Nokea
Which of the following hormones is responsible for the fight-or-flight response?
- A. Epinephrine & norepinephrine
- B. Insulin & glucagon
- C. Estrogen & progesterone
- D. Thyroxin & melatonin
Correct Answer: A
Rationale: The correct answer is A: Epinephrine & norepinephrine. These hormones are responsible for the fight-or-flight response. When facing a threat, the adrenal glands release these hormones, which increase heart rate, blood pressure, and energy levels to prepare the body to either fight or flee. Epinephrine and norepinephrine are part of the sympathetic nervous system's response to stress.
Choices B, C, and D are incorrect:
B: Insulin & glucagon regulate blood sugar levels, not the fight-or-flight response.
C: Estrogen & progesterone are reproductive hormones, not involved in the fight-or-flight response.
D: Thyroxin & melatonin regulate metabolism and sleep-wake cycles, respectively, not the fight-or-flight response.
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In hyperthyroidism, which of the following lab findings would you expect?
- A. Increased TSH, decreased T3, T4
- B. Decreased TSH, increased T3, T4
- C. Increased TSH, increased T3, T4
- D. Decreased TSH, decreased T3, T4
Correct Answer: B
Rationale: The correct answer is B. In hyperthyroidism, the thyroid gland produces an excess of thyroid hormones T3 and T4, leading to negative feedback on the pituitary gland, resulting in decreased TSH levels. Therefore, you would expect decreased TSH and increased T3, T4 levels. A is incorrect because TSH would be decreased, not increased. C is incorrect because TSH would be decreased in hyperthyroidism. D is incorrect because T3 and T4 would be increased in hyperthyroidism.
Adrenaline combination with local anesthetics has the following effects EXCEPT:
- A. Reduces the absorption of local anesthetic
- B. Increases the duration of its local anesthetic activity
- C. Decreases the toxicity of the local anesthetic
- D. Increases blood flow to the injection area
Correct Answer: D
Rationale: Correct Answer: D. Increases blood flow to the injection area.
Rationale:
1. Adrenaline is a vasoconstrictor that reduces blood flow in the injection area.
2. By constricting blood vessels, adrenaline limits the absorption of the local anesthetic, leading to prolonged local action.
3. Adrenaline also helps in reducing the systemic toxicity of the local anesthetic by limiting its absorption.
4. Therefore, the correct answer is D as adrenaline does not increase blood flow to the injection area.
What stimulates the release of PTH from the parathyroid gland?
- A. TSH from the posterior pituitary gland
- B. high levels of calcium in the blood
- C. calcitonin from the anterior pituitary gland
- D. low levels of calcium in the blood
Correct Answer: D
Rationale: The correct answer is D: low levels of calcium in the blood. When calcium levels drop, the parathyroid gland releases parathyroid hormone (PTH) to increase calcium levels in the blood. This is a negative feedback mechanism to maintain calcium homeostasis. A: TSH from the posterior pituitary gland is incorrect because TSH is involved in regulating thyroid function, not PTH release. B: High levels of calcium in the blood would not stimulate PTH release as the body aims to lower, not raise, calcium levels. C: Calcitonin from the anterior pituitary gland is incorrect because calcitonin is released by the thyroid gland and works to lower blood calcium levels, opposing the action of PTH.
Aldosterone:
- A. is a mineralocorticoid secreted by the adrenal cortex.
- B. functions in the regulation of blood glucose levels.
- C. stimulates the kidney to excrete sodium and reabsorb potassium.
- D. All is applicable.
Correct Answer: A
Rationale: Step-by-step rationale for why choice A is correct:
1. Aldosterone is a mineralocorticoid hormone secreted by the adrenal cortex.
2. It plays a key role in regulating electrolyte balance, specifically sodium and potassium levels.
3. Aldosterone acts on the kidneys to increase sodium reabsorption and potassium excretion.
4. This hormone helps to maintain blood pressure and fluid balance in the body.
Summary of why other choices are incorrect:
- Choice B (functions in the regulation of blood glucose levels): Aldosterone does not play a significant role in blood glucose regulation.
- Choice C (stimulates the kidney to excrete sodium and reabsorb potassium): This statement is partially true, but aldosterone actually stimulates sodium reabsorption and potassium excretion.
- Choice D (All is applicable): While aldosterone has various functions, not all statements apply to its actions.
Thyroxine:
- A. is mostly bound to albumin in the plasma, since this has the largest capacity
- B. is 2-5 times more potent that triiodothyronine (T3)
- C. stimulates TSH release
- D. ∼33% is deiodinated in the liver to T3
Correct Answer: D
Rationale: The correct answer is D. Thyroxine is deiodinated in the liver to T3, so approximately 33% of thyroxine is converted to the more active form, triiodothyronine. This conversion is important for regulating metabolic processes in the body. Choices A and C are incorrect because thyroxine is primarily bound to thyroxine-binding globulin in the plasma, not albumin, and it does not stimulate TSH release. Choice B is incorrect because T3 is actually more potent than thyroxine, not the other way around.