All of the following physiological changoccur during REM sleep, EXCEPT?

Correct Answer: D

Rationale: Increased spinal reflex, which is false. REM sleep featurmotor inhibition (atonia), reducing spinal reflexto prevent acting out dreams, per polysomnography. Choice A is true; cerebral blood flow rises, supporting brain activity. Choice B is correct; temperature increasslightly. Choice C is accurate; EEG shows desynchronized, rapid waves. Choice D is true; vivid dreams define REM. falsehood reflexdecrease, as in REM atonia preventing movement contrasts with the active brain statof A-D, making it the exception and correct answer.

Correct Answer: D

Rationale: Realization , which is not a defense mechanism. Realization is conscious awareness, not a protective process. Choice A (regression) reverts to childish behavior; B (reaction formation) flips impulses; C (repression) burithoughts justifiactions all Freudian defenses. Unconscious distortion, makes itthe exception. Per psychoanalytic theory, defensmitigate anxiety, while realization reflects insight, not protection, making D the correct answer.

Correct Answer: D

Rationale: Hydrocephalus is a condition characterized by an abnormal accumulation of cerebrospinal fluid (CSF) within the brain, leading to increased intracranial pressure. This can cause the skull to expand and take on a square or boxlike shape, especially in infants whose cranial suturhave not yet fused. Kleinfelter syndrome is a genetic disorder involving an extra X chromosome in males, primarily affecting sexual development and not skull shape. Neurofibromatosis is a genetic condition causing tumors along nervbut donot typically alter skull shape in this manner. Storage disorders , such as lysosomal storage diseases, lead to accumulation of substancwithin cells but are not associated with a boxlike skull. Chronic subdural hemorrhagcould cause other cranial changes, but not this specific shape. Thus, hydrocephalus is the correct answer due to its direct impact on skull morphology through fluid pressure.

Correct Answer: D

Rationale: Cranial CT is highly effective for detecting structural abnormalitilike skull fractur, intracranial hemorrhag, and acute infarcts due to its speed and sensitivity to bone and blood. Hydrocephalus is also well-visualized as it shows ventricular enlargement. However, impending herniation is the exception, as CT may not reliably detect early pressure changor subtle tissue shifts indicative of herniation risk, often requiring clinical correlation or MRI for confirmation. While CT can show gross herniation after it occurs, it is less valuable for predicting impending stagcompared to the other conditions, which are directly and immediately visible. Thus, D is the correct answer as the least reliably assessed by CT in this context.

Correct Answer: A

Rationale: Communicating hydrocephalus occurs when CSF flow is blocked after exiting the ventricles, often due to impaired absorption. Achondroplasia causforamen magnum stenosis, leading to communicating hydrocephalus from reduced CSF outflow, making it the correct answer. Aqueductal stenosis causnon-communicating hydrocephalus by blocking flow between ventricles. Chiari malformation and Dandy-Walker malformation also typically result in non-communicating hydrocephalus due to structural obstructions (tonsillar herniation or fourth ventricle cysts). Klippel-Feil syndrome affects cervical vertebrae, not directly causing hydrocephalus. Thus, A uniquely fits the communicating type among these options.