EDT Neuroanatomy & Physiology 2 — Questions and Answers
Question 1: Which ion channel is primarily responsible for the rising phase of an action potential?
- Voltage-gated potassium channels
- Voltage-gated sodium channels (Correct answer)
- Ligand-gated calcium channels
- Leak chloride channels
Correct answer: Voltage-gated sodium channels
Voltage-gated sodium channels open rapidly in response to membrane depolarization, allowing Na⁺ influx that drives the rising phase of the action potential.
Question 2: The dorsal root ganglion (DRG) contains the cell bodies of which neuron type?
- Lower motor neurons
- Upper motor neurons
- Primary sensory afferent neurons (Correct answer)
- Autonomic preganglionic neurons
Correct answer: Primary sensory afferent neurons
The DRG houses the cell bodies of primary sensory (afferent) neurons that transmit sensory signals from the periphery to the spinal cord.
Question 3: What is the approximate conduction velocity range for Aβ sensory fibers?
- 0.5–2 m/s
- 5–15 m/s
- 30–70 m/s (Correct answer)
- 70–120 m/s
Correct answer: 30–70 m/s
Aβ fibers are myelinated and conduct at 30–70 m/s, carrying touch and pressure information.
Question 4: Which spinal cord tract carries proprioceptive information ipsilaterally to the cerebellum?
- Lateral spinothalamic tract
- Dorsal columns
- Dorsal spinocerebellar tract (Correct answer)
- Corticospinal tract
Correct answer: Dorsal spinocerebellar tract
The dorsal spinocerebellar tract conveys unconscious proprioceptive signals from the lower limb ipsilaterally to the cerebellum.
Question 5: Saltatory conduction in myelinated nerves occurs because action potentials jump between which structures?
- Dendrites
- Axon hillocks
- Nodes of Ranvier (Correct answer)
- Synaptic terminals
Correct answer: Nodes of Ranvier
In myelinated fibers, depolarization skips from one node of Ranvier to the next, dramatically increasing conduction velocity.
Question 6: The anterior horn of the spinal cord gray matter primarily contains cell bodies of which neurons?
- Sensory neurons
- Interneurons only
- Lower motor neurons (alpha motor neurons) (Correct answer)
- Postganglionic sympathetic neurons
Correct answer: Lower motor neurons (alpha motor neurons)
Alpha motor neurons located in the anterior horn innervate skeletal muscle fibers and are the final common pathway for voluntary movement.
Question 7: Which neurotransmitter is released at the neuromuscular junction?
- Norepinephrine
- Dopamine
- Acetylcholine (Correct answer)
- Serotonin
Correct answer: Acetylcholine
Acetylcholine is released from motor nerve terminals and binds nicotinic receptors on the motor end plate to trigger muscle depolarization.
EDT Neuroanatomy & Physiology 2
Which ion channel is primarily responsible for the rising phase of an action potential?