Nokea
Most endocrine secretions are controlled by _____.
- A. positive feedback.
- B. negative feedback.
- C. neural feedback.
Correct Answer: B
Rationale: Step 1: Negative feedback is the primary mechanism in endocrine system regulation to maintain homeostasis.
Step 2: When hormone levels reach a certain set point, negative feedback signals the gland to stop producing that hormone.
Step 3: This ensures that hormone levels remain within a specific range.
Step 4: Positive feedback would lead to further hormone secretion, disrupting homeostasis.
Step 5: Neural feedback is not a common mechanism for regulating endocrine secretions.
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____________ is a steroid hormone.
- A. Vitamin D
- B. Epinephrine
- C. Insulin
- D. all of these
Correct Answer: A
Rationale: Vitamin D is the correct answer as it is a steroid hormone synthesized from cholesterol. Steroid hormones are derived from cholesterol and have a similar chemical structure. Epinephrine and Insulin are not steroid hormones. Epinephrine is a catecholamine produced by the adrenal glands, and Insulin is a peptide hormone produced by the pancreas. Choice D is incorrect as not all options listed are steroid hormones.
The posterior pituitary gland stores and secretes
- A. oxytocin and antidiuretic hormone
- B. human growth hormone and thyroid stimulating hormone
- C. prolactin and follicle stimulating hormone
- D. glucocorticoids and androgens
Correct Answer: A
Rationale: Step-by-step rationale:
1. The posterior pituitary gland stores oxytocin and antidiuretic hormone (ADH).
2. Oxytocin is responsible for uterine contractions and milk ejection.
3. ADH regulates water balance by controlling urine concentration.
4. These hormones are produced in the hypothalamus and released from the posterior pituitary.
5. Choice A is correct as it accurately identifies the hormones stored and secreted by the posterior pituitary.
Summary:
- Choice B is incorrect because human growth hormone and thyroid stimulating hormone are not stored or secreted by the posterior pituitary.
- Choice C is incorrect because prolactin and follicle stimulating hormone are produced by the anterior pituitary.
- Choice D is incorrect because glucocorticoids and androgens are not stored or secreted by the posterior pituitary.
Which is NOT an action of CCK?
- A. gallbladder contraction
- B. increased gastric motility and emptying
- C. glucagon secretion
- D. secretion of pancreatic juice
Correct Answer: B
Rationale: The correct answer is B: increased gastric motility and emptying. CCK, or cholecystokinin, is a hormone released by the small intestine in response to the presence of fats. Its main actions include stimulating gallbladder contraction (A) to release bile for fat digestion, triggering the secretion of pancreatic juice (D) containing digestive enzymes, and inhibiting gastric motility and emptying. Therefore, increased gastric motility and emptying (choice B) is NOT an action of CCK. This is because CCK acts to slow down gastric emptying to allow for effective digestion of fats in the small intestine. Choices A, C, and D are all correct actions of CCK based on its role in the digestive process.
Adrenaline can be used in the following EXCEPT:
- A. Allergic reactions
- B. Acute bronchial asthma
- C. Complete heart block
- D. Angina pectoris
Correct Answer: D
Rationale: Adrenaline is a sympathomimetic drug that acts on adrenergic receptors. In acute situations like allergic reactions, bronchial asthma, and heart block, adrenaline can be beneficial due to its bronchodilator and vasoconstrictor effects. However, in angina pectoris, which is caused by reduced blood flow to the heart muscle, the vasoconstrictor effect of adrenaline can worsen the condition by increasing the workload of the heart. Therefore, adrenaline should not be used in angina pectoris.
The most appropriate drug for treating myasthenia gravis is:
- A. Neostigmine
- B. Pilocarpine
- C. Succinylcholine
- D. Tubocurarine
Correct Answer: A
Rationale: Neostigmine is the correct choice for treating myasthenia gravis as it is an acetylcholinesterase inhibitor that increases acetylcholine levels, improving muscle strength. Pilocarpine is a muscarinic agonist used for glaucoma. Succinylcholine is a depolarizing neuromuscular blocker used for intubation. Tubocurarine is a non-depolarizing neuromuscular blocker.