Steroid hormones:
- A. require a second messenger.
- B. are secreted by the adrenal cortex.
- C. are secreted by the posterior pituitary.
- D. are secreted by the pancreas.
Correct Answer: B
Rationale: The correct answer is B: Steroid hormones are secreted by the adrenal cortex. The adrenal cortex is responsible for producing steroid hormones such as cortisol, aldosterone, and sex hormones. This is supported by the understanding of endocrine gland functions. Choices A, C, and D are incorrect because steroid hormones do not require a second messenger, are not secreted by the posterior pituitary, and are not secreted by the pancreas. Understanding the specific glands and their hormone production is crucial in selecting the correct answer.
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Thyroid hormone (a small iodinated amine) enters target cells in a manner similar to ________.
- A. insulin, because insulin is a small peptide
- B. steroid hormones, because both diffuse easily into target cells
- C. growth hormone, because the thyroid works synergistically with thyroid hormone
- D. glucagon, because the structure of glucagon is similar to that of thyroid hormone
Correct Answer: B
Rationale: The correct answer is B: steroid hormones, because both diffuse easily into target cells. Thyroid hormone, being a small iodinated amine, can easily pass through the cell membrane and bind to intracellular receptors, similar to steroid hormones. Unlike insulin (choice A), which binds to cell surface receptors, thyroid hormone and steroid hormones enter the cell to exert their effects. Growth hormone (choice C) and glucagon (choice D) do not share the same mechanism of entry into target cells as thyroid hormone, making them incorrect choices.
Oxytocin ________.
- A. release is an example of a positive feedback control mechanism
- B. is an adenohypophyseal secretion
- C. exerts its most important effects during menstruation
- D. controls milk production
Correct Answer: A
Rationale: The correct answer is A because oxytocin release is an example of a positive feedback control mechanism. When oxytocin is released during childbirth, it stimulates contractions, which in turn lead to more oxytocin release, creating a positive feedback loop. This helps in the progression of labor.
Choice B is incorrect because oxytocin is a neurohypophyseal hormone, not an adenohypophyseal secretion. Choice C is incorrect as oxytocin's main effects are related to labor, delivery, and lactation, not menstruation. Choice D is incorrect because oxytocin primarily controls uterine contractions during labor and milk ejection during breastfeeding, not milk production itself.
The endocrine system works together with the ________ system to maintain the body’s equilibrium?
- A. digestive system
- B. nervous system
- C. respiratory system
- D. reproductive system
Correct Answer: B
Rationale: The correct answer is B: nervous system. The endocrine system and nervous system work together in maintaining the body's equilibrium through communication and regulation of bodily functions. The nervous system controls rapid responses, while the endocrine system regulates slower, long-term responses through hormones. The digestive system (A) primarily focuses on breaking down food and absorbing nutrients. The respiratory system (C) is responsible for gas exchange. The reproductive system (D) is involved in reproduction and hormone production, but not in maintaining the body's equilibrium.
The nurse reviews the function of thyroid gland hormones. What is the primary function of calcitonin?
- A. Sodium and potassium balance
- B. Magnesium balance
- C. Norepinephrine balance
- D. Calcium and phosphorus balance
Correct Answer: D
Rationale: The primary function of calcitonin is to regulate calcium and phosphorus balance in the body. Calcitonin works to decrease blood calcium levels by inhibiting bone breakdown and increasing calcium excretion by the kidneys. This helps maintain the overall balance of calcium and phosphorus in the body. Choices A, B, and C are incorrect as they do not align with the known function of calcitonin. Sodium and potassium balance, magnesium balance, and norepinephrine balance are not directly influenced by calcitonin.
Regulating hormones from the hypothalamus ________.
- A. enter venous circulation and travel to the heart, which pumps the hormone-containing blood to the pituitary
- B. enter the hepatic portal system, which feeds the pituitary
- C. travel by arteries to the pituitary
- D. first enter into the hypophyseal portal system
Correct Answer: D
Rationale: The correct answer is D because hormones from the hypothalamus first enter the hypophyseal portal system before reaching the pituitary gland. This system allows direct communication between the hypothalamus and the pituitary gland, enabling precise control over hormone release. Choices A, B, and C are incorrect because they do not accurately describe the normal pathway of hormone regulation from the hypothalamus to the pituitary gland. Option A is incorrect as hormones do not travel to the heart before reaching the pituitary. Option B is incorrect because hormones do not enter the hepatic portal system to reach the pituitary. Option C is incorrect as hormones do not travel to the pituitary through arteries.