Question 1

____________________ are local chemical messengers that exert an effect only on neighboring cells in the immediate environment.

Accepted Answer

The answer of ____________________ are local chemical messengers that exert...

Question 2

Indicate the relationship between the two items listed in each situation:
a.A is greater than b.
b.B is greater than a.
c.A and B are equal.
-a.Neuron's permeability to Na⁺ during the falling phase of an action potential
B.Neuron's permeability to K⁺ during the falling phase of an action potential

Accepted Answer

The answer of Indicate the relationship between the two items...

Question 3

Use these figures to answer the corresponding questions.
-The structure labeled "4" is
a.part of a channel that allows Na+ ions to diffuse into the ECF
b.the activation gate for a gated K+ channel
c.the inactivation gate for a gated Na+ channel
d.part of a second messenger system
e.the activation gate for a gated K+ channel and part of a second messenger system

Accepted Answer

The answer of  
Use these figures to answer the...

Question 4

A threshold potential is

Accepted Answer

A) the potential achieved when two opposing forces acting upon an ion (concentration and electrical gradients) achieve a state of equilibrium 
B) the peak potential achieved during an action potential 
C) the point at which there is an explosive increase in Na+ or Ca₂₊ permeability 
D) the potential at which K+ permeability increases 
E) always a positive potential

Question 5

Thyroid hormone is derived from an amino acid, which makes it soluble in water and able to utilize a second messenger system.

Accepted Answer

A) True 
 B)False

Question 6

The trigger zone of a neuron

Accepted Answer

A) is located at the axon hillock 
B) is located in the axon terminal 
C) contains only chemically gated channels 
D) conducts graded potentials to the axon 
E) causes action potentials to move toward the cell body and dendrites

Question 7

____________________ move through the axon before being released from the synaptic knob and then bind to nonsynaptic receptors; whereas, ____________________ are made in the cytosol of the synaptic knob and after their release bind to subsynaptic receptors.

Accepted Answer

The answer of ____________________ move through the axon before being...

Question 8

The Na⁺ and K⁺ channels that open and close during an action potential are voltage-gated channels.

Accepted Answer

A) True 
 B)False

Question 9

Which of the following is responsible for the falling phase of an action potential?

Accepted Answer

A) opening of Na+ gates 
B) Na+-K+ pump restoring the ions to their original locations 
C) greatly increased permeability to Na+ 
D) Na+ efflux 
E) none of these

Question 10

Use this figure to answer the corresponding questions.
-A second messenger is labeled
a.1
b.2
c.3
d.4
e.5

Accepted Answer

The answer of  
Use this figure to answer the...

Question 11

A given synapse may produce EPSPs at one time and IPSPs at another time.

Accepted Answer

A) True 
 B)False

Question 12

Tetanus toxin

Accepted Answer

A) binds with glycine receptors, thus blocking the action of this inhibitory neurotransmitter 
B) destroys dopamine in the region of the brain involved in controlling complex movements 
C) prevents the release of GABA that inhibits neurons that innervate skeletal muscle cells 
D) promotes presynaptic facilitation 
E) causes IPSPs to occur on skeletal muscle cell membranes

Question 13

At an inhibitory synapse, the postsynaptic membrane experiences

Accepted Answer

A) an increase in permeability to both Na+ and K+ 
B) an increase in membrane potential 
C) hyperpolarization 
D) an influx of cations 
E) all of the above

Question 14

Because of the presence of both activation and inactivation gates, voltage-gated Na⁺ channels can

Accepted Answer

A) be closed but capable of opening 
B) be activated 
C) be closed and not capable of opening 
D) exhibit all of the above events 
E) exhibit only the a and b events

Question 15

Myelinated fibers conduct impulses about ____________________ times faster than unmyelinated fibers of the same diameter.

Accepted Answer

The answer of Myelinated fibers conduct impulses about ____________________ times...

Question 16

Which of the following is not a graded potential?

Accepted Answer

A) end-plate potential 
B) action potential 
C) slow-wave potential 
D) receptor potential 
E) postsynaptic potential

Question 17

Indicate which of the following changes will take place.
a.no change in potential of the postsynaptic cell
b.spatial summation
c.temporal summation
-What would occur if presynaptic neuron B were fired rapidly?

Accepted Answer

The answer of Indicate which of the following changes will...

Question 18

If neuron X causes hyperpolarization, then what does it cause in a postsynaptic neuron?

Accepted Answer

A) Increased PNa+ and PK+ 
B) Increased PK+ or PCl- 
C) Increased influx of protein anions 
D) Increased permeability to calcium ions 
E) Either b or c

Question 19

Which statement is incorrect?

Accepted Answer

A) Inhibitory synapses cause postsynaptic hyperpolarization. 
B) An inhibitory synapse may result in postsynaptic sodium channel opening. 
C) An inhibitory synapse may result in increased postsynaptic potassium efflux. 
D) An excitatory synapse causes depolarization of postsynaptic membranes. 
E) An excitatory synapse increases sodium permeability.

Question 20

____________________ cells form myelin around neurons in the PNS, whereas ____________________ form myelin around neurons in the CNS.

Accepted Answer

The answer of ____________________ cells form myelin around neurons in...

Exam 4: Principles of Neural and Hormonal Communication

____________________ are local chemical messengers that exert an effect only on neighboring cells in the immediate environment.

A threshold potential is

Thyroid hormone is derived from an amino acid, which makes it soluble in water and able to utilize a second messenger system.

The trigger zone of a neuron

move through the axon before being released from the synaptic knob and then bind to nonsynaptic receptors; whereas, are made in the cytosol of the synaptic knob and after their release bind to subsynaptic receptors.

The Na⁺ and K⁺ channels that open and close during an action potential are voltage-gated channels.

Which of the following is responsible for the falling phase of an action potential?

Use this figure to answer the corresponding questions. -A second messenger is labeled a.1 b.2 c.3 d.4 e.5

A given synapse may produce EPSPs at one time and IPSPs at another time.

Tetanus toxin

At an inhibitory synapse, the postsynaptic membrane experiences

Because of the presence of both activation and inactivation gates, voltage-gated Na⁺ channels can

Myelinated fibers conduct impulses about ____________________ times faster than unmyelinated fibers of the same diameter.

Which of the following is not a graded potential?

Indicate which of the following changes will take place. a.no change in potential of the postsynaptic cell b.spatial summation c.temporal summation -What would occur if presynaptic neuron B were fired rapidly?

If neuron X causes hyperpolarization, then what does it cause in a postsynaptic neuron?

Which statement is incorrect?

cells form myelin around neurons in the PNS, whereas form myelin around neurons in the CNS.