Nokea
Which of the following is the most potent stimulus for hypothalamic production of arginine vasopressin?
- A. Hypertonicity
- B. Hyperkalemia
- C. Hypokalemia
- D. Hypotonicity
Correct Answer: A
Rationale: Hypertonicity (increased osmolarity or high concentration of solutes in the blood) is the most potent stimulus for the hypothalamic production of arginine vasopressin (also known as antidiuretic hormone or ADH). When the body senses increased plasma osmolality, the osmoreceptors in the hypothalamus stimulate the release of vasopressin from the posterior pituitary gland. Vasopressin acts on the kidneys to increase water reabsorption and decrease urine output, helping to restore normal osmolarity. This mechanism helps to conserve water and maintain body fluid balance in response to dehydration or increased solute concentration in the blood.
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Which of the following does the adrenal cortex produce?
- A. Adrenaline
- B. Aldosterone
- C. Cortisol
- D. Noradrenaline
Correct Answer: B
Rationale: The adrenal cortex is the outer region of the adrenal glands and is responsible for producing several hormones, including aldosterone. Aldosterone is a mineralocorticoid hormone that plays a crucial role in regulating electrolyte balance, particularly sodium and potassium, in the body. It helps maintain blood pressure and fluid balance by acting on the kidneys to reabsorb sodium and water while excreting potassium in the urine. Adrenaline and noradrenaline (also known as epinephrine and norepinephrine) are produced by the adrenal medulla, which is the inner region of the adrenal glands. Cortisol is another hormone produced by the adrenal cortex, but aldosterone specifically regulates electrolyte balance.
Acromegaly is associated with all of the following except:
- A. Acanthosis nigricans
- B. Fibromata mollusca
- C. Micrognathia
- D. Cardiomegaly
Correct Answer: C
Rationale: Acromegaly is a disorder caused by excessive growth hormone production after the closure of the epiphyses (growth plates) in bones, leading to abnormal growth of tissues and organs. The following options are associated with acromegaly:
A person with acromegaly usually has:
- A. prognathism and large fleshy lips.
- B. hypoglycemia.
- C. a growth hormone deficiency.
- D. protruding eye balls.
Correct Answer: A
Rationale: Acromegaly is a hormonal disorder that results from the overproduction of growth hormone (GH) in adulthood. One of the key physical characteristics associated with acromegaly is the enlargement of facial features. People with acromegaly often develop prognathism, which is a condition where the lower jaw protrudes forward, leading to a prominent lower face. Additionally, they may have large fleshy lips due to the soft tissue swelling that occurs as a result of excess GH. Other common signs of acromegaly include enlarged hands and feet, thickened skin, and joint pain.
All of the following represent examples of hypothalamic-pituitary negative feedback except:
- A. Cortisol on the CRH-ACTH axis
- B. Gonadal steroids on the GnRH-LH/FSH axis
- C. IGF-1 on the growth hormone-releasing hormone (GHRH)-GH axis
- D. Renin-angiotensin-aldosterone axis
Correct Answer: D
Rationale: The renin-angiotensin-aldosterone axis does not involve the hypothalamus or pituitary gland; instead, it primarily involves the kidneys and the renin-secreting cells. In this axis, renin is released in response to low blood pressure, leading to the formation of angiotensin II and the subsequent release of aldosterone from the adrenal glands. Feedback mechanisms for this axis primarily involve the regulation of renin release based on blood pressure rather than involving direct negative feedback from downstream hormones on the hypothalamus or pituitary gland. On the other hand, choices A, B, and C all involve classic examples of hypothalamic-pituitary negative feedback loops where the end hormone suppresses the release of the stimulating hormones at the hypothalamic and pituitary levels.
Which one of the following statements is true regarding the prevalence of acromegaly?
- A. Acromegaly affects a similar number of men and women
- B. Acromegaly affects twice as many women than men
- C. Acromegaly affects twice as many men than it does women
Correct Answer: C
Rationale: Acromegaly is a rare hormonal disorder where excess growth hormone is produced, leading to the enlargement of bones and tissues. The prevalence of acromegaly is higher in men compared to women, with a ratio of about two men affected for every woman. This gender difference is believed to be due to the impact of sex hormones on the development and progression of the condition. While acromegaly can affect both men and women, men are more commonly diagnosed with the disorder.