Which endocrine gland is known as the master gland?
- A. Adrenal
- B. Liver
- C. Pancreas
- D. Pituitary
Correct Answer: D
Rationale: The correct answer is D: Pituitary gland. The pituitary gland is known as the master gland because it controls the functions of other endocrine glands in the body by secreting various hormones that regulate growth, reproduction, metabolism, and other essential bodily functions. It is located at the base of the brain and plays a crucial role in maintaining hormonal balance.
Explanation for other choices:
A: Adrenal gland primarily regulates stress response and metabolism.
B: Liver is not an endocrine gland; it is involved in metabolism and detoxification.
C: Pancreas is responsible for regulating blood sugar levels through insulin and glucagon secretion but is not known as the master gland.
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Your patient is diagnosed with myasthenia gravis, and she is given a prescription for pyridostigmine. Which of the following best summarizes the drug’s mechanism of action?
- A. Blocks muscarinic receptors, so that acetylcholine preferentially stimulates skeletal muscle
- B. Inhibits reuptake of acetylcholine by motor nerves
- C. Inhibits skeletal muscle activation at rest so that the muscles are less susceptible to fatigue during exercise
- D. Inhibits breakdown of acetylcholine, thereby improving activation of skeletal muscle by acetylcholine
Correct Answer: D
Rationale: The correct answer is D: "Inhibits breakdown of acetylcholine, thereby improving activation of skeletal muscle by acetylcholine."
Rationale:
1. Pyridostigmine is an acetylcholinesterase inhibitor, which means it blocks the breakdown of acetylcholine.
2. In myasthenia gravis, there is a decrease in acetylcholine receptor sites, leading to muscle weakness.
3. By inhibiting the breakdown of acetylcholine, pyridostigmine increases the availability of acetylcholine at the neuromuscular junction, improving muscle activation.
4. This mechanism helps alleviate muscle weakness in myasthenia gravis patients.
Summary:
A: Incorrect. Pyridostigmine does not block muscarinic receptors or change the preference of acetylcholine stimulation.
B: Incorrect. Pyridostigmine does not inhibit reuptake of acetylcholine; it acts by inhibiting its breakdown
Androgens are produced by the _______.
- A. ovaries.
- B. testes.
- C. hypothalamus.
- D. islets of Langerhans.
Correct Answer: B
Rationale: The correct answer is B: testes. Androgens, such as testosterone, are male sex hormones primarily produced by the testes. The testes contain specialized cells called Leydig cells that secrete androgens. Ovaries (A) produce female sex hormones like estrogen and progesterone. The hypothalamus (C) regulates hormone production through the pituitary gland but does not directly produce androgens. Islets of Langerhans (D) are clusters of cells in the pancreas responsible for producing insulin and glucagon, not androgens.
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.
Which two elements react together to form an ionic compound?
- A. R and T
- B. T and X
- C. X and Z
- D. Z and R
Correct Answer: C
Rationale: The correct answer is C, X and Z. Ionic compounds are formed when a metal (X) reacts with a nonmetal (Z) by transferring electrons to achieve a stable octet configuration. Metal atoms tend to lose electrons to form positively charged cations, while nonmetal atoms tend to gain electrons to form negatively charged anions. In this case, X (metal) and Z (nonmetal) will react to form an ionic compound through electron transfer. Choices A, B, and D are incorrect because they do not involve a metal-nonmetal combination, which is essential for the formation of an ionic compound.
Which is NOT part of the normal content of gastric juice?
- A. HPO42-
- B. mucus
- C. lipase
- D. amylase
Correct Answer: D
Rationale: The correct answer is D: amylase. Gastric juice primarily consists of hydrochloric acid, pepsin, and mucus. Amylase is an enzyme produced in the pancreas, not in the stomach. It functions in the small intestine to break down carbohydrates. Therefore, amylase is not a normal component of gastric juice. Choices A, B, and C are incorrect because HPO42- (phosphate ions), mucus, and lipase are all typically found in gastric juice.