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Example Questions
Example Question #2 : General Neuron Physiology
Which of the following is responsible for opening sodium channels in the plasma membrane of the receiving neuron, leading to an action potential or more excitable neuron?
Chloride
Calcium
Norepinephrine
Glutamate
GABA (gamma-aminobutyric acid)
Glutamate
Glutamate opens sodium channels in the plasma membrane of the receiving neuron, moving the action potential towards (depolarize) the sodium Nernst potential (81mV). GABA is an inhibitory neurotransmitter which opens chloride channels in the plasma membrane of the receiving neuron, making the neuron more difficult to excite (hyperpolarized).
Example Question #8 : Neural Physiology
The resting membrane potential (RMP) is primarily determined by which ion?
Calcium
Chloride
Sodium
Magnesium
Potassium
Potassium
The resting membrane potential is based on the difference in electrical charges of the ions that flow through the membrane. The membrane potential has a greater permeability to potassium when at rest which causes a shift in its potential. Thus, potassium has the strongest affect on the RMP and causes it to be closer to potassium's reversal potential. Side note: This potential is strongly held by the sodium potassium pump.
Example Question #171 : Systems Physiology
A stimulus applied to a neuronal membrane that causes its potential to become more positive is __________. A stimulus that moves the potential closer to 0 is __________.
depolarization . . . depolarization
hyperpolarization . . . depolarization
hyperpolarization . . . resting membrane potential
hyperpolarization . . . hyperpolarization
depolarization . . . hyperpolarization
hyperpolarization . . . depolarization
If an already positive membrane potential becomes more positive, it is becoming hyperpolarized because the electrical difference between the inside and outside of the cell is getting larger. On the other hand, a stimulus that moves the potential difference closer to 0 is depolarizing because it is decreasing the difference in electrical potential between the inside and outside of the cell.
Example Question #933 : Human Anatomy And Physiology
The presence of __________ dramatically increases the speed at which an action potential moves along an axon.
plasma protein
a capsule
myelin
neurilemma
myelin
Myelin helps to increase resistance along the axon, which helps to propagate the action potential along the axon.
Example Question #172 : Systems Physiology
The following are the main steps in the generation of an action potential:
1. inactivation of Na channels and activation of K channels
2. depolarization to threshold
3. return to normal permeability
4. activation of Na channels
What is the proper sequence of these events?
4,3,2,1
2,4,3,1
1,2,3,4
2,4,1,3
2,4,1,3
In order to have an action potential, you must have a depolarization. Na channels must close before K channels open
Example Question #13 : Help With Action Potential Physiology
Which part of the neuron generates the action potential?
axon
axon hillock
nucleus
dendrites
cell body
axon hillock
The action potential of a neuron is generate at the axon hillock and is propagated down the axon and to the terminal branches where it will synapse with the dendrites of the next neuron.
Example Question #173 : Systems Physiology
Which of the following describes the influx of ions into the neuron?
repolarization
none of these
polarization
hyperpolarization
depolarization
depolarization
The influx of positive sodium ions into the neuron is known as depolarization. This is the loss of negative charge that occurs when positive sodium passes through the neural membrane and enters the neuron.
Example Question #174 : Systems Physiology
When the neuron becomes depolarized, which of the following events takes place?
efflux of sodium ions
influx of sodium ions
efflux of potassium ions
None of these will occur.
influx of potassium ions
influx of sodium ions
Depolarization is when the neuron becomes more positive by gaining positively charged ions, specifically sodium ions. During depolarization the sodium ion channels open and sodium ions enter the neuron, reducing the membrane potential to roughly +35 mV.
Example Question #175 : Systems Physiology
Which of the following statements is true of a bipolar neuron?
It has two axons branching off of the neuron body
It has two processes extending off of the neuron's cell body
It only communicates with two other neurons
It is the most common neuron type in the brain
It has two processes extending off of the neuron's cell body
There are three possible neural cell structures: unipolar, bipolar, and multipolar. Bipolar neurons have only two extensions coming off of the cell body, typically the dendrite extension and the axon extension. Although there are only two extensions coming off of the neuron, it is still capable of interacting with many other neurons due to subsequent branching beyond the junction with the cell body.
Example Question #176 : Systems Physiology
Which of the following is NOT a property of neurons?
Compose the nervous system
Permanent cells
Cells do not divide during adulthood
Undergo reactive gliosis in response to injury
Undergo reactive gliosis in response to injury
Neurons are the cells that make up the nervous system. Neurons are large, permanent cells that do not divide during adulthood and spend most of their lives in the G0 phase of the cell cycle. If part of a neuron is damaged, it undergoes Wallerian degeneration, meaning that the neuron degenerates distal to the injury, and does not undergo reactive gliosis in response to injury. Astrocytes, a type of glial cell, do this.
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