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Which of the following hormones is produced by the adrenal cortex?
- A. Aldosterone
- B. Adrenaline
- C. Glucagon
- D. Calcitonin
Correct Answer: A
Rationale: The correct answer is A: Aldosterone. The adrenal cortex is responsible for producing aldosterone, a hormone that regulates blood pressure and electrolyte balance. Aldosterone is specifically produced in the zona glomerulosa layer of the adrenal cortex. Adrenaline (Choice B) is produced by the adrenal medulla, not the cortex. Glucagon (Choice C) is produced by the pancreas, not the adrenal cortex. Calcitonin (Choice D) is produced by the thyroid gland, not the adrenal cortex. Therefore, the correct answer is A because aldosterone is the hormone produced by the adrenal cortex.
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Which of the following signals would affect local cells by releasing chemicals into the extracellular fluid?
- A. autocrine
- B. paracrine
- C. endocrine
- D. neural
Correct Answer: B
Rationale: The correct answer is B: paracrine. Paracrine signaling involves the release of signaling molecules into the extracellular fluid to affect nearby target cells. This type of signaling is localized and affects cells within close proximity. Autocrine signaling (A) involves cells releasing signals that act on themselves, endocrine signaling (C) involves signaling molecules being released into the bloodstream to affect distant target cells, and neural signaling (D) involves the transmission of signals through neurons. In this case, paracrine signaling specifically targets local cells by releasing chemicals into the extracellular fluid, making it the correct choice.
Why is the posterior pituitary gland called the neurohypophysis?
- A. The posterior pituitary gland is an extension of the hypothalamus.
- B. The neurohypophysis secretes releasing hormones.
- C. The posterior pituitary gland secretes hormones that regulate adenohypophyseal function.
- D. The posterior pituitary gland secretes releasing hormones.
Correct Answer: A
Rationale: The correct answer is A because the posterior pituitary gland is an extension of the hypothalamus. The hypothalamus produces hormones that are stored and released by the posterior pituitary gland. This connection between the two structures allows for direct neural control over hormone release.
Option B is incorrect because the neurohypophysis does not secrete releasing hormones; rather, it releases hormones produced by the hypothalamus. Option C is incorrect because the posterior pituitary gland does not regulate adenohypophyseal function; instead, it stores and releases hormones produced by the hypothalamus. Option D is incorrect because the posterior pituitary gland does not secrete releasing hormones; it releases hormones produced by the hypothalamus.
A congenital condition that includes mental retardation, short disproportional body size, and a thick tongue and neck is caused by __________.
- A. insulin deficiency
- B. deficiency of thymosin
- C. deficiency of thyroxin
- D. excess of synthetic growth hormone
Correct Answer: C
Rationale: Step 1: The congenital condition described points towards a disorder affecting growth and development.
Step 2: The symptoms of mental retardation, short body size, and thick neck suggest hypothyroidism.
Step 3: Thyroxin is a hormone produced by the thyroid gland that regulates metabolism and growth.
Step 4: A deficiency of thyroxin in congenital hypothyroidism leads to the described symptoms.
Step 5: Therefore, the correct answer is C: deficiency of thyroxin.
Summary:
A: Insulin deficiency does not match the symptoms described.
B: Thymosin deficiency is not related to growth and mental retardation.
D: Excess of synthetic growth hormone would not cause mental retardation and thick neck.
Iodine-containing hormones:
- A. include thyroid-stimulating hormone (TSH).
- B. are secreted by the hypothalamus as releasing hormones.
- C. are steroids.
- D. regulate the metabolic rate.
Correct Answer: D
Rationale: The correct answer is D because iodine-containing hormones, such as thyroid hormones, regulate the metabolic rate by influencing the body's energy production and utilization. TSH (choice A) is not an iodine-containing hormone but a pituitary hormone that stimulates the thyroid gland to produce thyroid hormones. Hypothalamus releasing hormones (choice B) are not iodine-containing hormones. Steroids (choice C) are a different class of hormones that do not contain iodine. In summary, choice D is correct as iodine-containing hormones play a crucial role in regulating metabolic rate, while the other choices are incorrect as they do not accurately describe this function.
Selective β2 agonists produce all of the following EXCEPT:
- A. Stimulate β2 > β1
- B. Bronchodilation
- C. Decrease of blood pressure
- D. Stimulate uterine contraction
Correct Answer: D
Rationale: The correct answer is D: Stimulate uterine contraction. Selective β2 agonists primarily target β2 receptors in the lungs, leading to bronchodilation. They have minimal effect on β1 receptors, thus do not significantly impact heart rate or blood pressure. However, β2 receptors in the uterus can cause uterine relaxation, not contraction. Therefore, selective β2 agonists do not stimulate uterine contractions. Choices A, B, and C are incorrect as they align with the typical effects of selective β2 agonists.