Nokea
Hypertensive effect of adrenaline is reversed by:
- A. Propranolol
- B. Phenylephrine
- C. Prazosin
- D. Amphetamine
Correct Answer: C
Rationale: Step-by-step rationale:
1. Adrenaline causes vasoconstriction leading to increased blood pressure.
2. Prazosin is an alpha-1 adrenergic receptor antagonist.
3. By blocking alpha-1 receptors, prazosin reverses the vasoconstrictive effects of adrenaline.
4. Propranolol (A) is a non-selective beta-blocker and would not directly counteract adrenaline's vasoconstrictive effects.
5. Phenylephrine (B) is a vasoconstrictor itself and would further exacerbate the hypertensive effect of adrenaline.
6. Amphetamine (D) is a sympathomimetic drug that would also enhance the hypertensive effects of adrenaline.
Summary:
Prazosin (C) is the correct answer as it specifically targets the alpha-1 adrenergic receptors responsible for the hypertensive effects of adrenaline. Propranolol, phenylephrine, and amphetamine would
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Which of the following is not a change that may be caused by hormonal stimulus?
- A. a change in membrane potential
- B. the stimulation of a genetic event resulting in protein synthesis
- C. an increase in enzymatic activity
- D. direct control of the nervous system
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.
Dopamine and homovanillic acid are secreted in ______________.
- A. Neuroblastoma
- B. Adenoma
- C. Pheochromocytoma
Correct Answer: A
Rationale: Step-by-step rationale:
1. Dopamine and homovanillic acid are neurotransmitters.
2. Neuroblastoma is a type of cancer that originates in neuroblasts, which are immature nerve cells.
3. Neuroblastoma can produce neurotransmitters like dopamine and homovanillic acid.
4. Therefore, dopamine and homovanillic acid are secreted in neuroblastoma.
Summary:
- Choice A is correct as neuroblastoma can secrete dopamine and homovanillic acid.
- Choices B and C are incorrect as they are unrelated to the secretion of these neurotransmitters.
Which of the following is descriptive of prolactin?
- A. Secreted by the posterior pituitary gland.
- B. Also called lactogenic hormone.
- C. Causes the milk let-down reflex.
- D. Stimulates the neurohypophysis to synthesize oxytocin.
Correct Answer: B
Rationale: Step-by-step rationale:
1. Prolactin is also called lactogenic hormone, as it promotes milk production in the mammary glands.
2. Secreted by the anterior pituitary gland, not the posterior pituitary gland.
3. Milk let-down reflex is primarily controlled by oxytocin, not prolactin.
4. Prolactin does not stimulate the neurohypophysis (posterior pituitary) to synthesize oxytocin.
Summary:
Choice B is correct because it accurately describes the function of prolactin in promoting lactation. Choices A, C, and D are incorrect due to inaccuracies in the functions and secretion of prolactin.
Identify the growth factor that is released by cancer cells to create a capillary network that aids the cancer growth.
- A. macrophage colony-stimulating factor
- B. platelet derived growth factor
- C. tumor angiogenesis factor
- D. epidermal growth factor
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.
Which of the following is NOT a mechanism of hormone action?
- A. plasma membrane permeability changes
- B. cellular mutations occur
- C. enzymes are activated or inactivated
- D. mitosis is stimulated
Correct Answer: B
Rationale: The correct answer is B: cellular mutations occur. Hormones typically act through binding to specific receptors on target cells to initiate a signaling cascade. This process does not involve inducing mutations in the cell's DNA. Plasma membrane permeability changes, enzyme activation/inactivation, and stimulation of mitosis are all well-established mechanisms of hormone action. Therefore, B is the correct answer as it does not align with the usual mechanisms by which hormones exert their effects.