Which of the following is a symptom of Addison’s disease?

Correct Answer: C

Rationale: The correct answer is C: Hyperpigmentation. Addison's disease is a condition characterized by adrenal insufficiency, leading to decreased production of cortisol and aldosterone. Hyperpigmentation is a common symptom due to elevated levels of ACTH stimulating melanin production. Other choices are incorrect because Addison's disease typically presents with hypotension, weight loss, and bradycardia, rather than hypertension, weight gain, or tachycardia.

Correct Answer: B

Rationale: The correct answer is B: Obesity. In the given case, the patient most likely has type 1 diabetes, which commonly presents with the symptoms described. The genetic predisposition mentioned (parents diagnosed) also suggests type 1 diabetes. Obesity is a well-known risk factor for type 2 diabetes, which is more common in older populations. Therefore, the most common etiological factor associated with diabetes in older populations is obesity. A: Smoking is a risk factor for various diseases, but not typically associated with diabetes. C: Hypertension is a common comorbidity with diabetes, but not a direct etiological factor. D: Infections can sometimes trigger type 1 diabetes, but it is not the most common etiological factor associated with the disease in older populations.

Correct Answer: D

Rationale: The correct answer is D: Aldosterone. Aldosterone directly influences the reabsorption of sodium in the kidney tubules, leading to increased Na+ excretion. Progesterone (A) does not have a significant effect on Na+ excretion. Cortisol (B) mainly affects glucose metabolism and has minimal impact on Na+ excretion. Vasopressin (C) primarily regulates water reabsorption, not Na+ excretion. Therefore, Aldosterone has the greatest effect on Na+ excretion due to its specific role in sodium reabsorption in the kidneys.

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.

Correct Answer: A

Rationale: The correct answer is A: negative feedback mechanisms. Negative feedback mechanisms are essential in regulating hormone levels within a narrow range to maintain homeostasis. When hormone levels rise, negative feedback mechanisms signal the body to decrease production, and vice versa. Positive feedback mechanisms amplify hormone production, not regulate it. Hormone-receptor complexes and hormone-gene complexes are important for hormone actions but do not regulate the overall endocrine system.