Neural Physiology - Human Anatomy and Physiology
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Which of the following does NOT take place during an action potential?
Which of the following does NOT take place during an action potential?
An action potential across a cell membrane has five phases:
1. The resting membrane potential is a negative membrane potential established by the sodium-potassium pump and maintained by potassium leak channels.
2. Depolarization involves opening of voltage-gated sodium channels and results in a rapid influx of positively-charged sodium ions into the cell, creating a positive membrane potential.
3. Overshoot occurs during the maximal value (peak) of the action potential.
4. Hyperpolarization occurs when sodium channels close and potassium channels open, allowing potassium to leak out the cell, and establishing a negative membrane potential below the resting potential.
5. Repolarization occurs when voltage-gated potassium channels eventually close and the membrane potential returns to the resting value via action of the sodium-potassium pump.
Potentiation refers to the phenomenon when nerves become more effective at transmitting signals due to extensive use of the same pathway.
An action potential across a cell membrane has five phases:
1. The resting membrane potential is a negative membrane potential established by the sodium-potassium pump and maintained by potassium leak channels.
2. Depolarization involves opening of voltage-gated sodium channels and results in a rapid influx of positively-charged sodium ions into the cell, creating a positive membrane potential.
3. Overshoot occurs during the maximal value (peak) of the action potential.
4. Hyperpolarization occurs when sodium channels close and potassium channels open, allowing potassium to leak out the cell, and establishing a negative membrane potential below the resting potential.
5. Repolarization occurs when voltage-gated potassium channels eventually close and the membrane potential returns to the resting value via action of the sodium-potassium pump.
Potentiation refers to the phenomenon when nerves become more effective at transmitting signals due to extensive use of the same pathway.
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What part of the action potential results in the depolarization of the cell?
What part of the action potential results in the depolarization of the cell?
When at rest, the neuron initially has a negative membrane potential. At the beginning of an action potential, voltage-gated sodium channels open, allowing sodium ions to enter the cell. This causes the cell to become positively charged compared to the outside of the cell. This process is called depolarization.
After depolarization occurs, the sodium channels close, initiating the absolute refractory period. Voltage-gated potassium channels then open and potassium ions exit the cell. This results in hyperpolarization and the relative refractory period. The potassium channels then close and the sodium-potassium pump returns the cell to its resting potential by removing sodium and collecting potassium.
When at rest, the neuron initially has a negative membrane potential. At the beginning of an action potential, voltage-gated sodium channels open, allowing sodium ions to enter the cell. This causes the cell to become positively charged compared to the outside of the cell. This process is called depolarization.
After depolarization occurs, the sodium channels close, initiating the absolute refractory period. Voltage-gated potassium channels then open and potassium ions exit the cell. This results in hyperpolarization and the relative refractory period. The potassium channels then close and the sodium-potassium pump returns the cell to its resting potential by removing sodium and collecting potassium.
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Which of the following statements is true concerning the absolute refractory period?
Which of the following statements is true concerning the absolute refractory period?
Once an action potential has been created, the membrane has a period of time during which it cannot be stimulated to create another action potential. The absolute refractory period occurs when the voltage-gated sodium channels initially close. The first gating mechanism of these channels cannot be overcome by an electrical stimulus, and the sodium channels will remain closed even if a large electrical stimulus is present. During this period, even a very large stimulus cannot result in neural depolarization.
Following this, the secondary gating mechanism for the channel becomes active. This mechanism is sensitive to electrical stimuli, but keeps the channels closed when the neuron is at rest. The relative refractory period results when sodium channels are capable of opening, but the cell is hyperpolarized, making it very difficult to initiate a stimulus that reaches the action potential threshold.
Once an action potential has been created, the membrane has a period of time during which it cannot be stimulated to create another action potential. The absolute refractory period occurs when the voltage-gated sodium channels initially close. The first gating mechanism of these channels cannot be overcome by an electrical stimulus, and the sodium channels will remain closed even if a large electrical stimulus is present. During this period, even a very large stimulus cannot result in neural depolarization.
Following this, the secondary gating mechanism for the channel becomes active. This mechanism is sensitive to electrical stimuli, but keeps the channels closed when the neuron is at rest. The relative refractory period results when sodium channels are capable of opening, but the cell is hyperpolarized, making it very difficult to initiate a stimulus that reaches the action potential threshold.
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Which of the following are in the correct order regarding action potentials?
Which of the following are in the correct order regarding action potentials?
The neuron has a resting potential. In its resting state, the neuron has a resting potential with a slightly negative interior compared to the exterior. Sodium ions 
enter the cell and alter the membrane potential. Through voltage-gated channels, 
enters and makes the interior less negative therefore decreasing the membrane potential difference, which is known as depolarization. The membrane potential depolarizes all the way up to the threshold level. After enough 
enters, the threshold membrane potential is reached. This opens more 
channels. An action potential is fired, which means that the depolarization spreads down the neuron's axon. This travels down the entire axon, eventually reaching the dendrite and signaling to other neurons.
The neuron has a resting potential. In its resting state, the neuron has a resting potential with a slightly negative interior compared to the exterior. Sodium ions
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What are the two gates of the voltage-gated 
channels along the axonal plasma membrane?
What are the two gates of the voltage-gated
The voltage-gated 
channels along the axonal plasma membrane open and close in response to changes in voltage, and may exist in three distinct states: deactivated, activated, and inactivated. While the axon is at rest, these channels are said to be deactivated; they are impermeable to sodium ions since their activation gates are closed. Once the neuron gets depolarized to the threshold of the voltage-gated sodium channels, the activation gates open, allowing the influx of sodium down its concentration gradient into the cell. During this time the channels are in their activated state. At the peak of the action potential the activation gates are still open, but the inactivation gates close, stopping the flow of sodium through the channels. The channels are in the inactivated state due to the cell becoming depolarized. Once the membrane potential drops back down towards resting, the inactivation gates open, and the activation gates close, thereby deactivating the channels again, until another action potential depolarizes the membrane.
The voltage-gated
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Which type of signal is transmitted along a neuron?
Which type of signal is transmitted along a neuron?
To support the general function of the nervous system, neurons must communicate within the cell (intracellular signaling) and between other cells (intercellular signaling). In order to achieve long distance and rapid communication, neurons have special abilities for sending electrical signals (action potentials) along axons. This mechanism is called conduction, and it is how the neuron's cell body communicates with its own terminals via the axon. Communication between neurons is achieved at synapses by the process of neurotransmission.
To support the general function of the nervous system, neurons must communicate within the cell (intracellular signaling) and between other cells (intercellular signaling). In order to achieve long distance and rapid communication, neurons have special abilities for sending electrical signals (action potentials) along axons. This mechanism is called conduction, and it is how the neuron's cell body communicates with its own terminals via the axon. Communication between neurons is achieved at synapses by the process of neurotransmission.
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When an action potential occurs, the permeability of __________ across the cell membrane becomes much greater.
When an action potential occurs, the permeability of __________ across the cell membrane becomes much greater.
At resting potential, the cell membrane is about 25 times more permeable to potassium ions than it is to sodium ions. During an action potential, the membrane becomes much more permeable to sodium ions than potassium ions, causing the membrane potential to become more positive, as sodium flows down its concentration gradient into the cell. Note that this concentration gradient is largely set up by the action of the sodium-potassium ATPase, which pumps three sodium ions out of the cell in exchange for two potassium ions into the cell.
At resting potential, the cell membrane is about 25 times more permeable to potassium ions than it is to sodium ions. During an action potential, the membrane becomes much more permeable to sodium ions than potassium ions, causing the membrane potential to become more positive, as sodium flows down its concentration gradient into the cell. Note that this concentration gradient is largely set up by the action of the sodium-potassium ATPase, which pumps three sodium ions out of the cell in exchange for two potassium ions into the cell.
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The junction between the transmitting and receiving neuron is called a(n) __________.
The junction between the transmitting and receiving neuron is called a(n) __________.
A synapse is a specialized junction between cells. It is involved in the integration and converging of signals between neurons. At a synaptic junction, the membranes of the pre- and post- synaptic neurons are separated by a gap called a synaptic cleft, which is the site of neurotransmitter release.
A synapse is a specialized junction between cells. It is involved in the integration and converging of signals between neurons. At a synaptic junction, the membranes of the pre- and post- synaptic neurons are separated by a gap called a synaptic cleft, which is the site of neurotransmitter release.
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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?
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?
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).
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).
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Which part of the neuron generates the action potential?
Which part of the neuron generates the action potential?
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.
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.
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When the neuron becomes depolarized, which of the following events takes place?
When the neuron becomes depolarized, which of the following events takes place?
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.
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.
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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?
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?
In order to have an action potential, you must have a depolarization. Na channels must close before K channels open
In order to have an action potential, you must have a depolarization. Na channels must close before K channels open
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The presence of __________ dramatically increases the speed at which an action potential moves along an axon.
The presence of __________ dramatically increases the speed at which an action potential moves along an axon.
Myelin helps to increase resistance along the axon, which helps to propagate the action potential along the axon.
Myelin helps to increase resistance along the axon, which helps to propagate the action potential along the axon.
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Which of the following describes the influx of 
ions into the neuron?
Which of the following describes the influx of
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.
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.
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The resting membrane potential (RMP) is primarily determined by which ion?
The resting membrane potential (RMP) is primarily determined by which ion?
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.
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.
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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 __________.
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 __________.
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.
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.
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Which section of the ear contains the malleus, incus, and stapes bones?
Which section of the ear contains the malleus, incus, and stapes bones?
Sound vibrations from the air are collected by the outer ear, including the cartilaginous pinna. Air vibrations interface with the tympanic membrane, transferring the vibrations to the bones of the middle ear. These bones interface with the oval window to transfer the vibrations to the fluid of the cochlea found in the inner ear, where nerve endings translate the vibrations into electrical signals.
The malleus, incus, and stapes are the bones of the middle ear and are considered the smallest bones in the human body.
Sound vibrations from the air are collected by the outer ear, including the cartilaginous pinna. Air vibrations interface with the tympanic membrane, transferring the vibrations to the bones of the middle ear. These bones interface with the oval window to transfer the vibrations to the fluid of the cochlea found in the inner ear, where nerve endings translate the vibrations into electrical signals.
The malleus, incus, and stapes are the bones of the middle ear and are considered the smallest bones in the human body.
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Which of these correctly traces the transmission of sound from the external environment to the nerves that carry the signal to the brain to be interpreted.
Which of these correctly traces the transmission of sound from the external environment to the nerves that carry the signal to the brain to be interpreted.
Sounds from the external environment are first met by the pinna which directs them towards and into the external auditory meatus (or opening of the ear). Sound travels towards the tympanic membrane or eardrum, which vibrates against the ossicles. The ossicles then transmit these vibrations to the cochlea which convert the vibrations into nerve impulses which travel to the brain through the vestibulocochlear nerve.
Sounds from the external environment are first met by the pinna which directs them towards and into the external auditory meatus (or opening of the ear). Sound travels towards the tympanic membrane or eardrum, which vibrates against the ossicles. The ossicles then transmit these vibrations to the cochlea which convert the vibrations into nerve impulses which travel to the brain through the vestibulocochlear nerve.
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A patient in the clinic has a tumor at the opening of the internal acoustic meatus.
Which of the following consequences are possible?
A patient in the clinic has a tumor at the opening of the internal acoustic meatus.
Which of the following consequences are possible?
The internal auditory meatus is a canal within the petrous part of the temporal bone. The canal lies between the posterior cranial fossa and the inner ear. This canal provides passage through which the vestibulocochlear nerve, the facial nerve, and the labyrinthine artery pass from inside the skull to the inner ear and face. It also contains the vestibular ganglion. If a tumor were to grow in this area it would have a number of consequences including affecting taste (via chorda tympani of facial nerve), cause dizziness (via the vestibular ganglion), and cause dry eye (via facial nerve).
The internal auditory meatus is a canal within the petrous part of the temporal bone. The canal lies between the posterior cranial fossa and the inner ear. This canal provides passage through which the vestibulocochlear nerve, the facial nerve, and the labyrinthine artery pass from inside the skull to the inner ear and face. It also contains the vestibular ganglion. If a tumor were to grow in this area it would have a number of consequences including affecting taste (via chorda tympani of facial nerve), cause dizziness (via the vestibular ganglion), and cause dry eye (via facial nerve).
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An unsteady gait or off-balance feeling could indicate that what part of the brain is being affected?
An unsteady gait or off-balance feeling could indicate that what part of the brain is being affected?
The cerebellum, located inferoposterior to the cerebrum, is the portion of the brain that controls balance and coordinated muscle movements.
The frontal, parietal, temporal, and occipital lobes are all regions of the cerebrum. Each lobe is associated with different types of processing. The frontal lobe helps with motor integration and conscious thought. The temporal lobe is associated with memory and auditory integration. The parietal lobe is responsible for somatosensory inputs. The occipital lobe houses the visual cortex.
The cerebellum, located inferoposterior to the cerebrum, is the portion of the brain that controls balance and coordinated muscle movements.
The frontal, parietal, temporal, and occipital lobes are all regions of the cerebrum. Each lobe is associated with different types of processing. The frontal lobe helps with motor integration and conscious thought. The temporal lobe is associated with memory and auditory integration. The parietal lobe is responsible for somatosensory inputs. The occipital lobe houses the visual cortex.
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