The most common second messengers for peptide hormones are ______ and _____.

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: 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.

Correct Answer: A

Rationale: The correct answer is A: adrenal cortex. Cortisol is a glucocorticoid hormone produced by the adrenal cortex. The adrenal cortex is responsible for the synthesis and secretion of cortisol in response to stress. The adrenal medulla produces catecholamines like adrenaline and noradrenaline, not cortisol. The anterior pituitary produces adrenocorticotropic hormone (ACTH), which stimulates cortisol production by the adrenal cortex. The pancreas produces insulin and glucagon, not cortisol. Therefore, the adrenal cortex is the correct choice for the production of cortisol.

Correct Answer: C

Rationale: The correct answer is C, tumor angiogenesis factor. Cancer cells release this growth factor to promote the formation of new blood vessels (angiogenesis) around the tumor, providing a supply of nutrients and oxygen to support their growth. This process is essential for cancer progression. A: Macrophage colony-stimulating factor is involved in the production and differentiation of macrophages, not in angiogenesis. B: Platelet-derived growth factor promotes cell growth and division, but it is not specifically responsible for angiogenesis in the context of cancer. D: Epidermal growth factor is a signaling molecule that promotes cell proliferation and differentiation but is not the primary factor released by cancer cells to induce angiogenesis.

Correct Answer: B

Rationale: The correct answer is B: Androgens. Androgens are male sex hormones responsible for male characteristics like facial hair growth and deepening of voice. Aldosterone (A) is a mineralocorticoid hormone, not a sex hormone. Pheromones (C) are chemical signals, not hormones. Insulin (D) is a hormone that regulates blood sugar levels, not related to sex characteristics. Therefore, B is the correct choice for a male sex hormone.