Nokea
Thyroxine:
- A. is TSH.
- B. is T4.
- C. exerts negative feedback control on the secretion of T3.
- D. lowers basal metabolic rate.
Correct Answer: B
Rationale: Thyroxine is also known as T4, a thyroid hormone produced by the thyroid gland. It plays a crucial role in regulating metabolism. TSH (Thyroid Stimulating Hormone) is a hormone produced by the pituitary gland to stimulate thyroid hormone production, not thyroxine itself. Choice C is incorrect because thyroxine exerts negative feedback on TSH, not T3. Choice D is incorrect as thyroxine actually increases basal metabolic rate. Thus, the correct answer is B as thyroxine is indeed T4.
You may also like to solve these questions
The secretions from which of these glands differs between males and females?
- A. Adrenal.
- B. Parathyroid.
- C. Gonadal.
- D. Pancreas.
Correct Answer: C
Rationale: The correct answer is C: Gonadal. The secretions from gonads (testes in males, ovaries in females) differ between males and females due to the production of sex hormones (testosterone in males, estrogen and progesterone in females). Adrenal glands (A) secrete similar hormones in both genders. Parathyroid (B) and Pancreas (D) do not secrete hormones that differ based on gender.
Which of the following best describes the function of insulin?
- A. Lowers blood glucose levels.
- B. Stimulates cells to make glucose (gluconeogenesis).
- C. Deficiency causes diabetes insipidus.
- D. Decreases blood volume.
Correct Answer: A
Rationale: The correct answer is A: Lowers blood glucose levels. Insulin is a hormone produced by the pancreas that helps regulate blood glucose levels by promoting the uptake of glucose into cells for energy storage. This process reduces the concentration of glucose in the bloodstream. Choices B, C, and D are incorrect because insulin does not stimulate cells to make glucose (B), deficiency does not cause diabetes insipidus (C), and it does not directly affect blood volume (D).
Which of the following is an alpha-blocker used in the treatment of hypertension:
- A. Tyramine
- B. Prazosin
- C. Ergometrine
- D. Ergotamine
Correct Answer: B
Rationale: Step 1: Understand the question is about an alpha-blocker for hypertension.
Step 2: Identify Prazosin as an alpha-blocker used for hypertension by blocking alpha-1 receptors.
Step 3: Explain how Prazosin works to dilate blood vessels and lower blood pressure.
Step 4: Summarize why other choices are incorrect:
- A: Tyramine is not an alpha-blocker, it is found in certain foods.
- C: Ergometrine is an ergot alkaloid used for uterine contractions, not hypertension.
- D: Ergotamine is also an ergot alkaloid used for migraines, not hypertension.
Hyoscine produces all of the following actions EXCEPT:
- A. Sedation
- B. Antiemetic action
- C. Stimulation of the respiratory center
- D. Increase of salivary secretion
Correct Answer: D
Rationale: Hyoscine, also known as scopolamine, is an anticholinergic drug that acts by blocking muscarinic receptors. It produces sedation by crossing the blood-brain barrier and affecting the central nervous system. Its antiemetic action is due to its ability to inhibit the vomiting center in the brain. Stimulation of the respiratory center is not a typical action of hyoscine. Lastly, hyoscine decreases salivary secretion due to its anticholinergic effects. Therefore, the correct answer is D (Increase of salivary secretion) as it is inconsistent with the pharmacological actions of hyoscine.
With respect to calcium metabolism / bone formation:
- A. osteoclasts secrete alkaline phosphatase
- B. osteoblasts are haemopoietic derivatives of monocyte lineage
- C. 1,25(OH)2 ???D3 and PTH stimulate both osteoblasts and osteoclasts
- D. oestrogens are thought to be protective of osteoporosis as their main effect is osteoblasts stimulation
Correct Answer: C
Rationale: Rationale for Correct Answer (C):
1,25(OH)2 D3 and PTH stimulate both osteoblasts and osteoclasts. 1,25(OH)2 D3 enhances calcium absorption in the gut, promotes bone resorption, and stimulates osteoclast activity. PTH increases calcium levels in the blood by enhancing calcium reabsorption in the kidney and stimulating osteoclast activity. Both hormones indirectly stimulate osteoblasts by increasing calcium availability for bone formation.
Summary of Incorrect Choices:
A: Osteoclasts actually secrete acid, not alkaline phosphatase.
B: Osteoblasts are derived from mesenchymal stem cells, not monocytes.
D: Estrogens have a dual effect, inhibiting bone resorption by osteoclasts and stimulating bone formation by osteoblasts; their main effect is inhibiting osteoclast activity, not solely stimulating osteoblasts.