A patient presents with weight loss, polyphagia, polydypsia, increased tiredness, vomiting, and hyperventilation. He is young and his parents are also diagnosed with the same disease. Which of the following is the most common etiological factor associated with this disease seen in older populations?

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: 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.

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.

Correct Answer: D

Rationale: The correct answer is D: hormones. Hormones are chemical substances secreted by cells into extracellular fluids to regulate metabolic functions in other cells. They act as messengers, traveling through the bloodstream to target tissues. Enzymes (A) are catalysts that accelerate chemical reactions. Antibodies (B) are proteins produced by the immune system to neutralize pathogens. Proteins (C) are essential macromolecules for various cellular functions but do not specifically regulate metabolic functions in other cells like hormones do.