Deck 4: Neuronal Function in the Nervous System

Question 1

A neural impulse is transmitted across the synaptic cleft primarily through ___ means.

A)thermal
B)chemical
C)electrical
D)metabolic

Answer 1

B
The transmission of a neural impulse across the synaptic juncture is primarily a chemical process,although it is occasionally a chemical and electrical process.

Question 2

___is found in high concentration outside the cell.

A)Protein anions
B)Sodium
C)Potassium
D)Calcium

Answer 2

B
Sodium and chloride ions are found in high concentrations in the extracellular fluid.

Question 3

Channels in the cell membrane:

A)are always gated
B)help maintain the concentration gradient
C)may be voltage- or chemically-gated
D)are selective to more than one ion per channel
E)both B and C

Answer 3

E
Channels may be gated or nongated,and help maintain the concentration gradient.The gated channels may be opened by a change in voltage or in the presence of specific chemicals or neurotransmitters.

Question 4

Regarding the concentration gradient,all of the following are true EXCEPT:

A)fluids across a membrane move from a higher to lower concentration
B)the concentration of sodium ions in the interstitial fluid balances the concentration gradient
C)protein ions in the intracellular fluid can permeate the neural cell membrane
D)interstitial fluid contains a higher concentration of water than intracellular fluid
E)sodium ions do not diffuse across the cell membrane

Question 5

An electrical synapse:

A)occurs at the synaptic cleft
B)occurs frequently in mammals
C)occurs at gap junctions between dendrites
D)involves neurotransmitters
E)helps neurons fire sequentially

Question 6

Myelin:

A)is most common in smaller nerve fibers of the peripheral nervous system
B)allows a conduction velocity that is proportional to the square root of the nerve's diameter
C)is produced by the oligodendrocytes in the peripheral nervous system
D)prevents leakage of current from the axon into the extracellular fluid
E)is prevalent at birth

Question 7

Action potentials develop:

A)at the nodes of Ranvier
B)only when a cell is hyperpolarized
C)only in myelinated axons
D)during the absolute refractory period

Question 8

Axons of neurons:

A)vary greatly in number
B)are relatively uniform in regard to conduction velocity
C)conduct nerve impulses toward the neuron's cell body
D)contain ribosomes
E)vary greatly in diameter

Question 9

All of the following are characteristic of an action potential EXCEPT:

A)neural information is signaled by the amplitude of the action potential
B)it is propagated at a constant velocity
C)it is propagated at a constant amplitude
D)it begins at the axon hillock
E)it functions in an all-or-nothing manner

Question 10

A(n)___ potential is propagated from the cell membrane at the point of synapse with another neuron.

A)action
B)resting
C)graded
D)depolarized

Question 11

Which of the following is NOT a component of the synapse?

A)the postsynaptic terminal
B)the axon hillock
C)the synaptic cleft
D)the presynaptic terminal

Question 12

__ is an example of an anion.

A)Potassium
B)Chloride
C)Sodium
D)Calcium

Question 13

During resting potential:

A)the extracellular fluid is 70 mV more negative than the cell's cytoplasm
B)the cell is firing an impulse
C)the cell is actively responding to impulses from other cells
D)the ionic difference across the membrane is at a steady state
E)none of the above

Question 14

The point of contact from one axon to another neuron is the:

A)axoplasm
B)cytoplasm
C)endoplasmic reticulum
D)terminal bouton
E)neurofilament

Question 15

A(n)___ potential is propagated from the axon hillock to the terminal bouton.

A)action
B)resting
C)graded
D)depolarized

Question 16

An adequate stimulus to a neuron may act to:

A)close ion channels
B)prohibit movement of ions across the cell membrane
C)depolarize the cell
D)make the electrical charge inside the cell more negative than that outside of the cell

Question 17

Neurons are classified according to:

A)the number of ribosomes they contain
B)their shape
C)the length of their axons
D)the number of dendrites in each
E)the number of axons they contain

Question 18

___ allow some ions to move against their gradient to provide extra energy to the cell.

A)Voltage gradients
B)Chemical gradients
C)Sodium-potassium pumps
D)Metabolic activities
E)Both A and D

Question 19

Depolarization occurs when:

A)the difference in potential across the cell membrane is −70 mV
B)the difference in potential across the cell membrane is −55 mV
C)the neuron has reached its resting potential
D)there is a discharge of sodium ions into the extracellular space

Question 20

The relative amount of voltage in an electrical field is the definition of:

A)potential
B)irritability
C)resting potential
D)concentration gradient

Question 21

The major inhibitory neurotransmitter is:

A)dopamine
B)epinephrine
C)GABA
D)glutamate
E)the neuropeptides

Question 22

Most of the energy consumed by the nervous system is used for the movement of ions.

Question 23

A neuron with an axon of small diameter will conduct neural impulses faster than a neuron with an axon of a large diameter.

Question 24

Primary neuronal loss:

A)is variable in degree of damage and in the length of time it takes to occur
B)occurs in the region adjacent to the neurological injury
C)occurs immediately following a neurological injury
D)occurs in the vicinity of the neurological injury
E)both C and D

Question 25

A neurotransmitter:

A)serves to open ionic channels in the postsynaptic membrane
B)is stored in the postsynaptic membrane
C)is excitatory,not inhibitory
D)must be inactivated after it is released from the synaptic vesicles
E)both A and D

Question 26

At the synapse,what event must occur before the synaptic vesicles release neurotransmitters?

A)The synaptic vesicles fuse with the presynaptic membrane.
B)The action potential causes voltage-gated channels to release calcium ions.
C)Neurotransmitters cross the synaptic cleft.
D)Neurotransmitters bind to postsynaptic receptors.
E)The neurotransmitters are inactivated by enzymes.

Question 27

The direction of a neural impulse travels from proximal to distal along the dendrites to the soma of neurons.

Question 28

How does degeneration of the CNS differ from that of the PNS?

A)Only in the PNS does degeneration occur distal to the point of injury.
B)Oligodendrocytes,like Schwann cells,provide trophic factors to sprouting axons.
C)Groups of neurons in the vicinity of a lesion are more likely to die in the CNS than PNS.
D)In the PNS,the clearance of debris of necrotic tissue occurs more slowly than in the CNS.

Question 29

In adults,regeneration of neurons and return to function is possible:

A)even if cell bodies are destroyed
B)in the CNS,but not in the PNS
C)only in the hippocampus
D)in the PNS through axonal sprouting if the nerve is not severed

Question 30

A graded potential results in the generation of an action potential.

Question 31

The term used to describe the branching system of neurons into limitless pathways is:

A)convergence
B)divergence
C)the all-or-nothing principle
D)excitatory mechanisms
E)inhibitory mechanisms

Question 32

__ results from an inability to transmit acetylcholine across the synapse to muscle fibers.

A)Myasthenia gravis
B)Parkinson's disease
C)Seizure
D)Muscular dystrophy

Question 33

Delays in speech and language can be linked to delays in the development of myelin.

Question 34

The pumps in the neural membrane open to both sides of the neuron simultaneously.

Question 35

A patient with Parkinson's disease has a deficiency in which neurotransmitter?

A)GABA
B)glutamate
C)l-dopa
D)dopamine