A&P Chapter 12: Nervous System: Nervous Tissue

______ are released from neurons in response to conductive activity.

neurotransmitters

Choose the cells that are part of the central nervous system.

oligodendrocyte ependymal cells microglia astrocyte

____ are large cells that ensheath many different axons.

oligodendrocytes

Which of the following would be likely to cause hyperpolarization of a neuron?

opening of a chemically gated chloride channel opening of a voltage-gated potassium channel

Which of the following would be likely to cause depolarization of a neuron?

opening of a chemically gated sodium channel opening of a voltage-gated sodium channel

A nerve is part of the ______ nervous system.

peripheral

Clusters of neuron cell bodies called ganglia are found in the ______ nervous system.

peripheral

Voltage is a measure of relative ____ energy.

potential

______ is the return of polarity from positive back to negative (the RMP).

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

The removal of neurotransmitters from the synaptic cleft by transport into the synaptic knob is known as ______.

reuptake

Dendrites are ______ than axons.

shorter

Glial cells are ______ than neurons.

smaller

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

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

The myelin sheath covers ______.

the axon

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

threshold; -55mV

True or false: Voltage-gated sodium ion channels are closed initially and the membrane potential is -70 mv.

true

Most sensory neurons are ______.

unipolar

Pseudounipolar is another name for a ______ neuron

unipolar

There are ______ different types of glial cells in the CNS.

4

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

Ca2+ Na+/K+

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+

Which describes the propagation of depolarization down an axon?

The flow of Na+ to downstream regions causes depolarization of adjacent regions.

Membrane pumps require ______ energy.

a lot of

Sensory ______ neurons carry information ______ the central nervous system.

afferent; toward

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

amplitude; frequency

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

anterograde

The voltage-gated sodium channels ______ during repolarization.

are inactivated

The voltage-gated potassium channels ______ during repolarization.

are open

Which glial cell occupies the space of dying neurons?

astrocytes

______ are star shaped.

astrocytes

The plasma membrane of an axon is called the

axolemma

Cytoplasm within an axon is called ______.

axoplasm

Unipolar neurons start out as ______ neurons during development.

bipolar

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 nucleus of a neuron is found in the ______ of the neuron.

cell body

Most synapses in the human body are ______ synapses.

chemical

The total length of the axon is called the ____ segment.

conductive

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

conductive segment

Glial cells ______ transmit electrical impulses.

do not

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

electrical

Synapses are classified as ______.

electrical synapses and chemical synapses

The choroid plexus is made from capillaries and ______.

ependymal cells

The lining ventricles of the brain is a location of ______.

ependymal cells

What are the characteristics of a neuron?

excitability, conductivity, secretion, extreme longevity, amitotic

True or false: A neuromodulator is another name for a neurotransmitter.

false

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

faster

A motor neuron is a ______ classification of a neuron.

functional

Match the neurotransmitter to its class.

glutamate - amino acid norepinephrine - monoamine

Match the neurotransmitter with its correct class. Instructions

glycine - amino acid dopamine - monoamine neuropeptide - enkephalin

The event that occurs when the inside of a cell becomes more negative than the resting membrane potential is called

hyperpolarization

Neuronal pools are made of ______.

interneurons

Which of the following are functional classes of neurons?

interneurons, sensory neurons, motor neurons

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

lipids

Cells that wander through the CNS and replicate in response to infection are called

microglia

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

more intense

If a neuron has many dendrites and a single axon, it is called a(n) ______ neuron.

multipolar

Most motor neurons are ______.

multipolar

______ neurons are most common.

multipolar

Oligodendrocytes create the ____ sheath in the central nervous system.

myelin

The ability to alter the response of neurons to neurotransmitters is known as

neuromodulation

Nervous tissue is composed of glial cells and

neurons

Place the events of an EPSP in order.

1. Excitatory neurotransmitter binds to chemically gated cation channel 2. More Na+ enters the postsynaptic cell than K+ leaves 3. The inside of the cell becomes more positive 4. The local current of Na+ becomes weaker as it moves towards the axon hillock

The voltage-gated sodium channels undergo changes in activity during the depolarization phase of an action potential. Place these in order from first to last.

1. The membrane potential is -70 mv. 2. Sodium ions flow into the neuron. 3. The membrane potential becomes more positive. 4. Voltage-gated sodium ion channels open.

Neuronal pools are also called ______.

Pathways and neuronal circuits

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

an increase

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+

A positive change in the membrane potential is called ______.

depolarization

The event that occurs when the inside of the cell becomes more positive (less negative) than the resting membrane potential is called

depolarization

Another way for the neurotransmitter to be removed from the synaptic cleft is by ______ where there is uptake by surrounding glial cells.

diffusion

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

electrical gradiant

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 ____ potential.

graded

Immediately following the repolarization of an action potential, the membrane undergoes ____ before returning to the resting membrane potential.

hyperpolarization

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

inside; outside

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

______ act as phagocytes.

microglial cells

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

myelin

Another name for axon is ______.

nerve fiber

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

nerve impulse

Neuromodulation alters the response of ______ to neurotransmitters.

neurons

The neuron cell body houses both the ______ and the cytoplasm.

nucleus

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

potassium

Propagation of depolarization only flows away from the cell body towards the synaptic knob because ______.

previous regions in the axon have sodium channels in the inactive state

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

pumps

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

sodium

A damaged axon within the PNS can regenerate if ______.

some neurilemma remains

The two factors that affect PNS regeneration are ______.

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

Dendrites transfer information ___ the cell body.

toward

In retrograde transport, substances are moved ______ 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

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.

-70; -55