Nokea
Hypersecretion of antidiuretic hormone (ADH) can occur in all of the following situations EXCEPT __________.
- A. damage to the pineal gland
- B. after neurosurgery
- C. after general anesthesia
- D. ectopic ADH secretion by pulmonary cancer
Correct Answer: A
Rationale: The correct answer is A: damage to the pineal gland. The pineal gland does not regulate ADH secretion; it primarily produces melatonin. Neurosurgery and general anesthesia may disrupt the feedback mechanisms controlling ADH release. Ectopic ADH secretion by pulmonary cancer can lead to excessive ADH production. The key is to identify a situation where ADH hypersecretion is less likely to occur due to the gland's function.
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Which of the following is NOT a mechanism of hormone action?
- A. plasma membrane permeability changes
- B. cellular mutations occur
- C. enzymes are activated or inactivated
- D. mitosis is stimulated
Correct Answer: B
Rationale: The correct answer is B: cellular mutations occur. Hormones typically act through binding to specific receptors on target cells to initiate a signaling cascade. This process does not involve inducing mutations in the cell's DNA. Plasma membrane permeability changes, enzyme activation/inactivation, and stimulation of mitosis are all well-established mechanisms of hormone action. Therefore, B is the correct answer as it does not align with the usual mechanisms by which hormones exert their effects.
Name the structure that prevents food from entering the lungs?
- A. Pyloric sphincter
- B. Trachea
- C. Pharynx
- D. Epiglottis
Correct Answer: D
Rationale: The correct answer is D: Epiglottis. The epiglottis is a flap of tissue that covers the trachea during swallowing, preventing food from entering the lungs. When food is swallowed, the epiglottis closes off the trachea to ensure that the food goes down the esophagus into the stomach.
Incorrect choices:
A: The pyloric sphincter is a valve located between the stomach and the small intestine, regulating the flow of partially digested food.
B: The trachea is the windpipe that connects the larynx to the bronchi, allowing air to pass into the lungs.
C: The pharynx is the throat area where the pathways for both food and air cross, but it is the epiglottis that specifically prevents food from entering the lungs.
Which of the following drugs has muscarinic and nicotinic actions and is resistant to hydrolysis by both true and pseudo cholinesterase:
- A. Acetylcholine
- B. Carbachol
- C. Bethanechol
- D. Succinylcholine
Correct Answer: B
Rationale: Step-by-step rationale for why B (Carbachol) is the correct answer:
1. Carbachol is a cholinergic drug that acts on both muscarinic and nicotinic receptors.
2. It is resistant to hydrolysis by both true and pseudo cholinesterase enzymes.
3. Acetylcholine (A) is rapidly hydrolyzed by both cholinesterases.
4. Bethanechol (C) is a muscarinic agonist but not a nicotinic agonist.
5. Succinylcholine (D) is a depolarizing neuromuscular blocking agent, not a cholinergic agonist.
Summary:
Carbachol is the only drug among the choices that has both muscarinic and nicotinic actions and is resistant to hydrolysis by cholinesterases. Acetylcholine is rapidly hydrolyzed, Bethanechol does not have nicotinic actions, and Succinyl
This hormone stimulates osteoclastic activity, causing bone resorption.
- A. Calcitonin
- B. Androgen
- C. PTH
- D. Thyroxine
Correct Answer: C
Rationale: The correct answer is C: PTH. Parathyroid hormone (PTH) stimulates osteoclastic activity, leading to bone resorption. PTH plays a crucial role in regulating calcium levels in the blood. When calcium levels are low, PTH is released to stimulate the release of calcium from bones through osteoclast activity.
A: Calcitonin actually inhibits osteoclastic activity, promoting bone formation.
B: Androgen is a male sex hormone and does not directly influence bone resorption.
D: Thyroxine is a thyroid hormone that regulates metabolism and does not directly affect bone resorption.
Which of the following hormones are responsible for the 'fight-or-flight' response?
- A. Epinephrine and norepinephrine.
- B. Insulin and glucagon.
- C. Esrtogen and progesterone.
- D. Thyroxin and melatonin.
Correct Answer: A
Rationale: The correct answer is A: Epinephrine and norepinephrine. These hormones are released by the adrenal glands during stressful situations to trigger the 'fight-or-flight' response. They increase heart rate, blood pressure, and energy production to prepare the body for action. Insulin and glucagon (B) regulate blood sugar levels. Estrogen and progesterone (C) are female sex hormones. Thyroxin and melatonin (D) are involved in metabolism and sleep regulation, respectively. Therefore, only A directly relates to the physiological response of 'fight-or-flight'.