A&p Chapter 12

Front 1

The effect of a nerve impulse on a postsynaptic neuron depends on_______ (3 things)

Back 1

1) Quantity of neurotransmitter released

2) Characteristics of the receptor on the postsynaptic neuron

3) Kind of neurotransmitter released by the presynaptic neuron

Front 2

Opioids relieve pain by blocking the release of

Back 2

Substance P

Front 3

The membranes of neurons at rest are very permeable to what?

Back 3

K+

Front 4

The membranes at rest are only slightly permeable to what?

Back 4

Na+

Front 5

*Moving more K+ out of the cell then the Na+ that's moving into the cell helps to establish what?

Back 5

Negative resting membrane

Front 6

During depolarization, which gradient(s) move(s) Na+ into the cell?

Back 6

Both the electrical and chemical gradients

Front 7

*Why would a positive ion be driven into a cell?

Back 7

Because the inside of the cell is negative compared to the outside of the cell.

Front 8

*Why would Na+ be driven into a cell?

Back 8

Because the concentration of Na+ is greater outside of the cell.

Front 9

What is the resting membrane potential for most neurons?

Back 9

-70 mV

Front 10

*What does the resting membrane potential for neurons depend on?

Back 10

The distribution of both Na+ and K+ across the cell membrane

Front 11

*Why is the resting membrane potential is closer to the equilibrium potential of K+?

Back 11

Because the cell is more permeable to K+

Front 12

The Na+-K+ pump actively transport both sodium and potassium ions across the membrane to compensate for their constant leakage. In Which direction is each ion pumped?

Back 12

Na+ is pumped out of the cell and K+ is pumped into the cell

Front 13

*In the Na+-K+ pump what does the Na+ pump out agaist?

Back 13

Its electrochemical gradient

Front 14

*In the Na+-K+ pump what does the K+ pump in against?

Back 14

Its concentration gradient

Front 15

The concentrations of which two ions are highest outside the cell.

Back 15

Na+ and Cl-

Front 16

What is occurring in the area between #2 and #3?

Back 16

Sodium ions are entering the axon and causing depolarization

Front 17

The afferent division of the PNS

Back 17

Carries sensory information

Front 18

The small space between the sending neuron and the receiving neuron is the

Back 18

Synaptic cleft

Front 19

A molecule that carries information across the synaptic cleft is a

Back 19

neurotransmitter

Front 20

When calcium ions enter the synaptic terminal

Back 20

they cause vesicles containing neurotransmitter molecules to fuse with the plasma membrane of the sending neuron

Front 21

When the neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron

Back 21

ion channels in the plasma membrane of the receiving neuron open

Front 22

If a signal from a sending neuron makes the receiving neuron more negative inside

Back 22

the receiving neuron is less likely to generate an action potential

Front 23

Which component is usually absent from a neuron?

Back 23

Centrioles

Front 24

Which of the is not a neuron structural category?

Back 24

Pseudopolar

Front 25

*Name three neuron structural categories.

Back 25

1) Multipolar

2) Unipolar

3) Bipolar

Front 26

Neuroglia perform all of these functions except

Back 26

Release neurotransmitters

Front 27

*Name 3 functions of Neuroglia

Back 27

1) Regulate extracellular fluid compostition

2) Secret CSF

3) Provide supportive frameword

Front 28

First event at a synapse

Back 28

An Action Potential arrives at the synaptic terminal

Front 29

Second event at a synapse

Back 29

Calcium channels open, and calcium ions enter the synaptic terminal.

Front 30

Third event at a synapse

Back 30

Vesicles containing neurotransmitter fuse with the plasma membrane of the sending neuron

Front 31

Fourth even at a synapse

Back 31

Neurotransmitter molecules diffuse across the synaptic cleft.

Front 32

Fifth event at a synapse

Back 32

The neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron, causing ion channels there to open

Front 33

If a nerve cell receive many IPSPs at the same time,

Back 33

it will show temporal summation

Front 34

Which cell is indicated by the arrow?

Back 34

Oligodendrocyte

Front 35

*What functions to sheath certain axons of the central nervous system (CNS)?

Back 35

The oligodendrocyte

Front 36

When is the neuron in the relative refractory period?

Back 36

4

Front 37

The neuroglial cells that participate in maintaing the blood-brain barrier are the

Back 37

Astrocytes

Front 38

What type of conduction takes place in unmyelinated axons?

Back 38

Continuous condution

Front 39

*An action potential potential is conducted ____________ along an unmuelinated axon from its _______ _______ to the ____ _________.

Back 39

Continuously,

initial segment,

axon terminals

Front 40

*Can action potential be regenerated at the nodes of Ranvier?

Back 40

No

Front 41

*Action potential is regenerated when voltage-gated ___ channels open in every consecutive segment of the ____.

Back 41

Na+,

Axon

Front 42

An action potential is self-regenerating because

Back 42

depolarizing currents established by the influx of Na+ flow down the axon and trigger an action potential at the next segment

Front 43

* ___ diffusing into the axon during the _____ phase of the action potential creates ____________ current that brings the next segment, or ____, of the axon to the threshold.

Back 43

Na+,

First,

depolarizing,

node

Front 44

Why does regeneration of the action potential occur in one direction, rather than two directions?

Back 44

The inactivation gates of voltage-gated Na+ channels close in the node, or segment, that has just fired an action potential.

Front 45

*At the peak of what phase of the action potential do the inactivation gates close?

Back 45

Depolarization

Front 46

*When the inactivation gates close, what channels become absolutely refractory to another depolarizing stimulus?

Back 46

Voltage-gated Na+

Front 47

What is the function of the myelin sheath?

Back 47

It increases the speed of action potential conduction from the initial segment to the axon terminals.

Front 48

*What increases the velocity of conduction by two mechanisms?

Back 48

Myelin Sheath

Front 49

*First myelin _________ the axon, ________ the loss of depolarizing current across the plasma membrane.

Back 49

insulates,

reducing

Front 50

*Second, the myelin insulation allows _______ across the membrane to change much ______.

Back 50

voltage,

faster

Front 51

*Because of the two myelin mechanisms, ____________ only needs to happen at he widely spaced _____ __ _______, so the action potential appears to ____.

Back 51

regeneration,

nodes of Ranvier,

jump

Front 52

What changes occur to voltage-gated Na+ and K+ channels at the peak of depolarization?

Back 52

Inactivation gates of voltage_gates Na+ channels close, while activation gates at the voltage-gated K+ channels open

Front 53

*Closing of voltage-gated channels is dependent on what?

Back 53

Time

Front 54

In which type of axon will velocity of action potential conduction be the fastest?

Back 54

Myelinated axons with the largest diameter

Front 55

*The large diameter facilitates the flow of depolarizing current through the __________.

Back 55

Cytoplasm