PNB 2264: Neurophysiology, skeletal
muscle, brain and physiology practice
questions Study Guide Exam and
Actual Answers.
dendrite - Answer What part of the neuron is this?
node of ranvier - Answer What part of the neuron is this?
cell body (soma) - Answer What part of the neuron is this?
axon terminal - Answer What part of the neuron is this?
myelin sheath - Answer What part of the neuron is this?
What is the function of the dendrite? - Answer The dendrites are a place of signal input to
the neuron. They contain high densities of receptors because they are constantly receiving
signals from internal and external environment.
What is the function of the soma (cell body)? - Answer Signal integration and other cellular
functions
What is the function of the axon hillock? - Answer It is where the action potential is
generated and spreads through the axon into the axon terminal
What is the function of the axon terminal? - Answer Forms synapses or connections with
other cell types (neurons or non neuronal cell types inside the body)
What is a synapse? - Answer Point of communication between two different cells.
What is the term for the phase when a membrane at rest experiences a positive change in
membrane potential? - Answer Depolarization
What is the term for the phase when a membrane returns to rest from depolarization? - Answer
Repolarization
,What is the term for when a membrane at rest experiences a negative charge in membrane
potential? - Answer Hyperpolarization
What type of graded potential describes a positive or depolarizing change from rest? What is an
example of this potential? - Answer Excitatory postsynaptic potential (EPSP)
Example is opening a sodium channel.
These push the neuron closer to threshold and make an action potential more likely.
What type of potential describes any negative or hyperpolarizing change from rest? What is an
example of this potential? - Answer Inhibitory postsynaptic potential (IPSP)
Example is
opening up a potassium channel
These push the neuron further from threshold and make an action potential harder to achieve.
What is the difference between a graded potential and an action potential? - Answer Action
potentials are able to maintain their strength over time and distance, whereas a graded
potential decreases over time and distance
Explain what a passive electrical signal is and give an example. - Answer Passive electrical
signals are transient changes in the membrane potential that is specific to one region of the cell
and only occurs for a short period of time
Examples would be graded potentials and synaptic potentials
Explain what an active electrical signal is and give an example. - Answer Active electrical
signals create changes in membrane potential that can spread over a very long distance
An example would be an action potential
Describe a typical axon segment - Answer An axon is separated into segments that are like
work stations. Each of them have what they need (coltage gated Na+ channels) to create action
potential in that spot. The action potential needs to be able to travel all the way from the axon
hillock to the axon terminal. It's easier for the action potential to travel from one segment to the
next than all the way through (in the same way we take breaks between sets at the gym).
How does myelin increase the speed of an action potential? - Answer Think of it like an
electrical cord. If you have holes in the rubber around the wires your device is going to charge
slower or not at all. It acts as a insulating wrapper that keeps local currents from dissipating into
external environments. It creates an increase in conduction velocity and efficiency of the overall
neuron.
What is a myelinated segment called? - Answer Internode
, What is a non myelinated segment called? - Answer Node of ranvier
What are the characteristics of nervous tissue? - Answer High metabolic rate: Nervous
system depends on concentration gradients which means neurons must have a very high
capacity to generate apt to keep the ions in and out of the cell within homeostatic ranges
Extreme longevity:
they live longer than other cells in the body
Non-mitotic
Terminally differentiated cell that does not go through mitosis.
We can replace neurons but we have to go through the stem cell differentiation process.
We normally can't get the neurons to differentiate in the right spot which makes it hard to treat
neurodegenerative diseases.
Where is action potential initiated and why? - Answer Action potential is initiated at the axon
hillock.
It starts here because there is a high density of voltage gated sodium channels
How do changes in ion concentration impact action potential? - Answer The depolarization
associated with an action potential generated at one point along an axon spreads passively to
the adjacent segment, where it triggers opening of voltage-gated Na+ channels and hence
another action potential. Propagation of the action potential occurs in one direction only
because of the short inactive period of the Na+ channels and the brief hyperpolarization
resulting from K+ efflux
How does a change in permeability impact the membrane potential - Answer An increase in
sodium permeability correlates with depolarization which will lead to an ever greater number of
Na+ channels opening and membrane potential becoming even more depolarized.
What is an inactive state? - Answer think of a house with a screen door and a glass door. One
of them is open but the other door is still closed. Sodium still cannot enter the cell because one
of the doors is closed.
What is an open state? - Answer An open state is when the activation gate and the
inactivation gate are open
What is a closed state? - Answer A closed state is when the activation gate is closed but the
inactivation gate is still open.
What are the effects of channelopathies on nervous system function?
muscle, brain and physiology practice
questions Study Guide Exam and
Actual Answers.
dendrite - Answer What part of the neuron is this?
node of ranvier - Answer What part of the neuron is this?
cell body (soma) - Answer What part of the neuron is this?
axon terminal - Answer What part of the neuron is this?
myelin sheath - Answer What part of the neuron is this?
What is the function of the dendrite? - Answer The dendrites are a place of signal input to
the neuron. They contain high densities of receptors because they are constantly receiving
signals from internal and external environment.
What is the function of the soma (cell body)? - Answer Signal integration and other cellular
functions
What is the function of the axon hillock? - Answer It is where the action potential is
generated and spreads through the axon into the axon terminal
What is the function of the axon terminal? - Answer Forms synapses or connections with
other cell types (neurons or non neuronal cell types inside the body)
What is a synapse? - Answer Point of communication between two different cells.
What is the term for the phase when a membrane at rest experiences a positive change in
membrane potential? - Answer Depolarization
What is the term for the phase when a membrane returns to rest from depolarization? - Answer
Repolarization
,What is the term for when a membrane at rest experiences a negative charge in membrane
potential? - Answer Hyperpolarization
What type of graded potential describes a positive or depolarizing change from rest? What is an
example of this potential? - Answer Excitatory postsynaptic potential (EPSP)
Example is opening a sodium channel.
These push the neuron closer to threshold and make an action potential more likely.
What type of potential describes any negative or hyperpolarizing change from rest? What is an
example of this potential? - Answer Inhibitory postsynaptic potential (IPSP)
Example is
opening up a potassium channel
These push the neuron further from threshold and make an action potential harder to achieve.
What is the difference between a graded potential and an action potential? - Answer Action
potentials are able to maintain their strength over time and distance, whereas a graded
potential decreases over time and distance
Explain what a passive electrical signal is and give an example. - Answer Passive electrical
signals are transient changes in the membrane potential that is specific to one region of the cell
and only occurs for a short period of time
Examples would be graded potentials and synaptic potentials
Explain what an active electrical signal is and give an example. - Answer Active electrical
signals create changes in membrane potential that can spread over a very long distance
An example would be an action potential
Describe a typical axon segment - Answer An axon is separated into segments that are like
work stations. Each of them have what they need (coltage gated Na+ channels) to create action
potential in that spot. The action potential needs to be able to travel all the way from the axon
hillock to the axon terminal. It's easier for the action potential to travel from one segment to the
next than all the way through (in the same way we take breaks between sets at the gym).
How does myelin increase the speed of an action potential? - Answer Think of it like an
electrical cord. If you have holes in the rubber around the wires your device is going to charge
slower or not at all. It acts as a insulating wrapper that keeps local currents from dissipating into
external environments. It creates an increase in conduction velocity and efficiency of the overall
neuron.
What is a myelinated segment called? - Answer Internode
, What is a non myelinated segment called? - Answer Node of ranvier
What are the characteristics of nervous tissue? - Answer High metabolic rate: Nervous
system depends on concentration gradients which means neurons must have a very high
capacity to generate apt to keep the ions in and out of the cell within homeostatic ranges
Extreme longevity:
they live longer than other cells in the body
Non-mitotic
Terminally differentiated cell that does not go through mitosis.
We can replace neurons but we have to go through the stem cell differentiation process.
We normally can't get the neurons to differentiate in the right spot which makes it hard to treat
neurodegenerative diseases.
Where is action potential initiated and why? - Answer Action potential is initiated at the axon
hillock.
It starts here because there is a high density of voltage gated sodium channels
How do changes in ion concentration impact action potential? - Answer The depolarization
associated with an action potential generated at one point along an axon spreads passively to
the adjacent segment, where it triggers opening of voltage-gated Na+ channels and hence
another action potential. Propagation of the action potential occurs in one direction only
because of the short inactive period of the Na+ channels and the brief hyperpolarization
resulting from K+ efflux
How does a change in permeability impact the membrane potential - Answer An increase in
sodium permeability correlates with depolarization which will lead to an ever greater number of
Na+ channels opening and membrane potential becoming even more depolarized.
What is an inactive state? - Answer think of a house with a screen door and a glass door. One
of them is open but the other door is still closed. Sodium still cannot enter the cell because one
of the doors is closed.
What is an open state? - Answer An open state is when the activation gate and the
inactivation gate are open
What is a closed state? - Answer A closed state is when the activation gate is closed but the
inactivation gate is still open.
What are the effects of channelopathies on nervous system function?
