Nokea
Underproduction of growth hormone during the growing years produces ______.
- A. myxedema.
- B. gigantism.
- C. pituitary dwarfism.
- D. acromegaly.
Correct Answer: C
Rationale: The correct answer is C: pituitary dwarfism. Growth hormone deficiency during growing years results in pituitary dwarfism due to stunted growth. Myxedema (choice A) is associated with hypothyroidism, not growth hormone deficiency. Gigantism (choice B) occurs due to excessive growth hormone production in childhood. Acromegaly (choice D) is caused by excess growth hormone in adulthood, not during the growing years. Thus, choice C is the most appropriate based on the impact of growth hormone deficiency on growth during childhood.
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A patient has been receiving a large dose of prednisone for the relief of arthritic pain for 6 months. He suddenly stops taking his medication. What is the most serious concern?
- A. His arthritic pain will recur.
- B. He will develop an acute adrenal insufficiency.
- C. He will continue to exhibit symptoms of Cushing syndrome.
- D. He will develop a moon face and buffalo hump.
Correct Answer: B
Rationale: The correct answer is B: He will develop an acute adrenal insufficiency. When a patient abruptly stops taking a large dose of prednisone after long-term use, it can suppress the body's natural production of cortisol. This sudden withdrawal can lead to adrenal insufficiency, a potentially life-threatening condition. The adrenal glands may not be able to produce enough cortisol to meet the body's needs, causing symptoms such as fatigue, weakness, low blood pressure, and even shock. This is a serious concern that requires medical attention.
Incorrect choices:
A: His arthritic pain will recur - While this is a valid concern, it is not the most serious issue compared to acute adrenal insufficiency.
C: He will continue to exhibit symptoms of Cushing syndrome - Cushing syndrome is a result of prolonged exposure to high levels of cortisol, not sudden withdrawal.
D: He will develop a moon face and buffalo hump - These are physical symptoms associated with Cushing syndrome, not acute adrenal
A 33-year-old woman becomes poisoned after receiving an injection of concentrated botulinum toxin. Which of the following is the main neurochemical mechanism by which this Clostridium toxin causes its effects?
- A. Directly activates all muscarinic and nicotinic receptors
- B. Inhibits ACh release from all cholinergic nerves
- C. Prevents neuronal norepinephrine reuptake
- D. Releases norepinephrine via a nonexocytotic process
Correct Answer: B
Rationale: The correct answer is B: Inhibits ACh release from all cholinergic nerves. Botulinum toxin blocks the release of acetylcholine (ACh) from cholinergic nerve terminals, leading to muscle paralysis. This occurs through the cleavage of SNARE proteins, preventing vesicle fusion and neurotransmitter release. Choice A is incorrect because botulinum toxin does not directly activate receptors. Choice C is incorrect as botulinum toxin does not affect neuronal norepinephrine reuptake. Choice D is incorrect because botulinum toxin does not release norepinephrine via a nonexocytotic process.
A patient presents with a moon face, truncal obesity, hypertension, purple straiae, buffalo hump, fragile skin and impaired glucose tolerance. The opposite of the current increased levels of the prime hormone involved in this patient is seen in:
- A. Addison's disease
- B. Pheochromocytoma
- C. Hyperaldosteronism
- D. Cushing's syndrome
Correct Answer: A
Rationale: Step 1: Identify the symptoms described in the patient: Moon face, truncal obesity, hypertension, purple striae, buffalo hump, fragile skin, impaired glucose tolerance.
Step 2: These symptoms are classic for Cushing's syndrome, which is caused by excess cortisol.
Step 3: The opposite of increased cortisol levels is decreased cortisol levels.
Step 4: Addison's disease is characterized by adrenal insufficiency, leading to decreased cortisol levels.
Step 5: Therefore, the correct answer is A: Addison's disease.
Summary:
- B: Pheochromocytoma is a tumor of the adrenal medulla, causing excess catecholamines, not related to cortisol.
- C: Hyperaldosteronism is excess aldosterone production, not related to cortisol.
- D: Cushing's syndrome is characterized by excess cortisol, not the opposite.
Insulin and glucagon:
- A. are secreted by the beta cells of the islets of Langerhans.
- B. elevate blood glucose levels.
- C. are secreted in response to declining plasma levels of glucose.
- D. are secreted by the pancreas to regulate blood glucose.
Correct Answer: D
Rationale: The correct answer is D because insulin and glucagon are both hormones secreted by the pancreas to regulate blood glucose levels. Insulin is secreted by beta cells in response to high blood glucose levels, promoting glucose uptake by cells. Glucagon is secreted by alpha cells in response to low blood glucose levels, stimulating the release of stored glucose. Choices A and C are incorrect because insulin is secreted by beta cells, not glucagon, and they are secreted in response to high, not low, glucose levels. Choice B is incorrect because insulin lowers blood glucose levels, while glucagon raises them.
Which term describes the maintenance of a stable internal environment?
- A. negative feedback
- B. positive feedback
- C. homeostasis
- D. metabolism
Correct Answer: C
Rationale: Homeostasis is the maintenance of a stable internal environment to support optimal physiological functioning. It involves mechanisms that regulate variables within a narrow range. Negative feedback is a key mechanism in maintaining homeostasis by counteracting deviations from set points. Positive feedback amplifies changes and is not involved in maintaining stability. Metabolism refers to the chemical processes in the body and is not specifically related to the maintenance of internal stability. Therefore, the correct answer is C (homeostasis) because it directly relates to the concept of maintaining a stable internal environment through regulatory mechanisms.