The Action of Parathormone in the Human Body

Correct Answer: D

Rationale: The correct answer is D: Increases blood calcium level. Parathormone is released by the parathyroid glands in response to low blood calcium levels. It acts to increase blood calcium levels by stimulating the release of calcium from bones, increasing calcium absorption in the intestines, and promoting calcium reabsorption in the kidneys. This helps to maintain proper calcium levels in the body. Choices A, B, and C are incorrect because parathormone does not have any direct effect on blood sodium levels and actually works to increase, not decrease, blood calcium levels.

Correct Answer: A

Rationale: The correct answer is A: Oestrogen. Ovaries secrete oestrogen, a key female sex hormone involved in the development of secondary sexual characteristics, regulation of the menstrual cycle, and maintenance of pregnancy. Luteinising hormone (B) and follicle stimulating hormone (C) are secreted by the pituitary gland to regulate ovarian function. Oxytocin (D) is produced by the hypothalamus and released by the pituitary gland for uterine contractions and milk ejection, not by the ovaries. Therefore, A is correct as ovaries primarily produce oestrogen.

Correct Answer: B

Rationale: The correct answer is B: vagus. The efferent swallow reflex involves motor nerves responsible for swallowing. The vagus nerve is primarily responsible for the afferent (sensory) pathway in the swallow reflex, while the efferent pathway involves the trigeminal, facial, and hypoglossal nerves. The trigeminal nerve (A) controls chewing muscles, the facial nerve (C) is responsible for facial expressions and some swallowing muscles, and the hypoglossal nerve (D) controls the movement of the tongue during swallowing. Therefore, the vagus nerve is not directly involved in the efferent motor control of swallowing, making it the correct answer.

Correct Answer: A

Rationale: The correct answer is A because gastrin primarily stimulates gastric acid secretion and gastric mucosal growth but not insulin secretion. Gastrin acts on parietal cells to stimulate acid production and chief cells to release pepsinogen. Choice B and C are incorrect as gastrin does have a trophic effect on colonic and gastric mucosa, respectively. Choice D is also incorrect as gastrin stimulates pepsin secretion.

Correct Answer: D

Rationale: The correct answer is D because creatinine excretion is not depressed in starvation. Creatinine is a byproduct of muscle metabolism and is relatively constant even during starvation when muscle breakdown occurs. A: Incorrect, as increasing respiratory quotient > 1.0 indicates excessive carbohydrate utilization. B: Incorrect, SDA is the energy used for digestion and absorption of nutrients, not specific to protein metabolism. C: Incorrect, glucagon stimulates protein breakdown to release amino acids for energy during fasting.