Which of the following is a protein hormone?

Correct Answer: B

Rationale: The correct answer is B: Insulin. Insulin is a protein hormone produced by the pancreas that regulates blood sugar levels. Proteins are large molecules made up of amino acids, and insulin fits this definition. Oxytocin (A) is a peptide hormone, not a protein. TSH (C) and ADH (D) are both peptide hormones as well, not proteins. In summary, insulin is the only option that fits the criteria of being a protein hormone.

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: A

Rationale: The pituitary gland is often referred to as the 'master gland' because it plays a crucial role in regulating other endocrine glands in the body. It secretes hormones that control various bodily functions, such as growth, reproduction, and metabolism. The other choices, thyroid, thymus, and hypothalamus, are important glands as well, but they do not have the same broad control over the endocrine system as the pituitary gland. The thyroid regulates metabolism, thymus is involved in immune function, and hypothalamus regulates body temperature, hunger, and thirst. However, none of these glands have the overall regulatory function and influence on other glands as the pituitary gland does.

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.