Nokea
Which of the following hormones exerts negative feedback control on the secretion of ACTH?
- A. PTH
- B. Glucagon
- C. Cortisol
- D. Corticotrophin-releasing hormone
Correct Answer: C
Rationale: The correct answer is C: Cortisol. Cortisol exerts negative feedback control on the secretion of ACTH by inhibiting the release of corticotrophin-releasing hormone (CRH) and ACTH from the hypothalamus and pituitary gland, respectively. This feedback loop helps regulate the body's stress response and maintain hormone levels within a normal range.
A: PTH (Parathyroid Hormone) does not directly regulate the secretion of ACTH.
B: Glucagon regulates blood sugar levels and does not directly affect ACTH secretion.
D: Corticotrophin-releasing hormone (CRH) is the hormone that stimulates the release of ACTH, so it does not exert negative feedback control on ACTH secretion.
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One of the least complicated of the endocrine control systems directly responds to changing blood levels of ions and nutrients. Which of the following describes this mechanism?
- A. the rapid oxidation of carbohydrates
- B. catabolic inhibition
- C. protein synthesis
- D. humoral stimulation
Correct Answer: D
Rationale: The correct answer is D: humoral stimulation. This mechanism directly responds to changing blood levels of ions and nutrients. Humoral stimulation refers to the regulation of hormone secretion in response to changes in blood levels of various substances like ions and nutrients. It is a feedback mechanism that helps maintain homeostasis by adjusting hormone levels based on the body's needs.
A: Rapid oxidation of carbohydrates is not related to endocrine control systems responding to changing blood levels of ions and nutrients.
B: Catabolic inhibition does not directly respond to changing blood levels of ions and nutrients.
C: Protein synthesis is not a mechanism that directly responds to changing blood levels of ions and nutrients.
Which gland secretes two hormones, one that elevates blood glucose levels and another that decreases blood glucose levels?
- A. Pancreas
- B. Adenohypophysis
- C. Thyroid
- D. Adrenal cortex
Correct Answer: A
Rationale: The correct answer is A: Pancreas. The pancreas secretes insulin to decrease blood glucose levels and glucagon to elevate blood glucose levels. Insulin helps cells absorb glucose for energy, while glucagon triggers the release of stored glucose into the bloodstream. Adenohypophysis (B) secretes various hormones but not related to blood glucose regulation. Thyroid (C) secretes hormones that regulate metabolism, not directly impacting blood glucose levels. Adrenal cortex (D) secretes hormones like cortisol and aldosterone, which are not primarily involved in blood glucose regulation.
The normal endocrine controls can be directly overridden by the __________ system.
- A. nervous
- B. circulatory
- C. digestive
- D. reproductive
Correct Answer: A
Rationale: The correct answer is A: nervous system. The nervous system can directly override normal endocrine controls through the release of neurotransmitters that can stimulate or inhibit hormone release from endocrine glands. The nervous system can rapidly respond to immediate changes in the internal or external environment, allowing for quick adjustments in hormone levels.
Summary of why the other choices are incorrect:
B: The circulatory system is not involved in directly overriding endocrine controls.
C: The digestive system primarily regulates the breakdown and absorption of nutrients, not endocrine controls.
D: The reproductive system is responsible for the production of sex hormones and gametes, but it does not directly override normal endocrine controls.
Which endocrine gland normally produces insulin?
- A. Adrenal
- B. Parathyroid
- C. Pancreas
- D. Liver
Correct Answer: C
Rationale: The correct answer is C: Pancreas. The pancreas is the endocrine gland responsible for producing insulin, which regulates blood sugar levels. It is located behind the stomach and plays a crucial role in maintaining glucose balance in the body. The other choices, A: Adrenal, B: Parathyroid, and D: Liver, do not normally produce insulin. Adrenal glands produce hormones like adrenaline and cortisol, the parathyroid regulates calcium levels, and the liver performs various metabolic functions but does not produce insulin. Therefore, the pancreas is the correct choice for insulin production.
Atropine has the following pharmacological effects EXCEPT:
- A. It increases the heart rate
- B. Stimulates the respiratory center
- C. Has a mydriatic effect
- D. Produces bronchoconstriction
Correct Answer: D
Rationale: The correct answer is D: Atropine does not produce bronchoconstriction. Atropine is an anticholinergic drug that blocks the action of acetylcholine, leading to increased heart rate (A), stimulation of the respiratory center (B), and mydriatic effect (C). Bronchoconstriction is not a pharmacological effect of atropine because it actually helps dilate the bronchi, making it a useful treatment in cases of bronchospasm.