Chapter 12 SB

The sequential opening of voltage-gated sodium channels is followed by the sequential opening of voltage-gated

potassium

Voltage represents ______ energy.

potential

Membrane molecules that use the energy of ATP to move ions against a concentration gradient are called

pumps/proteins

The functions of astrocytes are to ______.

regulate the composition of interstitial fluid assist neuronal development help form the blood-brain barrier

A return of the membrane potential towards the resting membrane potential immediately the following depolarization is called ______.

repolarization

The function of a neuron is dependent on ______.

resting membrane potentials changing

Na+ and K+ leak channels and Na+/K+ pumps on the neuron are responsible for establishing and maintaining the ______ membrane ________

resting, potential

Glial cells are ______ than neurons.

smaller

The flow of ______ ion is the most common cause of depolarization.

sodium

Which of the following membrane transporters are present throughout the membrane of a neuron?

sodium leak channels potassium leak channels Na+/K+ pumps

A damaged axon within the PNS can regenerate if ______.

some neurilemma remains

"An action potential either happens or it doesn't." This statement could also be called ______.

the all-or-none law

The two factors that affect PNS regeneration are ______.

the amount of damage and the distance between the injury site and the effector organ

The all-or-none law refers to the fact that action potentials will only occur if the initial segment reaches

threshold

The conductive segment of a neuron is/are the ______.

total length of the axon

In retrograde transport, substances are moved ______ the cell body.

toward

Vesicles involved in retrograde transport are moving ______ the cell body.

toward

True or false: Graded potentials vary in size depending on the stimulus.

true

The measure of the difference in electrical charge between two areas is called a

voltage

If a subthreshold value is reached on an axon membrane, an action potential ______.

will not occur

Match the structure with the appropriate letter in the given image of a neuron.

A. dendrites B. axon C. axon collateral D. terminal extensions

Match the structure with the appropriate letter in the illustration of a neuron.

A. nucleolus B. cell body C. neurolemmocyte D. node

______ are star shaped.

Astrocytes

Which of the following pumps can you find in the plasma membrane?

Ca2+ Na+/K+

Most synapses in the human body are ______ synapses.

Chemical

______ is responsiveness to a stimuli.

Excitability

Repolarization is due to the opening of voltage-gated _______ and the subsequent movement of _____ out of the cell.

K+/K+

The threshold is reached when the ______ ions flow into the cell.

Na+

The nerve impulse has the voltage-gated ______ channels opened first followed by the opening of the voltage-gated ______ channels.

Na+; K+

______ are released from neurons in response to conductive activity.

Neurotransmitters

Place the events of an EPSP in order.

The excitatory neurotransmitter binds to the chemically gated cation channel. More Na+ enters the postsynaptic cell than K+ leaves. The inside of the cell becomes more positive. The local current of Na+ becomes weaker as it moves towards the axon hillock.

Membrane pumps require ______ energy.

a lot

Action potentials are always propagated along an axon at the same ______ but ______ can vary depending on the strength of the stimulus.

amplitude; frequency

The nerve impulse causes ______ in the number of calcium ions that enter the synaptic knob.

an increase

A substance synthesized at the cell body must undergo ______ transport to reach the synaptic knobs.

anterograde

Which glial cell occupies the space of dying neurons?

astrocytes

The myelin sheath covers ______.

axon

A nerve is a bundle of parallel

axons

Many excitatory neurotransmitters cause the opening of channels that allow for the flow of ______.

both Na+ and K+

Which are components of the central nervous system?

brain and spinal cord

The presence of ______ ions causes the synaptic vesicles to bind to the membrane, allowing neurotransmitters to be released.

calcium

The brain and spinal cord are part of the ______.

central nervous system

Synapses are classified as ______.

chemical synapses and electrical synapses

The main activity of the ______ is the propagation of an action potential along the axolemma.

conductive segment

The total length of the axon is called the

conductive segment

The electrical gradient in a resting neuron is such that the ______ of the cell is negative relative to the ______.

cytosol; interstitial

A positive change in the membrane potential is called ______.

depolarization

Creating and transmitting ___________ currents is central to the function of neuron physiology

electrical

A difference in the number of charged particles between two sides of the membrane forms a(n) ______.

electrical gradient

A larger axon transmits an impulse ______ than a smaller axon.

faster

A potential that is a temporary change in membrane potential which lasts only as long as the stimulus that causes it and can vary in size is called a

graded potential

Glial cells are found ______.

in both the central and peripheral nervous system

During an action potential, voltage-gated potassium channels open after voltage-gated sodium channels. The effect this has on the membrane potential is ______.

it becomes less positive and more negative

The myelin sheath is made of a high percentage of ______.

lipids

The brain interprets the increased frequency of nerve signals as a ______ stimulus.

more intense

Most motor neurons are ______.

multipolar

The presence of a ___ sheath increases the rate of impulse conduction.

myelin

A cable like bundle of axons in the peripheral nervous system is called a ______.

nerve

A ______ is the propagation of an action potential along an axon.

nerve impulse

What is the primary tissue of the nervous system?

nervous tissue

Nervous tissue is composed of glial cells and

neurons

The components of nervous tissue that conduct electrical impulses are ______.

neurons

Initially, the voltage-gated Na+ channels are closed and the membrane potential is ______ mV. As Na+ flows in the membrane potential changes to ______ mV and the threshold is reached. Multiple choice question. -70; -90

-70; -55