Neural Action Potential and Propagation Quiz

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Questions and Answers

What is the resting membrane potential typically for a neuron?

-20 mV

-40 mV

-90 mV

-60 mV (correct)

What is the main role of K+ in generating membrane potential?

Stabilizing the resting membrane potential

Increasing the permeability of the membrane to Na+ ions

Balancing the (+) charges of intracellular cations (correct)

Balancing the (-) charges of intracellular anions

What is the function of the ATP-driven sodium-potassium pump?

Generating membrane potential

Increasing the permeability of the membrane to Cl- ions

Maintaining the concentration gradients of Na+ and K+ (correct)

Ejecting three K+ from the cell

What contributes to the cell being more negative inside?

K+ flowing out of the cell Signup and view all the answers

What is the main reason for the separation of (+) and (-) charges across the membrane?

Small buildup of (-) ions in cytosol along the inside of the membrane Signup and view all the answers

What is the electrical property of neurons and synapse structure?

Highly irritable or electrically excitable Signup and view all the answers

What is the role of the leakage ion channels in the membrane?

Enabling the diffusion of various ions at rest Signup and view all the answers

What is the unit of measurement for potential energy in the context of the resting membrane potential?

Millivolts Signup and view all the answers

What neurotransmitter is involved in reward, motivation, and motor control?

Dopamine Signup and view all the answers

Which neurotransmitter is mainly inhibitory and produces a calming effect?

GABA Signup and view all the answers

What neurotransmitter is linked to pain control and pleasure?

Endorphins Signup and view all the answers

Which neurotransmitter is involved in controlling alertness and arousal?

Norepinephrine Signup and view all the answers

What neurotransmitter affects hunger, sleep, arousal, and mood?

Serotonin Signup and view all the answers

Which neurotransmitter activates the sympathetic nervous system by increasing heart rate and enlarging pupils?

Epinephrine Signup and view all the answers

What neurotransmitter is a major excitatory neurotransmitter involved in information transmission throughout the brain?

Glutamate Signup and view all the answers

Which neurotransmitter is released in excess during allergic reactions, causing swelling and inflammation of tissues?

Histamine Signup and view all the answers

Which cranial nerve controls most facial expressions and secretion of tears and saliva?

Facial Signup and view all the answers

Which cranial nerve is responsible for innervating the superior oblique muscle of the eye?

Trochlear Signup and view all the answers

Which cranial nerve is associated with the sense of smell?

Olfactory Signup and view all the answers

Which cranial nerve is responsible for controlling the trapezius and sternocleidomastoid muscles, as well as swallowing movements?

Accessory Signup and view all the answers

What is the result of excessive K+ efflux following action potential (AP)?

After-hyperpolarization (undershoot) Signup and view all the answers

What is the threshold for action potential (AP)?

Depolarization reaches -55 to -50 mV Signup and view all the answers

How is stimulus intensity coded?

By frequency of action potentials Signup and view all the answers

What is the function of absolute refractory period?

Enforces one-way transmission Signup and view all the answers

What is the effect of myelin sheath on the rate of action potential (AP) propagation?

Dramatically increases Signup and view all the answers

What is the role of the relative refractory period?

Axon’s threshold for AP generation is substantially elevated Signup and view all the answers

How do nerve fibers transmit impulses where speed is essential?

More rapidly (100 m/s or more) Signup and view all the answers

What is the role of all-or-none phenomenon in action potential (AP)?

AP either happens completely or not at all Signup and view all the answers

What is the range of impulse transmission speed in nerve fibers?

100 m/s or more Signup and view all the answers

What is the function of the after-hyperpolarization (undershoot)?

Results from excessive K+ efflux following action potential (AP) Signup and view all the answers

What is the effect of axon diameter on the rate of impulse propagation?

Affects the rate of impulse propagation Signup and view all the answers

What is the role of salutatory conduction?

Occurs on myelinated axons Signup and view all the answers

What is the main characteristic of graded potentials?

They are short-lived, localized changes in membrane potential caused by stimuli Signup and view all the answers

What triggers the opening of gated ion channels in response to graded potentials?

Strength of the stimulus Signup and view all the answers

What occurs when neurotransmitters released by another neuron influence a neuron beyond the synapse?

Postsynaptic potentials Signup and view all the answers

What is the process by which graded potentials add together, resulting in larger depolarizing or hyperpolarizing potentials?

Summation Signup and view all the answers

What is the main event in synapse structure involving the arrival of an action potential at the axon terminal?

Release of neurotransmitters Signup and view all the answers

What is the total amplitude of action potentials?

Around 100 mV Signup and view all the answers

Where do neurons and muscle cells typically generate action potentials?

In axons Signup and view all the answers

What is the state of gated Na+ and K+ channels during the resting state of a neuron?

Closed Signup and view all the answers

What characterizes the depolarizing phase of an action potential?

Opening of voltage-gated Na+ channels Signup and view all the answers

What characterizes the repolarizing phase of an action potential?

Inactivation of Na+ channels and the opening of K+ channels Signup and view all the answers

What occurs during hyperpolarization following an action potential?

Some K+ channels remain open, and Na+ channels reset Signup and view all the answers

What is the critical mechanism for transmitting signals over long distances in neurons?

Action potential Signup and view all the answers

Study Notes

Neural Action Potential and Propagation

After-hyperpolarization (undershoot) results from excessive K+ efflux following action potential (AP)
AP must be propagated along axon’s entire length for neuron signaling
AP self-propagates at constant velocity on unmyelinated axons (salutatory conduction on myelinated axons)
Threshold for AP is when depolarization reaches -55 to -50 mV
All-or-none phenomenon: AP either happens completely or not at all
Stimulus intensity is coded by frequency of AP, not by amplitude of individual APs
Absolute refractory period: from opening of Na+ channels until reset, enforces one-way transmission
Relative refractory period: following absolute refractory period, axon’s threshold for AP generation is substantially elevated
Nerve fibers transmit impulses more rapidly (100 m/s or more) where speed is essential
Axon diameter and myelination affect rate of impulse propagation
Myelin sheath dramatically increases rate of AP propagation
Electrical signals rely on four types of ion channels: leakage, ligand-gated, mechanically gated, and voltage-gated

Neurophysiology: Graded Potentials, Synapse Structure, and Action Potentials

Graded potentials are short-lived, localized changes in membrane potential caused by stimuli, resulting in depolarization or hyperpolarization.
Graded potentials vary in magnitude with the strength of the stimulus and trigger gated ion channels to open.
Postsynaptic potentials occur when neurotransmitters released by another neuron influence a neuron beyond the synapse.
Summation is the process by which graded potentials add together, resulting in larger depolarizing or hyperpolarizing potentials.
Synapse structure involves the arrival of an action potential at the axon terminal, followed by the release of neurotransmitters and their effects on the postsynaptic membrane.
Action potentials are brief reversals of membrane potential with a total amplitude of around 100 mV and do not decrease in strength with distance.
Neurons and muscle cells can generate action potentials, typically in axons, and involve depolarization, repolarization, and often hyperpolarization.
The resting state of a neuron involves closed gated Na+ and K+ channels, with leakage channels open.
The depolarizing phase of an action potential involves the opening of voltage-gated Na+ channels, allowing Na+ to rush into the cell and depolarize the membrane.
The repolarizing phase of an action potential involves the inactivation of Na+ channels and the opening of K+ channels, allowing K+ to rush out of the cell and contribute to repolarization.
Hyperpolarization occurs as some K+ channels remain open, and Na+ channels reset, temporarily making the membrane potential more negative than the resting level.
The action potential is a critical mechanism for transmitting signals over long distances and involves the opening and closing of voltage-gated channels in response to changes in membrane potential.

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Description

Test your knowledge of neural action potential and propagation with this quiz. Explore topics such as after-hyperpolarization, AP propagation, threshold for AP, refractory periods, myelination, and ion channels. Also, dive into graded potentials, synapse structure, neurotransmitters, summation, and the phases of action potentials.