Neurophysiology Set 1

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MCQ

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1. Clostridium botulinum toxin affecting the
neuromuscular junction by the following
mechanism :

A) Causes explosive release of ACh

B) Reversibly binds (compete with ACh) with ACh receptor sites

C) Blocks release of ACh

D) Blocks choline reuptake into presynaptic terminals

E) Irreversibly inhibits acetylcholinesterase (AChE)

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2. Which of the following statements about nerve growth factor is
not true :

A) It is made up of three polypeptide subunits

B) It is responsible for the growth and maintenance of adrenergic neurons in the basal forebrain and the striatum.

C) It is necessary for the growth and development of the sympathetic nervous system

D) It is picked up by nerves from the organs they innervate

E) It can express both p75 NTR and Trk A receptors

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3. The functions of tropomyosin in skeletal muscle include

A) sliding on actin to produce shortening

B) releasing Ca 2+ after initiation of contraction

C) binding to myosin during contraction

D) acting as a “relaxing protein” at rest by covering up the sites where myosin binds to actin

E) generating ATP, which it passes to the contractile mechanism

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4. Which of the following is best described as an elongated, encapsulated receptor found in the dermal
pegs of glabrous skin and is especially abundant on lips and fingertips?

A) Merkel’s disc

B) Free nerve endings

C) Meissner’s corpuscle

D) Ruffini’s endings

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5. The velocity of nerve conduction is increased with a decrease in the:

A) Space constant of the nerve fiber

B) Resting membrane potential

C) Diameter of the nerve fiber

D) Degree of myelination

E) Capacitance of the nerve fiber membrane

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6. Which of these cells are not a type of neuroglia found in the CNS :

A) Astrocytes

B) Schwann Cells

C) Ependymal Cells

D) Microglia

E) Oilgodendrocytes

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7. A man falls into a deep sleep with one arm under his head.
Th is arm is paralyzed when he awakens, but it tingles, and pain
sensation in it is still intact. Th e reason for the loss of motor
function without loss of pain sensation is that in the nerves
to his arm :

A) A fi bers are more susceptible to hypoxia than B fi bers.

B) A fi bers are more sensitive to pressure than C fi bers

C) C fi bers are more sensitive to pressure than A fi bers

D) Motor nerves are more aff ected by sleep than sensory nerves

E) Sensory nerves are nearer the bone than motor nerves and hence are less aff ected by pressure

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8. Which of the following is the system that transmits somatosensory information with the highest
degree of temporal and spatial fidelity?

A) Anterolateral system

B) Dorsal column–medial lemniscal system

C) Corticospinal system

D) Spinocerebellar system

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9. Which of the following substances enhances the sensitivity of pain receptors but does not directly
excite them?

A) Bradykinin

B) Serotonin

C) Potassium ions

D) Prostaglandins

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10. Initiation of an action potential in skeletal muscle :

A) requires spatial facilitation

B) requires temporal facilitation

C) is inhibited by a high concentration of Ca 2+ at the neuromuscular junction

D) requires the release of norepinephrine

E) requires the release of acetylcholine

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11. Hypoventilation has which of the following effects on neuronal activity?

A) Depresses neuronal activity

B) Increases neuronal activity

C) Increases synaptic delay

D) Increases neurotransmitter release

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12. The first-order (primary afferent) cell bodies of the dorsal column–medial lemniscal system are
found in which of the following structures?

A) Spinal cord dorsal horn

B) Spinal cord ventral horn

C) Dorsal root ganglia

D) Nucleus cuneatus

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13. Which of the following represents the basis for transduction of a sensory stimulus into nerve
impulses?

A) Change in the ion permeability of the receptor membrane

B) Generation of an action potential

C) Inactivation of a G-protein–mediated response

D) Protein synthesis

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14. In a neuron with a resting membrane potential of −65mV, the distribution of which ion across the
neuronal membrane represents the greatest potential electromotive force (EMF)?

A) Potassium

B) Chloride

C) Sodium

D) Calcium

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15. Which of the following best describes an expanded tip tactile receptor found in the dermis of hairy
skin that is specialized to detect continuously applied touch sensation?

A) Free nerve endings

B) Merkel’s disc

C) Pacinian corpuscle

D) Ruffini’s endings

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16. The action potential of skeletal muscle :

A) has a prolonged plateau phase

B) spreads inward to all parts of the muscle via the T tubules

C) causes the immediate uptake of Ca 2+ into the lateral sacs of the sarcoplasmic reticulum.

D) is longer than the action potential of cardiac muscle.

E) is not essential for contraction

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17. The release of neurotransmitter at a chemical synapse in the central nervous system is dependent upon
which of the following?

A) Synthesis of acetylcholinesterase

B) Hyperpolarization of the synaptic terminal

C) Opening of ligand-gated ion calcium channels

D) Influx of calcium into the presynaptic terminal

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18. Pain receptors in the skin are typically classified as which of the following?

A) Encapsulated nerve endings

B) Single class of morphologically specialized receptors

C) Same type of receptor that detects position sense

D) Free nerve endings

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19. Excitation-contraction coupling in smooth muscle is initiated when calcium bind to :

A) Tropomyosin

B) Protein kinase A

C) Troponin

D) Myosin light chains

E) Calmodulin

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20. Which of the following is not correctly paired :

A) Synaptic transmission: Antidromic conduction

B) Molecular motors: Dynein and kinesin

C) Fast axonal transport: ~400 mm/day

D) Slow axonal transport: 0.5–10 mm/day

E) Nerve growth factor: Retrograde transport

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21. The cross-bridges of the sarcomere in skeletal muscle are made
up of

A) actin

B) myosin

C) troponin

D) tropomyosin

E) myelin

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22. Forced rapid breathing results in alkalization of the blood which would lead to which of the
following changes in neuronal activity?

A) Decrease in neuronal activity

B) Increase in neuronal activity

C) Initial decrease followed by an increase

D) No change in neuronal activity

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23. A 35-year-old woman sees her physician to report muscle
weakness in the extraocular eye muscles and muscles of the
extremities. She states that she feels fine when she gets up in
the morning, but the weakness begins soon after she becomes
active. The weakness is improved by rest. Sensation appears
normal. The physician treats her with an anticholinesterase
inhibitor, and she notes immediate return of muscle strength.
Her physician diagnoses her with

A) Lambert–Eaton syndrome

B) myasthenia gravis

C) multiple sclerosis

D) Parkinson disease

E) muscular dystrophy

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24. Gap junctions :

A) are absent in cardiac muscle

B) are present but of little functional importance in cardiac muscle

C) are present and provide the pathway for rapid spread of excitation from one cardiac muscle fi ber to another

D) are absent in smooth muscle

E) connect the sarcotubular system to individual skeletal muscle cells

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25. Which of the following is an important functional parameter of pain receptors?

A) Exhibit little or no adaptation

B) Not affected by muscle tension

C) Signal only flexion at joint capsules

D) Can voluntarily be inhibited

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Neurophysiology Set 1

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