Question 1

In a neuron at rest, there is a difference in the electrical charge across the cell membrane, with the inside of the cell being more negative than the outside.This is primarily due to

Accepted Answer

A)  leak currents produced by the permeability of the membrane to K+ ions. 
B)  the difference in the concentrations of Na+ inside and outside of the cell. 
C)  the difference in the concentrations of Cl- inside and outside of the cell. 
D)  leak currents produced by the diffusion of Ca2+ ions. 
E)  the difference in concentrations of Ca2+ inside and outside of the cell.

Question 2

In looking at a section through the brain, you see a neuron with a number of shrublike projections extending from one side of the cell body and a single long projection extending from the other side.The shrublike projections are most likely _______, and the single long projection is most likely _______.

Accepted Answer

A)  axons; a dendrite 
B)  Purkinje fibers; the axon 
C)  dendrites; the axon 
D)  axon terminals; the postsynaptic process 
E)  presynaptic processes; the axon hillock

Question 3

Sea stars have a nerve net in each arm.All of the following characterize sea stars except

Accepted Answer

A)  little integration of signals. 
B)  simple neural networks. 
C)  a single ganglion in each arm. 
D)  a limited number of neural networks. 
E)  little processing of signals.

Question 4

Why is it important for a neuron to maintain a membrane potential instead of allowing ions to reach equal concentrations on the two sides of the membrane?

Accepted Answer

A)  The membrane potential maintains fluid balance in the cell. 
B)  The membrane potential allows the cell to respond to a stimulus. 
C)  If the ions were in equilibrium, the cell would swell and burst. 
D)  Maintaining equilibrium would require too much energy. 
E)  The cell must maintain a greater intracellular concentration of positive ions to maintain its cytoskeleton.

Question 5

A particular disease of the nervous system specifically involves the Ca2+ channels at the chemical synapses of motor neurons where neurotransmitter is stored and released.This disease therefore affects the

Accepted Answer

A)  axon terminals of the presynaptic cell and the release of acetylcholine. 
B)  axon terminals of the postsynaptic cell and the release of K+. 
C)  movement of Na+ out of the postsynaptic cell. 
D)  axon terminals of the presynaptic cell and the release of K+. 
E)  axon terminals of the postsynaptic cell and the release of Cl-.

Question 6

Which of the following is not a function of astrocytes?

Accepted Answer

A)  Forming the blood-brain barrier 
B)  Insulating axons 
C)  Supplying nutrients 
D)  Signaling changes in blood composition 
E)  Releasing neurotransmitters

Question 7

Which statement about neuronal membranes is false?

Accepted Answer

A)  Resting neurons are more permeable to potassium than to any other ion. 
B)  The sodium-potassium pump keeps the concentration of potassium higher inside than outside the cell. 
C)  Open chloride channels are largely responsible for the resting membrane potential of neurons. 
D)  Membrane potentials tend toward the equilibrium potential of the ion to which the membrane is most permeable. 
E)  The sodium-potassium pump expels sodium ions from inside the cell.

Question 8

The blood-brain barrier can make it difficult to deliver therapeutic drugs to treat brain disorders.The composition of the blood-brain barrier makes it most easily crossed by

Accepted Answer

A)  fat-soluble substances. 
B)  glucose. 
C)  astrocytes. 
D)  immune cells. 
E)  antibodies.

Question 9

A physical or chemical stimulus can produce a change in a cell's membrane potential by changing the

Accepted Answer

A)  Na+ concentration outside the cell. 
B)  use of ATP by the sodium-potassium pump. 
C)  permeability of the cell membrane. 
D)  time needed for K+ ions to reach equilibrium. 
E)  extracellular environment.

Question 10

Earthworms and squid have clusters of neurons called

Accepted Answer

A)  ganglia. 
B)  the central nervous system. 
C)  the peripheral nervous system. 
D)  the spinal cord. 
E)  a nerve net.

Question 11

Which statement about microglia is true?

Accepted Answer

A)  They are activated by damage to neural tissue. 
B)  They act as macrophages in the peripheral nervous system. 
C)  They form synapses with brain neurons and conduct action potentials. 
D)  They form myelin sheaths around neurons of the peripheral nervous system. 
E)  They supply neurons of the brain and spinal cord with nutrients.

Question 12

Which statement about the knee-jerk reflex is true?

Accepted Answer

A)  It requires a decision to move the leg. 
B)  It requires stretch receptors that fire action potentials in motor neurons. 
C)  It involves motor neurons conducting action potentials to the leg muscles. 
D)  It requires interneurons carrying signals to the brain. 
E)  It involves output leaving the dorsal horn of the spinal cord.

Question 13

What type of synapse is the neuromuscular junction?

Accepted Answer

A)  Mechanically gated synapse 
B)  Chemical synapse 
C)  Electrical synapse 
D)  Bidirectional synapse 
E)  Synapse in which connexins link the neuron and its target cell

Question 14

In vertebrates, most cells of the nervous system are found in the

Accepted Answer

A)  peripheral nervous system. 
B)  central nervous system. 
C)  spinal reflex system. 
D)  nerve net. 
E)  spinal column.

Question 15

Ion transporters and ion channels both contribute to membrane potentials but differ in their requirement for

Accepted Answer

A)  antiporters. 
B)  Na+ ions. 
C)  K+ ions. 
D)  energy. 
E)  myelin.

Question 16

The neurons involved in a polysynaptic reflex such as the withdrawal reflex are an afferent neuron, an efferent neuron, and _______.

Accepted Answer

The answer of The neurons involved in a polysynaptic reflex...

Question 17

The tripartite synapse model describes the arrangement of _______, _______, and _______.

Accepted Answer

A)  cell bodies; axons; axon terminals 
B)  presynaptic neurons; postsynaptic neurons; astrocytes 
C)  dendrites; cell bodies; axons 
D)  neurons; macroglia; microglia 
E)  presynaptic neurons; axon terminals; postsynaptic neurons

Question 18

Action potentials cannot propagate under myelin sheaths because there are no sodium or _______ channels.

Accepted Answer

The answer of Action potentials cannot propagate under myelin sheaths...

Question 19

To maintain the resting potential of the nerve cell membrane, the sodium‒potassium pump keeps the concentration of

Accepted Answer

A)  K+ and Na+ inside the cell lower than in the extracellular fluid. 
B)  Na+ inside the cell greater than outside the cell, and that of K+ inside the cell lower than outside the cell. 
C)  K+ inside the cell greater than in the extracellular fluid, and that of Na+ inside the cell lower than outside the cell. 
D)  Na+ and K+ inside the cell greater than outside the cell. 
E)  negative ions higher inside the cell by pumping negative ions across the membrane.

Question 20

Following the spike of an action potential, the return to resting membrane potential is facilitated by

Accepted Answer

A)  Na+ ions moving into the cell through open Na+ channels. 
B)  K+ ions moving into the cell through K+ channels. 
C)  the closing of Cl- ion channels. 
D)  inactivation of leak channels. 
E)  the opening of voltage-gated K+ channels.

Exam 44: Neurons, Glia, and Nervous Systems