increases plasma calcium levels, whereas calcitonin decreases plasma calcium levels.