Nokea
The patient is diagnosed with Brown-Séquard syndrome after a knife wound to the spine. Which description accurately describes this syndrome?
- A. Damage to the most distal cord and nerve roots, resulting in flaccid paralysis of the lower limbs and areflexic bowel and bladder
- B. Spinal cord damage resulting in ipsilateral motor paralysis and contralateral loss of pain and sensation below the level of the lesion
- C. Rare cord damage resulting in loss of proprioception below the lesion level with retention of motor control and temperature and pain sensation
- D. Often caused by flexion injury with acute compression of cord resulting in complete motor paralysis and loss of pain and temperature sensation below the level of injury
Correct Answer: B
Rationale: Brown-Séquard syndrome involves ipsilateral motor deficits and contralateral sensory deficits.
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At the scene of the accident in which position should Joe be placed before being transported by ambulance to the emergency room?
- A. The position in which he was found
- B. Lateral position with arms flexed
- C. Supine position with head in neutral position
- D. Supine position with head flexed
Correct Answer: C
Rationale: Neutral head position prevents further spinal injury.
Which of the following statements is FALSE regarding amphibian and mammalian visual systems?
- A. In frog tadpole, neurons from retina project from the left retina to the right optic tectum
- B. Mammalian superior colliculus is analogous to the amphibian optic tectum
- C. In both frog tadpole and mammals, half of the neurons project to the lateral geniculate nuclei (LGN) from the same side; the other half project to LGN on the opposite side
- D. Amphibian neurons from dorsal retina project to lateral side of the tectum
Correct Answer: C
Rationale: The statement that half of the neurons project to the lateral geniculate nuclei (LGN) from the same side in both frog tadpoles and mammals is false. In mammals, most retinal neurons project contralaterally, while in amphibians, the projection pattern is more complex and varies by species. This highlights differences in visual system organization between these groups.
In reviewing Mrs. Post's laboratory results, which abnormal test is most likely to confirm the diagnosis?
- A. Sedimentation rate
- B. Rheumatoid factor
- C. LE cells
- D. Antinuclear antibody
Correct Answer: D
Rationale: Antinuclear antibodies are highly indicative of systemic lupus erythematosus.
Within what approximate time frame does necrosis (cell death) occur because of lack of blood, oxygen, and glucose supplied to the brain?
- A. at least 30 minutes
- B. 20-25 minutes
- C. 12-18 minutes
- D. 4-10 minutes
Correct Answer: D
Rationale: Necrosis, or cell death, can occur within 4-10 minutes of interrupted blood flow to the brain. This underscores the importance of rapid intervention during a stroke to minimize brain damage and improve outcomes.
The action potential of a neuron
- A. is initiated by efflux of Na+
- B. is terminated by efflux of K+
- C. declines in amplitude as it moves along the axon
- D. results in a transient reversal of the concentration gradient of Na+ across the cell membrane
Correct Answer: B
Rationale: The action potential is initiated by the influx of Na+ through voltage-gated sodium channels, causing depolarization. It is terminated by the efflux of K+ through voltage-gated potassium channels, leading to repolarization. The action potential does not decline in amplitude as it propagates along the axon (all-or-none principle), and there is a net movement of Na+ and K+ across the membrane during the process.