Which of the following is not a change that may be caused by hormonal stimulus?

Correct Answer: D

Rationale: The correct answer is D: direct control of the nervous system. Hormonal stimuli typically target specific cells or tissues to elicit a response, such as changes in membrane potential, genetic events leading to protein synthesis, or an increase in enzymatic activity. Hormones do not directly control the nervous system, as the nervous system operates independently and responds to its own set of stimuli. Therefore, D is the correct answer as it does not align with the typical effects of hormonal stimulation. Choices A, B, and C are incorrect as they are all changes that can be caused by hormonal stimuli.

Correct Answer: C

Rationale: The correct answer is C: liver. The liver does not produce hormones. Hormones are primarily produced by endocrine glands such as the pituitary, thyroid, adrenal glands, etc. The liver's main functions are related to metabolism, detoxification, and storage, rather than hormone production. The heart (choice A) produces hormones like atrial natriuretic peptide. The kidney (choice B) produces hormones like erythropoietin and renin. The skin (choice D) produces hormones like vitamin D when exposed to sunlight. Therefore, the liver is the only organ in the list that does not have hormone production.

Correct Answer: C

Rationale: The correct answer is C: cAMP and calcium. Peptide hormones bind to their receptors on the cell surface, activating G-proteins which then trigger the production of cAMP as a second messenger. cAMP then further activates protein kinases to initiate various cellular responses. Calcium is also a common second messenger in peptide hormone signaling pathways, regulating processes like muscle contraction and gene expression. Choice A is incorrect because peptide hormones themselves are not second messengers. Choice B is incorrect as glucose is not a common second messenger for peptide hormones. Choice D is incorrect as sodium is not typically involved in peptide hormone signaling pathways.

Correct Answer: B

Rationale: Step 1: The hormones produced by the hypothalamus and secreted by the posterior pituitary are ADH (vasopressin) and oxytocin. Step 2: ADH regulates water balance by increasing water reabsorption in the kidneys. Step 3: Oxytocin is involved in uterine contractions during childbirth and milk ejection during breastfeeding. Step 4: Therefore, choice B (ADH and oxytocin) is correct. Summary: - Choice A (ADH and aldosterone) is incorrect because aldosterone is produced by the adrenal glands, not the posterior pituitary. - Choice C (oxytocin and prolactin) is incorrect because prolactin is produced by the anterior pituitary. - Choice D (cortisol and aldosterone) is incorrect because cortisol is produced by the adrenal glands, not the posterior pituitary.

Correct Answer: C

Rationale: The correct answer is C: myxedema. Hypothyroidism in adults is commonly caused by an underactive thyroid gland, leading to decreased production of thyroid hormones. Myxedema is the term used to describe severe hypothyroidism, characterized by symptoms such as fatigue, weight gain, cold intolerance, and swelling of the face and hands. Graves disease (choice A) is actually a cause of hyperthyroidism, not hypothyroidism. Diabetes insipidus (choice B) is a disorder related to the kidneys and has no direct connection to thyroid function. Acromegaly (choice D) is caused by excess growth hormone production, unrelated to thyroid function. Therefore, the correct choice is C as it accurately describes hypothyroidism in adults.