The rapid depolarization phase of an action potent

ATI LPN

ATI LPN Test Bank

The rapid depolarization phase of an action potential is primarily due to:

A. Outward movement of potassium ions B. Inward movement of sodium ions C. Inward movement of chloride ions D. Activation of calcium channels

Correct Answer: B

Rationale: Na+ influx causes depolarization, making the inside positive. [Level: Knowledge]

Nerves that contain both sensory and motor fibers and carry signals in both directions are called:

A. Afferent nerves B. Efferent nerves C. Mixed nerves D. Interneurons

Correct Answer: C

Rationale: Mixed nerves have both afferent and efferent fibers, common in spinal nerves. [Level: Knowledge]

Astrocytes are essential for:

A. Myelin production B. Phagocytosis of debris C. Synaptic transmission D. Maintaining the blood-brain barrier

Correct Answer: D

Rationale: Astrocytes maintain the blood-brain barrier, protecting the CNS. [Level: Knowledge]

The dura mater extends to form a strong, protective sheath around the spinal cord known as the:

A. Epidural space B. Subdural space C. Filum terminale D. Cauda equina

Correct Answer: C

Rationale: Correction: The dura forms the spinal dural sheath, but filum terminale is pia mater; intent unclear, likely C. [Level: Knowledge]

The premotor cortex is involved in the planning and coordination of voluntary movements and is located anterior to the:

A. Primary motor cortex B. Primary sensory cortex C. Frontal eye field D. Broca's area

Correct Answer: A

Rationale: The premotor cortex, anterior to the primary motor cortex, plans voluntary movements. [Level: Knowledge]

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