Nokea
In relation to the molecular mechanism of action of sympathomimetics, the following is CORRECT:
- A. Beta receptor stimulation increases c-GMP
- B. Alpha 2 receptor stimulation stimulates adenyl cyclase
- C. Alpha 2 receptor stimulation increases c-AMP
- D. Alpha 1 receptor stimulation releases IP3 and DAG
Correct Answer: D
Rationale: The correct answer is D: Alpha 1 receptor stimulation releases IP3 and DAG. When alpha 1 receptors are stimulated by sympathomimetics, they activate G-proteins which then stimulate phospholipase C. Phospholipase C cleaves phosphatidylinositol 4,5-bisphosphate (PIP2) into inositol trisphosphate (IP3) and diacylglycerol (DAG). IP3 triggers the release of calcium from intracellular stores, leading to smooth muscle contraction, while DAG activates protein kinase C to initiate various cellular responses. Choices A, B, and C are incorrect because beta receptor stimulation increases cAMP, alpha 2 receptor stimulation inhibits adenyl cyclase leading to decreased cAMP levels, and alpha 2 receptor stimulation does not increase cAMP.
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The hormone that stimulates the contraction of smooth muscle in the uterus is .
- A. follicle-stimulating hormone
- B. oxytocin
- C. prolactin
- D. luteinizing hormone
Correct Answer: B
Rationale: The correct answer is B: oxytocin. Oxytocin is the hormone responsible for stimulating the contraction of smooth muscle in the uterus during childbirth and labor. It acts on the smooth muscle cells in the uterine wall, causing them to contract and aiding in the process of childbirth.
A: Follicle-stimulating hormone is involved in the regulation of the reproductive system, particularly in the development of ovarian follicles.
C: Prolactin is primarily responsible for milk production in the mammary glands.
D: Luteinizing hormone triggers ovulation and the formation of the corpus luteum in the ovary.
Therefore, the correct answer is B because it directly affects the contraction of smooth muscle in the uterus, which is essential during childbirth.
The major targets of growth hormone are ________.
- A. the blood vessels
- B. the adrenal glands
- C. the liver
- D. bones and skeletal muscles
Correct Answer: D
Rationale: The correct answer is D: bones and skeletal muscles. Growth hormone primarily targets these tissues to promote growth and development. Growth hormone stimulates bone growth by acting on bone cells and increasing protein synthesis in skeletal muscles, leading to muscle growth. The other choices are incorrect because growth hormone does not directly target blood vessels, adrenal glands, or the liver for growth-promoting effects. Growth hormone primarily affects bone and muscle tissues for growth and repair.
Aldosterone ________.
- A. is secreted by the neurohypophysis
- B. functions to increase sodium reabsorption
- C. presence increases potassium concentration in the blood
- D. production is greatly influenced by ACTH
Correct Answer: B
Rationale: The correct answer is B: Aldosterone functions to increase sodium reabsorption. Aldosterone is a hormone produced by the adrenal glands that acts on the kidneys to enhance the reabsorption of sodium and water and excretion of potassium. This helps regulate blood pressure and electrolyte balance. The other choices are incorrect because: A: Aldosterone is not secreted by the neurohypophysis, but by the adrenal glands. C: Aldosterone actually decreases potassium concentration in the blood. D: Aldosterone production is primarily regulated by the renin-angiotensin-aldosterone system, not greatly influenced by ACTH.
Which of the following is descriptive of the adrenal cortex?
- A. It is the target gland of ACTH.
- B. It secretes catecholamines.
- C. It secretes hormones that lower blood glucose.
- D. It secretes iodine-containing hormones.
Correct Answer: A
Rationale: Step-by-step rationale for why choice A is correct:
1. The adrenal cortex is indeed the target gland of ACTH (Adrenocorticotropic hormone).
2. ACTH stimulates the adrenal cortex to produce and release corticosteroid hormones.
3. These corticosteroid hormones play crucial roles in regulating metabolism, immune response, and stress response.
4. Therefore, choice A accurately describes the relationship between the adrenal cortex and ACTH.
Summary:
Choice A is correct because the adrenal cortex is the target gland of ACTH, not the other choices. The adrenal medulla secretes catecholamines (choice B), hormones that raise blood glucose (not lower, as in choice C), and iodine-containing hormones are secreted by the thyroid gland, not the adrenal cortex (choice D).
Which hormone is responsible for the development of male secondary sexual characteristics?
- A. Androgens
- B. Follicle-stimulating hormone
- C. Epinephrine
- D. Norepinephrine
Correct Answer: A
Rationale: The correct answer is A: Androgens. Androgens, such as testosterone, are responsible for the development of male secondary sexual characteristics, such as facial hair, deep voice, and muscle growth. Follicle-stimulating hormone (B) is involved in sperm production, not male secondary sexual characteristics. Epinephrine (C) and norepinephrine (D) are stress hormones and not related to the development of male secondary sexual characteristics.