Nervous System Smartbook
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
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
______ is a type of membrane transport protein that increases the potential energy across a membrane.
A pump
The threshold is reached when the ______ ions flow into the cell.
Na+
Which of the following membrane transporters are present throughout the membrane of a neuron?
Na+/K+ pumps sodium leak channels potassium leak channels
______ are released from neurons in response to conductive activity.
Neurotransmitters
______ is the return of polarity from positive back to negative (the RMP).
Repolarization
______ (is) are the slightly expanded region at the tip of the fine terminal extensions of a neuron.
Synaptic knobs
The refractory period occurs immediately ______ an action potential.
after
An epineurium surrounds ______.
an entire nerve
Neuronal pools are made of ______.
interneurons
A cablelike bundle of axons in the peripheral nervous system is called a ______.
nerve
Another name for axon is ______.
nerve fiber
A ______ is the propagation of an action potential along an axon.
nerve impulse
The thin outer layer of the neurolemmocyte is called the ______.
neurilemma
The ability to alter the response of neurons to neurotransmitters is known as _____.
neuromodulation
A damaged axon within the PNS can regenerate if ______.
some neurilemma remains
Neurons integrate multiple synaptic inputs by the process of ______.
summation
The process by which postsynaptic potentials are added together at the initial segment is known as _____.
summation
"An action potential either happens or it doesn't." This statement could also be called ______.
the all-or-none law
______ is a typical resting membrane potential for a neuron.
-70 millivolts
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. membrane potential is -70 mv 2. sodium ions flow into the neuron 3. membrane potential becomes more positive 4. voltage-gated sodium ion channels open
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+
True or false: A neuromodulator is another name for a neurotransmitter.
False
True or false: Ion channels use the energy of ATP to maintain concentration gradients across neuron membranes.
False
True or false: The relative charge across a neuron's plasma membrane is negative outside the cell relative to the inside of the cell.
False
______ to help return the membrane potential to the resting state following hyperpolarization.
Na+/K+ pumps restore gradients Voltage-gated potassium channels close
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.
True or false: Graded potentials vary in size depending on the stimulus.
True
True or false: Voltage-gated sodium ion channels are closed initially and the membrane potential is -70 mv.
True
______ and are the cause of hyperpolarization in an action potential.
Voltage-gated potassium channels remain open
Membrane pumps require ______ energy.
a lot of
The relative refractory period occurs ______ the absolute refractory period.
after
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
The voltage-gated sodium channels ______ during repolarization.
are inactivated
The voltage-gated potassium channels ______ during repolarization.
are open
The perivascular feet of the ______ help create a blood-brain barrier.
astrocyte
Which glial cell occupies the space of dying neurons?
astrocyte
Choose the cells that are part of the central nervous system.
astrocyte oligodendrocyte microglia ependymal cells
The plasma membrane of an axon is called the _____.
axolemma
The myelin sheath covers ______.
axon
A fascicle is a bundle of ______.
axons
A nerve is a bundle of parallel _____.
axons
Cytoplasm within an axon is called ______.
axoplasm
A synapse is a junction ______.
between a neuron and another cell
Unipolar neurons start out as ______ neurons during development.
bipolar
Many excitatory neurotransmitters cause the opening of channels that allow for the flow of ______.
both Na+ and K+
Identify all of the components of the central nervous system.
brain spinal cord
Which are components of the central nervous system?
brain and spinal cord
The central nervous system is made of the _____ and spinal _____.
brain, cord
The presence of ______ ions causes the synaptic vesicles to bind to the membrane, allowing neurotransmitters to be released.
calcium
Dendrites branch off of the ______.
cell body
Soma is another name for the ______.
cell body
The ______ is the structural division of the nervous system that contains the brain.
central nervous system
The ependymal cells help produce ______.
cerebrospinal fluid
Ependymal cells produce and circulate cerebrospinal fluid. The ______ helps circulate the CSF.
cilia
Ganglia are ______.
clusters of neuron cell bodies
The total length of the axon is called the _____ segment.
conductive
The epineurium is made of ______ connective tissue.
dense irregular
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
Glial cells ______ transmit electrical impulses.
do not
The tissues that receive nerve impulses from motor neurons are called ______.
effectors
Motor neurons are classified as ______ neurons.
efferent
Creating and transmitting _____ currents is central to the function of neuron physiology.
electrical
Synapses are classified as ______.
electrical and chemical
A difference in the number of charged particles between two sides of the membrane forms a(n) ______.
electrical gradient
The lining ventricles of the brain is a location of ______.
ependymal cells
______ is responsiveness to a stimuli.
excitability
Which of the following are characteristics of neurons?
excitability secretion amitotic conductivity extreme longevity
A larger axon transmits an impulse ______ than a smaller axon.
faster
A motor neuron is a ______ classification of a neuron.
functional
Neurons are classified ______ depending on the direction the nerve impulse travels.
functionally
Sensory input and motor output are used to divide the nervous system ______.
functionally
The peripheral nervous system is made of nerves and _____.
ganglia
A cluster of neuron cell bodies found along a peripheral nerve is known as a(n) _____.
ganglion
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
The chromatophilic substance helps create the ______ color in parts of the brain and spinal cord.
gray
Negatively charged proteins and other large organic molecules are found in ______.
greater amounts inside a neuron
Immediately following the repolarization of an action potential, the membrane undergoes _____ before returning to the resting membrane potential.
hyperpolarization
The event that occurs when the inside of a cell becomes more negative than the resting membrane potential is called _____.
hyperpolarization
Glial cells are found ______.
in both the central and peripheral nervous system
The changes in membrane potential associated with both EPSP and IPSP inputs are "added" in the ______ to determine if an action potential is initiated and the threshold is reached.
initial segment
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
The myelin sheath is made of a high percentage of ______.
lipids
It usually takes ______ neurolemmocytes to myelinate one axon.
many
Which glial cells remove debris from damaged or dead nervous tissue?
microglia
______ act as phagocytes.
microglial cells
The resting membrane potential is measured in ______.
millivolts
The brain interprets the increased frequency of nerve signals as a ______ stimulus.
more intense
Which of the following are functional classes of neurons?
motor neurons sensory neurons interneurons
If a neuron has many dendrites and a single axon, it is called a(n) ______ neuron.
multipolar
______ neurons are most common.
multipolar
The presence of a _____ sheath increases the rate of impulse conduction.
myelin
What is found in the ganglia of spinal nerves?
neuron cell bodies
Neuronal pools are also called ______.
neuronal pathways neuronal circuits
Nervous tissue is composed of glial cells and _____.
neurons
Neuromodulation alters the response of ______ to neurotransmitters.
neurons
The components of nervous tissue that conduct electrical impulses are ______.
neurons
The neuron cell body houses both the ______ and the cytoplasm.
nucleus
Which neuroglial cells insulate axons in the central nervous system?
oligodendrocytes
_____ 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 fascicle is surrounded by a layer of dense irregular connective tissue called ______.
perineurium
Clusters of neuron cell bodies called ganglia are found in the ______ nervous system.
peripheral
Spinal nerves are part of the ______ nervous system.
peripheral
The sequential opening of voltage-gated sodium channels is followed by the sequential opening of voltage-gated _____ channels.
potassium
Voltage is a measure of relative _____ energy.
potential
Voltage represents ______ energy.
potential
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
An axon is either incapable of generating an action potential or requires a larger than normal stimulus during the _____ period.
refractory
The functions of astrocytes are to ______.
regulate the composition of interstitial fluid, help form the blood-brain barrier, and assist neuronal development.
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
The relative difference in charge across the plasma membrane of a resting neuron is known as the _____ _____ _____.
resting, membrane, potential
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
Chromatophilic substance and Nissl bodies are both types of _____.
ribosomes
The flow of ______ ion is the most common cause of depolarization.
sodium
The two factors that affect PNS regeneration are ______.
the distance between the injury site and the effector organ the amount of damage
If summated PSPs reach a threshold, an action potential begins first in ______.
the initial segment
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
Dendrites transfer information _____ the cell body.
toward
Vesicles involved in retrograde transport are moving ______ the cell body.
toward
The blood-brain barrier helps protect the brain from ______.
toxins
Most afferent neurons are classified functionally as ______.
unipolar
Most sensory neurons are ______.
unipolar
Pseudounipolar is another name for a ______ neuron
unipolar
The measure of the difference in electrical charge between two areas is called a _____.
voltage
