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Questions and Answers

What is the membrane potential reached during the peak of an action potential?

-90 mV

-70 mV

+30 mV (correct)

0 mV

What primarily causes the rapid influx of Na+ during an action potential?

Na+ channel activation

Working of the Na+/K+ pump

High Na+ permeability of the membrane

Large Na+ concentration gradient and electrical gradient (correct)

What happens to the membrane potential after K+ channels open at +30 mV?

It returns to resting potential of -70 mV

It decreases to -90 mV (correct)

It increases to +60 mV

It remains at +30 mV

During the action potential, when do Na+ channels close?

At the peak of the action potential Signup and view all the answers

What role does the Na+/K+ pump play in the action potential process?

It resets the resting membrane potential Signup and view all the answers

What initiates the opening of the voltage-gated Ca2+ channel?

Rapid influx of Na+ Signup and view all the answers

Which of the following accurately describes the relationship between stimulus size and neurotransmitter release?

Large stimuli result in large NT release Signup and view all the answers

What happens if the threshold of -55 mV is not reached at the axon hillock?

Nothing happens Signup and view all the answers

What role does Ca2+ play once it enters the cell?

It causes fusion of neurotransmitter vesicles Signup and view all the answers

What type of receptors bind neurotransmitters on the post-synaptic cell?

Ligand-gated Na+ channels Signup and view all the answers

How does the influx of Na+ affect the membrane potential?

It raises the membrane potential to threshold Signup and view all the answers

What occurs immediately following the arrival of an action potential at a nerve terminal?

Release of neurotransmitters into the synapse Signup and view all the answers

What is the role of graded potentials in sensory cells?

They result in a graded release of neurotransmitters Signup and view all the answers

What effect does achieving the threshold of -55 mV have on action potentials?

It generates a low frequency of action potentials Signup and view all the answers

What does the rapid influx of Ca2+ cause inside the cell?

Diffusion across the entire cell Signup and view all the answers

What is the primary function of sensory cell types in sensory systems?

To release neurotransmitters when activated Signup and view all the answers

How do graded potentials in sensory cells affect membrane potential?

They increase in response to enhanced stimuli. Signup and view all the answers

What is the main method by which neurotransmitters travel from pre-synaptic to post-synaptic cells?

Diffusion across the synaptic gap Signup and view all the answers

What speed can action potentials travel in axons?

Up to 100 metres/second Signup and view all the answers

Which of the following is NOT a role of ion channels in nerve impulse transmission?

Transferring information across long distances instantly Signup and view all the answers

What occurs in the cell body of a nerve cell in relation to sensory input?

It acts as a sensory cell gathering information from dendrites. Signup and view all the answers

What role do muscle stretch receptors serve in the nervous system?

They detect changes in muscle length. Signup and view all the answers

Which statement accurately describes the flow of information in a synapse?

Information transfer in synapses is very quick, facilitated by neurotransmitters. Signup and view all the answers

What is the primary consequence of ligand binding to the ligand-gated Na+ channel?

Rapid Na+ influx into the cell Signup and view all the answers

What is generated as a result of the rapid Na+ influx into sensory cells?

Graded potential Signup and view all the answers

Which ion's movement primarily affects the membrane potential when the ligand-gated channel opens?

Na+ Signup and view all the answers

What does an increase in membrane potential indicate after Na+ rushes into the cell?

Depolarization of the cell Signup and view all the answers

In what phase of activation do gated Na+ channels get stimulated?

Activation phase Signup and view all the answers

What role does the ligand play in the function of the ligand-gated Na+ channel?

It causes a conformational change opening the channel Signup and view all the answers

What type of potential is primarily associated with the activation of gated Na+ channels?

Graded potential Signup and view all the answers

Which of the following correctly describes the condition inside the cell before Na+ influx?

Negative membrane potential Signup and view all the answers

What happens to the intracellular Ca2+ levels during the activation of gated Na+ channels?

They remain unchanged. Signup and view all the answers

When the ligand-gated Na+ channels open, how does this affect the overall ionic gradients?

Disrupts Na+ concentration gradient Signup and view all the answers

How does the resting membrane potential of a neuron typically behave?

It maintains a steady level of about -70mV. Signup and view all the answers

What characterizes the medium frequency of action potentials based on the given content?

It reflects optimal neurotransmitter release. Signup and view all the answers

Which of the following best describes action potentials?

Small, identical electrical changes in individual parts of a neuron. Signup and view all the answers

What is the effect of low-frequency action potentials on neurotransmitter action?

They lead to insufficient neurotransmitter release. Signup and view all the answers

What is one role of neuroglia in relation to action potentials?

They facilitate action potential propagation in one direction. Signup and view all the answers

Which statement about synaptic transmission is true according to the content?

It can work by diffusion of neurotransmitters. Signup and view all the answers

What is the consequence of high-frequency action potentials in the context of neurotransmitter action?

They enhance neurotransmitter efficacy to an excessive level. Signup and view all the answers

In terms of graded potentials, what is their primary role in the nerve cell body?

To integrate synaptic input and influence cell excitability. Signup and view all the answers

What does the time taken for ion diffusion to achieve equilibrium indicate about nerve cells?

Nerve impulses may rely on diffusion for rapid signaling. Signup and view all the answers

Why is the propagation of action potentials in one direction important?

It ensures the effective transmission of signals to target neurons. Signup and view all the answers

Study Notes

Nervous System

Sensory cells convert a stimulus into a neurotransmitter release
The nervous system has three types of neurons: Sensory, Inter, and Motor neurons.
Sensory cells generate graded potentials, which are small changes in membrane potential that only travel short distances.
Sensory cells release neurotransmitters when activated.

Nerve Impulse Transmission

In nerve impulse transmission, the role of ion channels is crucial. They facilitate rapid changes in membrane potential, allowing for quick information transfer.
Graded potentials are generated in the cell body of nerve cells.
Axons are responsible for transmitting nerve impulses over long distances, traveling at speeds up to 100 meters per second.
Synapses are specialized junctions where nerve impulses are transmitted from one neuron to another. They allow for extremely quick information transfer, involving the release and diffusion of neurotransmitters.
Neurotransmitters (NTs) are released from the presynaptic cell and bind to receptors on the postsynaptic cell, causing a change in membrane potential.

Action Potentials

Action potentials are short, identical electrical changes that occur in individual parts of a neuron.
The frequency of action potentials is determined by the intensity of the stimulus.
Action potentials propagate rapidly along the axon due to the opening and closing of voltage-gated sodium (Na+) and potassium (K+) channels.
The opening of voltage-gated Na+ channels causes a rapid influx of Na+ ions into the cell, leading to depolarization (a more positive membrane potential).
As the membrane potential rises, voltage-gated K+ channels open, allowing K+ ions to flow out of the cell, leading to repolarization.
The membrane potential then returns to its resting state, and the cycle repeats.

Nervous System: Overview

The nervous system plays a crucial role in decision-making and controlling various bodily functions, including muscle function, the gastrointestinal tract (GIT), and other processes.
The nervous system senses both external and internal environments.

Diffusion

Diffusion is the movement of molecules from an area of high concentration to an area of low concentration.
Diffusion times for ions to reach 99% equilibrium can vary significantly based on distance, with longer distances requiring much longer times. With this in mind, the nervous system is unable to rely solely on diffusion for long-distance signaling.### Action Potential
Sodium ions (Na+) influx into the cell is rapid because the sodium gradient is large as well as the electrical gradient.
Sodium channels close when the membrane potential reaches +30 mV
Potassium channels open at +30 mV
Potassium ions (K+) efflux out of the cell is rapid due to the potassium gradient and the electrical gradient
The sodium-potassium pump resets the resting membrane potential to -70mV

Nerve Cells

The action potential originates from the initial segment of the axon and propagates down the axon towards the terminals
Action potentials propagate in one direction because of the refractory period
Insulated axons allow action potentials to propagate faster than un-insulated axons
Myelin sheaths are formed by neuroglia cells
Specialized sensory cells respond to specific stimuli which are converted into action potentials.

Synaptic Transmission

Synapses are junctions between neurons which allow communication using neurotransmitters
Synapses regulate neuronal circuits

Local Anaesthetics & Neurotoxins

Local anaesthetics block sodium channels and prevent the conduction of action potentials.
Neurotoxins interfere with synaptic transmission, preventing neurotransmitter release or binding.

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Untitled Quiz

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Questions and Answers

What is the membrane potential reached during the peak of an action potential?

What primarily causes the rapid influx of Na+ during an action potential?

What happens to the membrane potential after K+ channels open at +30 mV?

During the action potential, when do Na+ channels close?

What role does the Na+/K+ pump play in the action potential process?

What initiates the opening of the voltage-gated Ca2+ channel?

Which of the following accurately describes the relationship between stimulus size and neurotransmitter release?

What happens if the threshold of -55 mV is not reached at the axon hillock?

What role does Ca2+ play once it enters the cell?

What type of receptors bind neurotransmitters on the post-synaptic cell?

How does the influx of Na+ affect the membrane potential?

What occurs immediately following the arrival of an action potential at a nerve terminal?

What is the role of graded potentials in sensory cells?

What effect does achieving the threshold of -55 mV have on action potentials?

What does the rapid influx of Ca2+ cause inside the cell?

What is the primary function of sensory cell types in sensory systems?

How do graded potentials in sensory cells affect membrane potential?

What is the main method by which neurotransmitters travel from pre-synaptic to post-synaptic cells?

What speed can action potentials travel in axons?

Which of the following is NOT a role of ion channels in nerve impulse transmission?

What occurs in the cell body of a nerve cell in relation to sensory input?

What role do muscle stretch receptors serve in the nervous system?

Which statement accurately describes the flow of information in a synapse?

What is the primary consequence of ligand binding to the ligand-gated Na+ channel?

What is generated as a result of the rapid Na+ influx into sensory cells?

Which ion's movement primarily affects the membrane potential when the ligand-gated channel opens?

What does an increase in membrane potential indicate after Na+ rushes into the cell?

In what phase of activation do gated Na+ channels get stimulated?

What role does the ligand play in the function of the ligand-gated Na+ channel?

What type of potential is primarily associated with the activation of gated Na+ channels?

Which of the following correctly describes the condition inside the cell before Na+ influx?

What happens to the intracellular Ca2+ levels during the activation of gated Na+ channels?

When the ligand-gated Na+ channels open, how does this affect the overall ionic gradients?

How does the resting membrane potential of a neuron typically behave?

What characterizes the medium frequency of action potentials based on the given content?

Which of the following best describes action potentials?

What is the effect of low-frequency action potentials on neurotransmitter action?

What is one role of neuroglia in relation to action potentials?

Which statement about synaptic transmission is true according to the content?

What is the consequence of high-frequency action potentials in the context of neurotransmitter action?

In terms of graded potentials, what is their primary role in the nerve cell body?

What does the time taken for ion diffusion to achieve equilibrium indicate about nerve cells?

Why is the propagation of action potentials in one direction important?

Study Notes

Nervous System

Nerve Impulse Transmission

Action Potentials

Nervous System: Overview

Diffusion

Nerve Cells

Synaptic Transmission

Local Anaesthetics & Neurotoxins

Studying That Suits You

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