Nerve Impulse and Transmission Quiz

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Questions and Answers

What primarily creates the resting membrane potential in a neuron?

The high concentration of chloride ions inside the neuron

The passive diffusion of sodium ions into the cell

The unequal distribution of ions across the neurolemma (correct)

The influx of calcium ions into the cell

When a neuron becomes hyperpolarized, what is the effect on its membrane potential?

The membrane potential becomes less negative than the resting potential

The membrane potential becomes more negative than the resting potential (correct)

The membrane potential remains unchanged

The membrane potential returns to zero

What is the main function of sodium-potassium pumps in neurons?

To maintain a uniform ion concentration outside the neuron

To increase intracellular calcium levels

To regulate the resting membrane potential (correct)

To generate nerve impulses directly

Which ions are primarily responsible for the polarization of a nerve cell's membrane?

Potassium (K+) and Sodium (Na+) Signup and view all the answers

What role do voltage-gated channels play in the transmission of a nerve impulse?

They open in response to changes in membrane potential Signup and view all the answers

What occurs when the membrane potential decreases from the resting state?

The cell undergoes depolarization Signup and view all the answers

What is the resting membrane potential value for a typical nerve cell?

-70 millivolts Signup and view all the answers

Which of the following best describes the term 'membrane potential'?

The electrical charge difference across a nerve cell's membrane Signup and view all the answers

What primarily contributes to the negative resting membrane potential in neurons?

More potassium leakage channels than sodium channels Signup and view all the answers

What role does the sodium potassium pump play in maintaining resting membrane potential?

It brings two K+ ions into the cell while removing three Na+ ions Signup and view all the answers

What happens to the membrane potential when an action potential is triggered?

Potassium channels open after sodium channels to repolarize the membrane Signup and view all the answers

What defines a threshold stimulus in neurons?

A stimulus capable of producing action potential in the neuron Signup and view all the answers

How long does it typically take for a neuron to return to its resting state after an action potential?

10 to 30 milliseconds Signup and view all the answers

What happens to chloride ions (Cl-) in relation to the interior of the cell?

They tend to accumulate outside of the cell due to repulsion Signup and view all the answers

During the depolarization phase of an action potential, what primarily occurs?

Sodium ions rapidly enter the cell through open sodium channels Signup and view all the answers

Which statement about ion movement in neurons is true?

More cations leave the cell than enter it Signup and view all the answers

Study Notes

Nerve Impulse

Nerve impulse is an electrical signal, relying on ion flow across a neuron's membrane.
It begins with a change in the electrical gradient across the plasma membrane.

Generation and Transmission of Nerve Impulses

All living cells have an electrical charge difference across their neurolemma, creating an electrical voltage gradient (membrane potential).
Nerve impulse is the electrochemical transmission of messages through neurons, traveling through dendrites or axons via voltage-gated ion channels in the neurolemma. These channels open and close in response to electrical voltage.
Neurolemma is polarized, with the inside negatively charged relative to the outside due to ion distribution.

Ion Distribution

Intracellular major positive ions are potassium (K+) and sodium (Na+). Extracellular major positive ions are sodium (Na+).
Potassium (K+) concentration is significantly higher inside the cell than outside (30 times).
Sodium (Na+) concentration is higher outside the cell than inside (approximately 10 times).
Sodium-potassium pumps actively transport Na+ out of the cell and K+ into the cell, maintaining these concentration gradients.
Channels in the membrane are specific to ions, allowing one type to pass while restricting others.
Negative ions inside the neurolemma include chloride (Cl-), phosphate (PO4-2), sulfate (SO4-2), and intracellular proteins.

Resting Membrane Potential (RMP)

RMP is the state of a nerve cell when not stimulated.
The resting membrane is slightly permeable to ions (more permeable to K+ than Na+).
RMP is -70 millivolts (mV).
Neurons are excitable, responding to stimuli affecting membrane potential.
Membrane hyperpolarization: membrane becomes more negative than RMP.
Membrane depolarization: membrane becomes less negative than RMP.
Sufficient depolarization triggers an action potential.
At rest, K+ ions move out of the cell due to their concentration gradient. This creates the negative inner charge.
Increased extracellular sodium (Na+) concentration, combined with the high K+ permeability of the membrane, results in the negative resting membrane potential.
The sodium-potassium pump maintains the RMP by expelling 3 Na+ ions and bringing 2 K+ ions into the cell per ATP.
Cl- tends to accumulate outside the cell, repelled by negatively charged cytoplasmic proteins.

Action Potential (AP)

Action potential is triggered by a stimulus sufficient to depolarize the membrane to threshold.
Sodium channels open rapidly, allowing Na+ influx (inside the cell), causing depolarization.
Depolarization can reach up to +50mV.
Then, sodium channels close, potassium channels open, allowing K+ efflux (out of the cell), leading to repolarization.
Repolarization restores the resting membrane potential (takes 10-30 milliseconds).
Threshold stimulus is required to produce an action potential; a weaker one will not result in a depolarization.

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Description

Test your knowledge on nerve impulses, their generation, and transmission through neurons. This quiz covers key concepts such as ion distribution, membrane potential, and the role of voltage-gated ion channels. Perfect for biology students looking to reinforce their understanding of cellular communication.