Muscarinic receptors are located in:

Correct Answer: C

Rationale: Muscarinic receptors are located in autonomic effector cells. These receptors respond to acetylcholine released by parasympathetic nerves in organs like the heart, smooth muscle, and glands. They play a key role in regulating functions such as heart rate, digestion, and glandular secretions. Autonomic ganglia (A) contain nicotinic receptors, not muscarinic. Skeletal muscle neuromuscular junctions (B) have nicotinic receptors. Sensory carotid sinus baroreceptor zone (D) is not directly involved in cholinergic signaling. Hence, the correct answer is C.

Correct Answer: C

Rationale: The correct answer is C: Tachycardia. Direct beta1-adrenoreceptor stimulation leads to an increase in heart rate by enhancing the conduction of electrical impulses in the heart. Beta1 receptors are primarily located in the heart, particularly in the sinoatrial node, atria, and ventricles. This stimulation results in an increased rate of depolarization, leading to tachycardia. Choices A and B are incorrect because beta2 receptors are responsible for bronchodilation and vasodilation, respectively. Choice D is incorrect because bradycardia is not associated with direct beta1-adrenoreceptor stimulation.

Correct Answer: B

Rationale: The correct answer is B: Phentolamine. This drug is a nonselective alpha receptor antagonist, blocking both alpha-1 and alpha-2 receptors. It is used to treat hypertensive emergencies. Prazosin (A) is a selective alpha-1 receptor antagonist, used for hypertension and BPH. Metoprolol (C) is a beta blocker, mainly blocking beta-1 receptors for heart conditions. Reserpine (D) inhibits the uptake of norepinephrine into vesicles, reducing sympathetic activity.

Correct Answer: D

Rationale: The correct answer is D because all three options (A, B, and C) are used in the treatment of insomnia. Benzodiazepines, such as diazepam, help induce sleep. Imidazopyridines, like zolpidem, also aid in sleep. Barbiturates, such as phenobarbital, have sedative effects. Therefore, all of the above options are valid treatments for insomnia.

Correct Answer: C

Rationale: The correct answer is C: Clonazepam. Clonazepam is a benzodiazepine commonly used for myoclonic seizures due to its ability to enhance the inhibitory neurotransmitter GABA in the brain, reducing seizure activity. Primidone (A), Carbamazepine (B), and Phenytoin (D) are more commonly used for other types of seizures like focal or generalized tonic-clonic seizures, not specifically for myoclonic seizures.