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