A 14-year-old boy is brought to the pediatrician by his mother because of a 1-hour episode of intermittent jerking movements that began around the time he woke up this morning. He describes the movement as jerky, affecting both upper extremities and upper body, and arrhythmic. During the episode, the patient did not lose consciousness. The patient admits to sleeping approximately 4 hours per night due to upcoming final examinations. Physical examination is completely normal. Which of the following is the best initial treatment for this patient’s symptoms?

Correct Answer: A

Rationale: Morning myoclonic jerks without loss of consciousness, triggered by sleep deprivation, suggest juvenile myoclonic epilepsy. Valproic acid is effective for myoclonus and generalized seizures in JME.

Correct Answer: C

Rationale: Effector cells respond to nervous system signals; muscle cells contract and gland cells secrete, executing motor outputs, unlike sensory cells which detect stimuli.

Correct Answer: D

Rationale: Synaptic transmission ends when neurotransmitters are degraded (e.g., by enzymes like acetylcholinesterase) or reuptaken into the presynaptic neuron.

Correct Answer: B

Rationale: The blood-brain barrier regulates the brain’s chemical environment, protecting it from fluctuations; ventricles contain cerebrospinal fluid, not interstitial fluid.

Correct Answer: A

Rationale: The thalamus acts as a relay station, sorting and directing sensory inputs like touch to the appropriate cortical areas.