Question 1

Which type of glial cell is primarily responsible for forming the myelin sheath in the central nervous system (CNS)?

Accepted Answer

Oligodendrocytes

Question 2

During embryonic development, which structure gives rise to the central nervous system (CNS)?

Accepted Answer

Neural tube

Question 3

A patient presents with loss of sensation in the skin over the lateral thigh. Which plexus is most likely involved?

Accepted Answer

Lumbosacral plexus

Question 4

Which equation best represents the Nernst potential for potassium ($$K^+) $$across a neuronal membrane?

Accepted Answer

$$E_{K^+} = \frac{RT}{zF} \ln \left( \frac{[K^+]_{out}}{[K^+]_{in}} \right)$$

Question 5

Which of the following best describes the function of the blood-brain barrier (BBB)?

Accepted Answer

It regulates the passage of substances between the blood and CNS, protecting neural tissue.

Question 6

Which glial cell type is responsible for producing cerebrospinal fluid (CSF) in the CNS?

Accepted Answer

Ependymal cells

Question 7

A reflex arc involves which correct sequence of structures?

Accepted Answer

Receptor → Sensory neuron → CNS → Motor neuron → Effector

Question 8

Which neurotransmitter is released at the neuromuscular junction (NMJ) to stimulate muscle contraction?

Accepted Answer

Acetylcholine

Question 9

If the resting membrane potential of a neuron is $$-70\ \mathrm{mV}$$, what happens when the membrane depolarizes to threshold?

Accepted Answer

Voltage-gated $$Na^+$$ channels open, causing rapid influx of $$Na^+$$ and initiation of an action potential.

Question 10

Which of the following statements about white and gray matter in the spinal cord is correct?

Accepted Answer

White matter consists mainly of myelinated axons organized into tracts.

Question 11

A lesion affecting the dorsal root of a spinal nerve would most likely result in which clinical finding?

Accepted Answer

Loss of sensory input from the affected region

Question 12

Which equation describes the relationship between membrane potential ($$V_m$$), ion concentrations, and permeability according to the Goldman-Hodgkin-Katz equation?

Accepted Answer

$$V_m = \frac{RT}{F} \ln \left( \frac{P_{K^+}[K^+]_{out} + P_{Na^+}[Na^+]_{out} + P_{Cl^-}[Cl^-]_{in}}{P_{K^+}[K^+]_{in} + P_{Na^+}[Na^+]_{in} + P_{Cl^-}[Cl^-]_{out}} \right)$$

Question 13

Which of the following best explains why action potentials only travel in one direction along an axon?

Accepted Answer

Refractory periods prevent the reactivation of voltage-gated channels behind the action potential.

Question 14

Which structure in the spinal cord contains preganglionic neurons of the autonomic nervous system?

Accepted Answer

Lateral horn

Question 15

A patient has damage to the ventral root of a spinal nerve. Which function is most likely impaired?

Accepted Answer

Motor control of skeletal muscles

Question 16

Which of the following is a correct description of a chemical synapse?

Accepted Answer

Neurotransmitters are released from the presynaptic neuron and bind to receptors on the postsynaptic cell.

Question 17

Which layer of the developing neural tube is responsible for neurogenesis and contains the cell bodies of neurons?

Accepted Answer

Mantle layer

Question 18

Which of the following best describes the function of Schwann cells?

Accepted Answer

They form myelin sheaths around axons in the peripheral nervous system.

Question 19

Which of the following is true regarding the organization of spinal nerves?

Accepted Answer

Spinal nerves are mixed, containing both sensory and motor fibers.

Question 20

Which of the following best describes the role of dermatomes?

Accepted Answer

They are regions of skin innervated by sensory fibers from a single spinal nerve.

Nervous System I: Embryology and Early Development of the Spinal Cord

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