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Which type of neuroglia cell is responsible for forming the myelin
sheath in the peripheral nervous system (PNS)?
A) Astrocytes
B) Microglia
C) Schwann cells
D) Oligodendrocytes
Answer: C. Rationale: Schwann cells form myelin in the PNS, while
oligodendrocytes form myelin in the central nervous system (CNS).
The resting membrane potential of a neuron is primarily maintained
by:
A) Sodium-potassium pump
B) Calcium channels
C) Chloride influx
D) Magnesium block
Answer: A. Rationale: The sodium-potassium pump actively
transports 3 Na+ out and 2 K+ in, maintaining the resting potential
at approximately -70mV.
Which part of the neuron contains the nucleus and is essential for
cell survival?
A) Axon hillock
B) Cell body (soma)
C) Dendrite
D) Axon terminal
Answer: B. Rationale: The cell body (soma) houses the nucleus and
other organelles necessary for the neuron's metabolic functions and
survival.
, An action potential is triggered when a neuron reaches:
A) Repolarization
B) Hyperpolarization
C) Threshold
D) Resting potential
Answer: C. Rationale: Once a neuron reaches threshold (usually
around -55mV), voltage-gated sodium channels open, initiating an
action potential.
Saltatory conduction occurs in:
A) Unmyelinated axons
B) Myelinated axons
C) Dendrites
D) The cell body
Answer: B. Rationale: Saltatory conduction is the "jumping" of an
action potential from one Node of Ranvier to the next in myelinated
axons, increasing conduction speed.
Which neurotransmitter is primarily involved in muscle contraction
at the neuromuscular junction?
A) Dopamine
B) Serotonin
C) Acetylcholine (ACh)
D) GABA
Answer: C. Rationale: Acetylcholine is the neurotransmitter released
by motor neurons to stimulate skeletal muscle contraction.