A client who is about to begin chemotherapy for colon cancer expresses concern about the effects of the drugs on the brain. The nurse can reassure this client based on knowledge of what protective feature of the central nervous system (CNS)?

Correct Answer: B

Rationale: The blood-brain barrier restricts drug entry into the CNS, protecting the brain from many chemotherapy agents. CSF cushions, myelin insulates, neuroglia support.

Correct Answer: C

Rationale: The thalamus is a major structure in the diencephalon, part of the forebrain, acting as a relay station for sensory and motor signals. It is not in the telencephalon (cerebrum), mesencephalon (midbrain), metencephalon (pons/cerebellum), or myelencephalon (medulla).

Correct Answer: B

Rationale: Delta waves (slow, high-amplitude) occur in deep sleep in healthy individuals and can appear in awake brain-damaged patients, indicating dysfunction. Alpha (relaxed), beta (alert), and theta (light sleep) have different contexts.

Correct Answer: A

Rationale: The choroid plexus is a network of capillaries in the ventricles (third and fourth) that produces cerebrospinal fluid (CSF). The circle of Willis is an arterial ring, and the other terms are incorrect or fictional.

Correct Answer: C

Rationale: Theta waves (4-8 Hz) in adults while awake often indicate brain dysfunction or damage, common in pathological states. They occur normally in children or during light sleep/dreaming, but not typically in healthy awake adults.