Nerve

Question 1

Which cell type myelinates axons in the peripheral nervous system?
A. Oligodendrocytes
B. Schwann cells
C. Astrocytes
D. Microglia

Answer 1

B. Schwann cells

Question 2

The resting membrane potential is primarily maintained by which ion’s leak channels?
A. Sodium (Na+)
B. Calcium (Ca2+)
C. Potassium (K+)
D. Chloride (Cl−)

Answer 2

C. Potassium (K+)

Question 3

According to the Goldman-Hodgkin-Katz equation, membrane potential depends on:
A. Ion concentrations only
B. Membrane permeability and ion concentrations
C. Temperature only
D. Electrical stimulation

Answer 3

B. Membrane permeability and ion concentrations

Question 4

What occurs during the depolarization phase of an action potential?
A. Opening of voltage-gated K+ channels
B. Influx of Na+ through voltage-gated Na+ channels
C. Efflux of Na+
D. Inactivation of Na+/K+ pumps

Answer 4

B. Influx of Na+ through voltage-gated Na+ channels

Question 5

The absolute refractory period is characterized by:
A. Sodium channels being inactivated and inability to initiate another action potential
B. Potassium channels being closed
C. Decrease in membrane potential below resting levels
D. Increased neuronal excitability

Answer 5

A. Sodium channels being inactivated and inability to initiate another action potential

Question 6

Which statement best distinguishes local potentials from action potentials?
A. Local potentials follow the all-or-none law
B. Action potentials are graded, local potentials are not
C. Local potentials can be hyperpolarizing or depolarizing, action potentials are always depolarizing
D. Local potentials always propagate without decrement

Answer 6

C. Local potentials can be hyperpolarizing or depolarizing, action potentials are always depolarizing

Question 7

Saltatory conduction in myelinated nerves occurs between:
A. Soma and dendrites
B. Axon hillock and dendrites
C. Nodes of Ranvier
D. Synaptic boutons

Answer 7

C. Nodes of Ranvier

Question 8

What is the main function of astrocytes in the CNS?
A. Myelination of neurons
B. Regulation of neurotransmitters and the blood-brain barrier
C. Phagocytosis of pathogens
D. Production of cerebrospinal fluid

Answer 8

B. Regulation of neurotransmitters and the blood-brain barrier

Question 9

In peripheral nerve injury classified as neuropraxia, what is the expected prognosis?
A. Permanent loss of nerve function
B. Temporary loss with full recovery within weeks
C. Irreversible nerve degeneration
D. Complete regeneration with no deficits

Answer 9

B. Temporary loss with full recovery within weeks

Question 10

Which ion’s concentration gradient most strongly influences the resting membrane potential?
A. Na+
B. Cl–
C. Ca2+
D. K+

Answer 10

D. K+

Question 11

Mechanically gated ion channels open in response to:
A. Voltage change
B. Binding of neurotransmitters
C. Physical deformation such as stretch
D. Temperature changes only

Answer 11

C. Physical deformation such as stretch

Question 12

Which of the following is a key feature of pseudounipolar neurons?
A. Two dendrites and one axon
B. Single process that bifurcates into peripheral and central branches
C. Absence of an axon
D. Only found in the CNS

Answer 12

B. Single process that bifurcates into peripheral and central branches

Question 13

Which neuroglial cell acts as the brain’s immune system by phagocytosis?
A. Astrocytes
B. Oligodendrocytes
C. Microglia
D. Ependymal cells

Answer 13

C. Microglia

Question 14

Which ion channel opens first during the rising phase of the action potential?
A. Voltage-gated K+ channels
B. Voltage-gated Na+ channels
C. Ligand-gated Cl− channels
D. Leak K+ channels

Answer 14

B. Voltage-gated Na+ channels

Question 15

Ligand-gated ion channels differ from voltage-gated channels in that:
A. They open in response to changes in membrane potential
B. They open in response to the binding of a chemical messenger
C. They require ATP to open
D. They only allow potassium ions to pass

Answer 15

B. They open in response to the binding of a chemical messenger

Question 16

The strength-duration curve in nerve studies helps to determine:
A. Conduction velocity
B. Nerve excitability and degree of denervation
C. Muscle strength via electromyography
D. Anatomical localization of nerve lesions

Answer 16

B. Nerve excitability and degree of denervation

Question 17

Which ion pumps 3 Na+ ions out and 2 K+ ions into the cell, helping maintain resting membrane potential?
A. Voltage-gated Na+ channel
B. Na+/K+ ATPase pump
C. Ca2+ ATPase pump
D. Ligand-gated K+ channel

Answer 17

B. Na+/K+ ATPase pump

Question 18

Which neurotransmitter is primarily involved in the peripheral somatic neuromuscular junction?
A. Dopamine
B. Acetylcholine
C. GABA
D. Glutamate

Answer 18

B. Acetylcholine

Question 19

Voltage-gated Ca2+ channels in the presynaptic terminal open in response to:
A. Membrane hyperpolarization
B. Depolarization following the action potential
C. Neurotransmitter binding
D. Ion diffusion

Answer 19

B. Depolarization following the action potential

Question 20

The threshold membrane potential to trigger an action potential is approximately:
A. -90 mV
B. -70 mV
C. -55 mV
D. 0 mV

Answer 20

C. -55 mV

Question 21

Spatial summation in neurons occurs when:
A. One presynaptic neuron fires rapidly in succession
B. Multiple synapses on different parts of the neuron fire simultaneously
C. Postsynaptic potentials occur in different neurons simultaneously
D. A synaptic potential directly triggers neurotransmitter release

Answer 21

B. Multiple synapses on different parts of the neuron fire simultaneously

Question 22

Presynaptic inhibition reduces neurotransmitter release mainly through:
A. Direct inhibition of postsynaptic receptors
B. Reduction in Ca2+ influx into the presynaptic terminal
C. Increased K+ efflux from postsynaptic neuron
D. Blocking of action potential generation in presynaptic neuron

Answer 22

B. Reduction in Ca2+ influx into the presynaptic terminal

Question 23

Which of these components is NOT part of the axon terminal synaptic vesicle machinery?
A. Synaptobrevin
B. Syntaxin
C. Synaptotagmin
D. Myelin basic protein

Answer 23

D. Myelin basic protein

Question 24

The Na+/K+ ATPase pump contributes to:
A. Depolarization phases of the action potential
B. Restoring ion gradients after the action potential
C. Opening voltage-gated sodium channels
D. Generation of EPSPs

Answer 24

B. Restoring ion gradients after the action potential

Question 25

What is the typical concentration of intracellular calcium relative to the extracellular space? A. Equal concentration inside and out B. Higher inside than outside C. Much lower inside than outside D. Variable based on neurons

Answer 25

C. Much lower inside than outside

Question 26

Which factor does NOT affect nerve conduction velocity? A. Myelination B. Axon diameter C. Temperature D. Strength of stimulus

Answer 26

D. Strength of stimulus

Question 27

In the peripheral nervous system, satellite glial cells primarily: A. Myelinate axons B. Surround neuronal cell bodies in ganglia and regulate microenvironment C. Clear pathogens by phagocytosis D. Produce cerebrospinal fluid

Answer 27

B. Surround neuronal cell bodies in ganglia and regulate microenvironment

Question 28

The Nernst equation calculates: A. Resting membrane potential considering multiple ions B. Equilibrium potential for a single ion C. The ionic current through voltage-gated channels D. The permeability of ion channels

Answer 28

B. Equilibrium potential for a single ion

Question 29

Which of the following is TRUE about the relative refractory period? A. No new action potential can be generated B. A stronger than normal stimulus is required to initiate an action potential C. The membrane potential is hyperpolarized but not recoverable D. It occurs only during the resting phase

Answer 29

B. A stronger than normal stimulus is required to initiate an action potential

Question 30

Which clinical toxin blocks voltage-gated sodium channels, preventing depolarization and leading to paralysis? A. Tetrodotoxin B. Botulinum toxin C. Curare D. Organophosphates

Answer 30

A. Tetrodotoxin

Question 31

This neuroglial cell maintains the BBB, controls the levels of neurotransmitters, and provides metabolic support by ion regulation.

Answer 31

Astrocytes

Question 32

TRUE OR FALSE: Neurons are incapable of being fatigued

Answer 32

True

Question 33

Which neuroglial cell regulate neurotransmitters in the PNS

Answer 33

Satellite Cells

Question 34

The Nernst equation is used to calculate: A. The resting membrane potential when multiple ions are involved B. The equilibrium potential for a single ion species C. The ion concentrations inside the cell D. The magnitude of an action potential

Answer 34

B. The equilibrium potential for a single ion species

Question 35

According to the Nernst equation, the equilibrium potential (E) for potassium (K⁺) is negative because: A. Its concentration is higher inside the cell than outside B. Electrical and chemical gradients are equal C. Potassium ions are negatively charged D. Its permeability is always zero

Answer 35

A. Its concentration is higher inside the cell than outside

Question 36

What is the approximate extracellular concentration of sodium (Na⁺) relative to intracellular? A. Lower than inside the cell B. About equal inside and outside C. Much higher outside the cell than inside D. Very low, almost zero

Answer 36

C. Much higher outside the cell (~145 mM) than inside (~10 mM) Na+ concentration: Out - 145mM In - 10nM

Question 37

During depolarization of an action potential, which ion channel opens first? A. Voltage-gated potassium (K⁺) channels B. Voltage-gated sodium (Na⁺) channels C. Leak potassium channels D. Chloride channels

Answer 37

B. Voltage-gated sodium (Na⁺) channels

Question 37

The resting membrane potential is closest to which of the following values? A. +60 mV B. 0 mV C. -75 mV D. +30 mV

Answer 37

C. -75 mV Range = -70-90 mV

Question 38

What happens to the sodium channels immediately after peak depolarization? A. Remain open B. Close via an inactivation gate and become temporarily non-conductive C. Begin to open wider D. Convert to potassium channels

Answer 38

B. Close via an inactivation gate and become temporarily non-conductive

Question 39

Which phase of the action potential is caused by opening of voltage-gated potassium channels? A. Depolarization B. Repolarization C. Hyperpolarization D. Threshold

Answer 39

B. Repolarization

Question 40

Hyperpolarization following an action potential is due mainly to: A. Excess sodium entry B. Opening of chloride channels only C. Slow closing of potassium channels causing an efflux of K⁺ D. Inactivation of the sodium-potassium pump

Answer 40

C. Slow closing of potassium channels causing an efflux of K⁺

Question 41

Which of the following accurately describes the sequence of events during an action potential? A. Depolarization → Repolarization → Threshold → Hyperpolarization B. Threshold → Depolarization → Repolarization → Hyperpolarization C. Repolarization → Depolarization → Hyperpolarization → Threshold D. Hyperpolarization → Depolarization → Threshold → Repolarization

Answer 41

B. Threshold → Depolarization → Repolarization → Hyperpolarization

Question 42

Which neuroglial cell type in the CNS is primarily responsible for producing myelin? A. Schwann cells B. Astrocytes C. Oligodendrocytes D. Microglia

Answer 42

C. Oligodendrocytes

Question 43

Which neuroglial cells surround neuron cell bodies in peripheral ganglia and regulate neurotransmitter levels? A. Oligodendrocytes B. Satellite cells C. Microglia D. Schwann cells

Answer 43

B. Satellite cells

Question 44

The intracellular concentration of chloride (Cl⁻) is generally: A. Higher than extracellular concentration B. Equal inside and outside the cell C. Much lower compared to extracellular D. Nearly zero inside the cell

Answer 44

C. Much lower compared to extracellular Cl- concentration: In - 10mM Out - 110mM

Question 45

In the maintenance of resting membrane potential, the Na⁺/K⁺ pump moves: A. 2 Na⁺ out and 3 K⁺ in B. 3 Na⁺ out and 2 K⁺ in C. Equal amounts of Na⁺ and K⁺ in both directions D. Only Na⁺ out, no K⁺ movement

Answer 45

B. 3 Na⁺ out and 2 K⁺ in

Question 46

TRUE OR FALSE: Both motor and sensory neurons, together with the ganglion are found in the PNS

Answer 46

True

Question 47

TRUE OR FALSE: The Na+/K+ ATPase is active at all times

Answer 47

True

Question 48

TRUE OR FALSE: Action potentials are same in size

Answer 48

True

Question 49

Unmyelinated axon A. low membrane resistance, slow conduction velocity B. low membrane resistance, fast conduction velocity C. high membrane resistance, slow conduction velocity D. high membrane resistance, fast conduction velocity

Answer 49

A. low membrane resistance, slow conduction velocity

Question 50

If the conduction velocity of a human nerve fiber was 0.5m/s, how long would it take you to withdraw your foot from a hot spot? A. 0.1s B. 0.5s C. 1s D. 4s

Answer 50

B. 0.5s

Question 51

The following statements are true about compound action potential, except: A. amplitude 2-4mV B. monophasic in shape C. requires external ES D. requires less specialized equipments of extracellular recording

Answer 51

B. monophasic in shape it is biphasic

Question 51

Which of the following does NOT affect the rate of conduction: A. myelin B. nerve diameter C. nerve length D. temperature

Answer 51

C. nerve length

Question 51

What is the Nernst Potential for K?

Answer 51

-90 mV

Question 51

What is the Nernst Potential for Na+?

Answer 51

+60 mV

Question 52

TRUE OR FALSE: K is permeable to the membrane

Answer 52

True

Question 53

what is the mM level of K inside the cell?

Answer 53

140 mM

Question 54

what is the mM level of Na+ inside the cell?

Answer 54

145 mM

Question 55

Which ion hyperpolarizes the cell?

Answer 55

Chloride

Question 56

What is the RMP of nerves?

Answer 56

-90mV