Which of the following is not a steroid-based hormone?
- A. estrogen
- B. aldosterone
- C. epinephrine
- D. cortisone
Correct Answer: C
Rationale: The correct answer is C: epinephrine. Steroid-based hormones are derived from cholesterol and include estrogen, aldosterone, and cortisone. Epinephrine is a catecholamine hormone, not a steroid hormone. Catecholamines are derived from the amino acid tyrosine, not cholesterol like steroid hormones. Therefore, epinephrine does not belong to the category of steroid-based hormones.
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Calcium level in the blood is regulated by the:
- A. Thyroid
- B. Parathyroid
- C. Adrenal medulla
- D. Both A & B
Correct Answer: D
Rationale: The correct answer is D: Both A & B. The thyroid and parathyroid glands work together to regulate calcium levels in the blood. The parathyroid gland releases parathyroid hormone, which increases calcium levels, while the thyroid gland secretes calcitonin, which decreases calcium levels. Therefore, both glands play a crucial role in maintaining calcium homeostasis. Choice A, the thyroid gland, is incorrect as it primarily regulates metabolism. Choice C, the adrenal medulla, is incorrect as it is responsible for releasing adrenaline and noradrenaline, not regulating calcium levels.
Regarding protein metabolism, which statement is CORRECT?
- A. increases the respiratory quotient to values > 1.0
- B. has a specific dynamic action (SDA) of approximately 10%
- C. endogenous protein breakdown is inhibited by glucagon
- D. creatinine excretion is not depressed in starvation
Correct Answer: D
Rationale: The correct answer is D because creatinine excretion is not depressed in starvation. Creatinine is a byproduct of muscle metabolism and is relatively constant even during starvation when muscle breakdown occurs. A: Incorrect, as increasing respiratory quotient > 1.0 indicates excessive carbohydrate utilization. B: Incorrect, SDA is the energy used for digestion and absorption of nutrients, not specific to protein metabolism. C: Incorrect, glucagon stimulates protein breakdown to release amino acids for energy during fasting.
Which of the following is not a category of endocrine gland stimulus?
- A. enzyme
- B. humoral
- C. neural
- D. hormonal
Correct Answer: A
Rationale: The correct answer is A: enzyme. Endocrine glands are stimulated by three main categories: humoral (based on blood levels of certain substances), neural (stimulation by nerves), and hormonal (stimulation by other hormones). Enzymes do not directly stimulate endocrine glands. They are biological catalysts that facilitate biochemical reactions, not a category of stimulus for endocrine glands. Therefore, A is the correct answer. Choices B, C, and D are incorrect as they are valid categories of endocrine gland stimulus based on blood levels, nerves, and hormones respectively.
Which of the following is NOT a type of hormone stimulus?
- A. hormonal stimulus
- B. humoral stimulus
- C. neural stimulus
- D. receptor-mediated stimulus
Correct Answer: D
Rationale: The correct answer is D, receptor-mediated stimulus. Hormones can be stimulated by hormonal, humoral, or neural factors, but not directly by receptors. Hormonal stimulus involves other hormones triggering hormone release, humoral stimulus involves changing blood levels of ions or nutrients triggering hormone release, and neural stimulus involves direct nerve stimulation triggering hormone release. Receptor-mediated stimulus is not a recognized type of hormone stimulus because hormones do not directly respond to receptors in this context.
Insulin, a small (51-amino-acid) protein, is synthesized by the beta cells of the pancreas. This hormone is released ________.
- A. in excessive amounts in obese people
- B. in response to severe physical stress (i.e., a ten-mile run)
- C. when the bodyʹs glucose level rises
- D. when the bodyʹs glucose level drops
Correct Answer: C
Rationale: The correct answer is C because insulin is released when the body's glucose level rises. This is a key function of insulin to regulate blood sugar levels. When glucose levels increase after a meal, beta cells release insulin to help cells absorb and use glucose for energy. This process helps to maintain blood sugar within a healthy range.
Choice A is incorrect because insulin release is not necessarily excessive in obese people, but rather it can be impaired due to insulin resistance. Choice B is incorrect because insulin is typically released in response to high blood sugar levels, not physical stress. Choice D is incorrect because insulin is released when blood sugar levels drop too low, not rise.