Shrinithi Mahadevan

Nerve Impulse Study Guide

It is interesting to know how the nerve impulse gets transmitted through the body. It signals the action to the body through the nerve impulse.

Introduction

The nerve cells have a nucleus and other organelles. However, the nerve cells' thread lines and long extensions are unique, where the nerve impulse is transmitted. So, let's learn about the mechanism of nerve impulse.

Understanding Neurons and Nerve Impulses

  • The nervous system is composed of nerves. The nerve is a bundle of nerve cells that transmits electrical impulses.
  • The nerve impulse is the message that the neuron wants to convey. The nerve impulse travels at lightning speed because these are electrical impulses.
  • The process is similar to a light switch in a room.
  • You flip the switch, and the electricity flows quickly through the wires in the wall and reaches the light.
  • The speed is so fast that the light is switched on as soon as you flip the switch. The nerve impulse travels just as fast through the nerve network in the body.

Neuron Source

What is a Nerve Impulse?

It is interesting to know how the nervous system moves from one to the next cell. The impulse jumps as a chemical transmitter. The two cells are not connected but have a small gap. The small space between a neuron and the next cell is the synapse.

Nerve impulse Source

The nerve impulse is electric. It results from an electrical charge difference across the neurons' plasma membrane. This causes the difference in electrical charge to come about.

Nerve Impulse: Types of Potential

Types of potential Source

Resting Potential

  • When the neuron does not actively transmit a nerve impulse, it is resting. This is when it is sitting, ready to transmit the nerve impulse.
  • The sodium-potassium pump has a charge difference across the cell membrane in the resting phase.
  • The energy in ATP is used to pump the positive sodium ion out from the cell and the potassium ion into the cell.
  • This causes the inside of the neuron to become negatively charged compared to the extracellular fluid that surrounds the neuron.
  • It happens because several positively charged ions are present outside the cell compared to what is present.
  • It is this difference in the electric charge, which is called resting potential.

Action Potential

  • The nerve impulses cause a sudden reversal in the electrical charge across the resting neuron's membrane.
  • The charge reversal is called the action potential. This starts when the neuron gets a chemical signal from another cell.
  • When the signal is received, then the gate in the sodium ion channel opens up and allows the positive sodium ion to flow back into the cell. This causes the cells inside to get positively charged compared to the cells outside.
  • The charge reversal ripples down to the axon rapidly in the form of an electric current.
  • The myelin sheath is a protective layer and is wrapped around the neuron axons.
  • It causes the action potential to jump across the axon membrane from one to the other instead of spreading smoothly along the membrane.
  • This causes the speed of the impulse to increase.
  • The area where the axon terminal meets another cell is the synapse.
  • The cell and the axon terminal are separated by a synaptic cleft.
  • When the action potential reaches the axon terminal, this causes a release in the chemical molecules.
  • These molecules travel through the synaptic cleft and bind the other cell's membrane receptors.
  • If the other cell is also a neuron, this starts an action potential in the other cells.

Conclusion:

  • The brain impulse starts when a neuron gets a chemical stimulus. This is the mechanism of nerve impulse.
  • The impulse travels from the axon membrane with an electrical action potential and reaches the axon terminal.
  • The axon terminal then releases the neurotransmitters, which carry the nerve impulse to the next cell.

FAQs:

1. What happens in a nerve impulse?

Impulse is something that happens very fast. The nerve impulse causes an electrical charge across the neuron membrane. The nerve impulse is electrical because they happen when there is a difference in electric charge. A nervous impulse is called an action potential.

2. What is a nerve impulse example?

Imagine what happens when your finger touches a hot stove? You react quickly and remove your finger. This is an example of a nerve impulse.

3. Where do nerve impulses go?

The nerve impulse ends at the synapse.

4. How can nerve impulses be prevented?

If the potassium channel is opened, this does not let the action potential generate and causes the nerve impulse to stop.

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Sources:

  1. Thinking About the Nerve Impulse: The Prospects for the Development of a Comprehensive Account of Nerve Impulse Propagation. https://www.frontiersin.org/articles/10.3389/fncel.2019.00208/full. Accessed on 25 Nov, 2021.
  2. The mechanism of generation of nerve impulse and its features of propagation along the nerve fiber cells in living systems. https://medcraveonline.com/JABB/the-mechanism-of-generation-of-nerve-impulse-and-its-features-of-propagation-along-the-nerve-fiber-cells-in-living-systems.html. Accessed on 25 Nov, 2021.