Nokea
The anterior pituitary gland receives hormone messages from the hypothalamus via ________.
- A. a capillary network
- B. neurons that extend from the hypothalamus to the pituitary
- C. Schwann cells
- D. both a and b
Correct Answer: A
Rationale: The correct answer is A: a capillary network. The hypothalamus secretes hormones into the capillary network called the hypothalamic-hypophyseal portal system. These hormones travel directly to the anterior pituitary gland to regulate the release of its own hormones. Choice B is incorrect because neurons do not directly connect the hypothalamus and pituitary gland. Choice C is incorrect because Schwann cells are involved in myelination of peripheral nerves, not hormone transport. Choice D is incorrect because although both options A and B involve communication between the hypothalamus and pituitary gland, it is specifically the capillary network that carries hormone messages in this case.
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Which row identifies the product at each electrode?
- A. bromide ions, lead ions
- B. bromine, lead
- C. lead ions, bromide ions
- D. lead, bromine
Correct Answer: D
Rationale: The correct answer is D because lead is the product at the cathode (negative electrode) during electrolysis, while bromine is the product at the anode (positive electrode). Lead is reduced at the cathode to form lead metal, and bromine is oxidized at the anode to form bromine gas. This is in line with the general rule that cations are attracted to the cathode and are reduced, while anions are attracted to the anode and are oxidized.
Choice A is incorrect as bromide ions are reduced at the cathode, not lead ions. Choice B is incorrect because bromine is produced at the anode, not lead. Choice C is incorrect because lead ions are reduced at the cathode, not bromide ions.
How do hormones from the thyroid and parathyroid regulate the calcium concentration of the blood?
- A. Calcitonin lowers blood calcium; parathyroid hormone raises blood calcium.
- B. Parathyroid hormone lowers blood calcium; calcitonin raises blood calcium.
- C. Thyroxine and triiodothyronine together regulate calcium levels, as needs dictate.
- D. Both parathroid hormone and the three thyroid hormones function to regulate blood calcium levels.
Correct Answer: A
Rationale: Step 1: Calcitonin is secreted by the thyroid gland and lowers blood calcium levels by promoting calcium deposition in bones.
Step 2: Parathyroid hormone (PTH) is secreted by the parathyroid gland and raises blood calcium levels by stimulating bone resorption and increasing calcium reabsorption in the kidneys.
Step 3: Since Calcitonin lowers blood calcium and PTH raises blood calcium, choice A is correct.
Summary: Choices B, C, and D are incorrect as they provide inaccurate information about the roles of calcitonin, PTH, thyroxine, and triiodothyronine in regulating blood calcium levels.
All of the following are β-adrenergic agonists EXCEPT:
- A. Adrenaline
- B. Dopamine
- C. Noradrenaline
- D. Phenylephrine
Correct Answer: D
Rationale: The correct answer is D: Phenylephrine. Beta-adrenergic agonists stimulate beta-adrenergic receptors. Phenylephrine is an alpha-adrenergic agonist, not a beta-adrenergic agonist. Adrenaline, dopamine, and noradrenaline are all beta-adrenergic agonists. Therefore, the correct answer is D.
Cushing syndrome and Addison’s disease are:
- A. forms of chronic adrenal cortical hypofunction.
- B. forms of chronic adrenal cortical hypersecretion.
- C. treated with replacement doses of cortisol (i.e., prednisone).
- D. disorders of the adrenal cortex.
Correct Answer: D
Rationale: The correct answer is D because both Cushing syndrome and Addison's disease are disorders of the adrenal cortex. Cushing syndrome involves excessive cortisol production, while Addison's disease is characterized by insufficient cortisol production. Both conditions directly affect the adrenal cortex, leading to hormonal imbalances.
Choice A is incorrect because Cushing syndrome involves hyperfunction, not hypofunction. Choice B is incorrect as it states hypersecretion, which is true for Cushing syndrome but not for Addison's disease. Choice C is incorrect because while replacement cortisol therapy is used for Addison's disease, it is not the only treatment option, and it does not apply to Cushing syndrome.
Which of the following suppress(es) the secretion of ACTH?
- A. Elevated blood glucose levels
- B. Dietary iodine
- C. Corticotropin-releasing hormone (CRH)
- D. Elevated plasma cortisol levels
Correct Answer: D
Rationale: Elevated plasma cortisol levels suppress the secretion of ACTH through negative feedback. High cortisol levels signal the hypothalamus and pituitary to decrease the release of CRH and ACTH, respectively, to maintain homeostasis. This is a regulatory mechanism to prevent excessive cortisol production.
A: Elevated blood glucose levels do not directly suppress ACTH secretion.
B: Dietary iodine is not related to ACTH secretion.
C: CRH stimulates ACTH release, so it does not suppress its secretion.