Leptin is secreted by ________.

Correct Answer: B

Rationale: Leptin is primarily secreted by adipocytes, which are fat cells. Adipocytes play a crucial role in regulating energy balance and appetite through leptin secretion. Lymphocytes are immune cells, goblet cells secrete mucus, and fibroblasts are connective tissue cells, none of which are involved in leptin secretion.

Correct Answer: D

Rationale: The correct answer is D: steroid. Steroid hormones are lipid-soluble and can pass through cell membranes easily. This property allows them to be taken orally since they are not digested in the stomach and can be absorbed in the intestines. Carbohydrates (A), peptides (B), and proteins (C) are water-soluble and cannot pass through cell membranes easily, making them unsuitable for oral administration.

Correct Answer: C

Rationale: Rationale: 1. Oxytocin is the hormone responsible for stimulating uterine contractions during labor and delivery. 2. Oxytocin also triggers the release of milk during nursing by causing contraction of the cells around the milk-filled alveoli. 3. ADH (A) regulates water balance, glucagon (B) regulates blood sugar levels, and prolactin (D) stimulates milk production but not milk release. Summary: Oxytocin is the correct answer because it specifically stimulates uterine contractions and milk release during nursing, while the other choices are not directly related to these functions.

Correct Answer: A

Rationale: Step-by-step rationale: 1. Exophthalmic goiter refers to bulging eyes and enlarged thyroid gland. 2. Graves disease is an autoimmune disorder causing hyperthyroidism, resulting in both symptoms. 3. Hashimoto's disease is an autoimmune disorder causing hypothyroidism, not associated with exophthalmic goiter. 4. Myxedema is severe hypothyroidism but does not typically present with exophthalmic goiter. 5. Acromegaly is caused by excess growth hormone, leading to enlarged hands and feet, not related to exophthalmic goiter.

Correct Answer: A

Rationale: The correct answer is A: Addison disease. Hyposecretion of adrenal cortex hormones can lead to Addison disease, characterized by fatigue, weight loss, low blood pressure, and skin discoloration. This is because insufficient cortisol and aldosterone production from the adrenal cortex can disrupt the body's stress response and electrolyte balance. Summary of why other choices are incorrect: B: Diabetes mellitus is primarily related to insulin regulation issues, not adrenal cortex hormones. C: Cushing syndrome is caused by hypersecretion, not hyposecretion, of adrenal cortex hormones. D: Cretinism is associated with thyroid hormone deficiency, not adrenal cortex hormone deficiency.