Nokea
Concerning Alpha blockers, which of the following is CORRECT:
- A. Phentolamine is a selective Alpha1 blocker
- B. Alpha2 blockers decrease noradrenaline release
- C. Prazosin can block Alpha1 receptor only
- D. They decrease both BP and HR
Correct Answer: C
Rationale: Rationale:
C: Prazosin can block Alpha1 receptor only.
- Prazosin is a selective Alpha1 blocker, mainly used for hypertension.
- By blocking Alpha1 receptors, it reduces vasoconstriction and lowers blood pressure.
- Prazosin does not affect Alpha2 receptors, distinguishing it from non-selective Alpha blockers.
- Correct as it accurately describes Prazosin's mechanism of action.
Incorrect:
A: Phentolamine is a non-selective Alpha blocker, affecting both Alpha1 and Alpha2 receptors.
B: Alpha2 blockers increase noradrenaline release by inhibiting the negative feedback control.
D: Alpha blockers typically decrease blood pressure, but can increase heart rate due to vasodilation.
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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.
Which of the following elements is required for the synthesis of thyroid hormone?
- A. copper
- B. iodine
- C. sulfur
- D. zinc
Correct Answer: B
Rationale: The correct answer is B: iodine. Iodine is an essential element required for the synthesis of thyroid hormone. Thyroid hormones such as thyroxine (T4) and triiodothyronine (T3) contain iodine atoms. Without sufficient iodine, the thyroid gland cannot produce these hormones, leading to thyroid disorders like hypothyroidism or goiter. Copper (A), sulfur (C), and zinc (D) are not directly involved in the synthesis of thyroid hormone. Copper is important for enzyme function, sulfur is present in amino acids, and zinc is involved in various cellular processes but not specifically in thyroid hormone synthesis.
Name the structure that prevents food from entering the lungs?
- A. Pyloric sphincter
- B. Trachea
- C. Pharynx
- D. Epiglottis
Correct Answer: D
Rationale: The correct answer is D: Epiglottis. The epiglottis is a flap of tissue that covers the trachea during swallowing, preventing food from entering the lungs. When food is swallowed, the epiglottis closes off the trachea to ensure that the food goes down the esophagus into the stomach.
Incorrect choices:
A: The pyloric sphincter is a valve located between the stomach and the small intestine, regulating the flow of partially digested food.
B: The trachea is the windpipe that connects the larynx to the bronchi, allowing air to pass into the lungs.
C: The pharynx is the throat area where the pathways for both food and air cross, but it is the epiglottis that specifically prevents food from entering the lungs.
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.
Pilocarpine is used in the treatment of:
- A. Heart failure
- B. Bronchial asthma
- C. Urinary obstruction
- D. Glaucoma
Correct Answer: D
Rationale: Pilocarpine is a parasympathomimetic agent that stimulates the muscarinic receptors in the eye, causing pupillary constriction and reducing intraocular pressure. This mechanism of action makes it effective in treating glaucoma. Heart failure (A), bronchial asthma (B), and urinary obstruction (C) are not indications for pilocarpine use based on its pharmacological properties and effects.