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NEURON
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NEURON

THANK YOU
NERVE IMPILSE
NEUROTRANSMITTERS
CLEANING UP OF SYNAPSE
ACTION POTENTIAL
RESTING POTENTIAL
GENERATION OF MESSAGE
STRUCTURE OF NEURON
WHAT IS NEURON

Index

WHAT IS NEURON ?

NEURON

Nervous SystemA network of cells that carries information to and from the parts of the body.NEURON is one of the most important part of the nervous systemNEURON is a SPECIALIZED CELL in nervous system that receives and sends messages within the system.

structure of neuron

MYELIN SHEATH
CELL BODY
AXON
04
03
02
01
DENDRITES
SYNAPES
NODES OF RANVIER
TERMINAL BUTTONS
04
03
02
01
SCHWAN CELLS

NERVE IMPULSE

NERVE IMPULSE IS ALSO CALLED ELECTRICAL POTENTIAL

  • A nerve impulse is a gradual physicochemical change in a nerve fiber's membrane that occurs after stimulation.
  • It helps to send a signal from a receptor.
  • It also carries information along the neuron and throughout the nervous system.
  • The cell membranes of the nerve cells alter the flow of ions into the membranes, thus resulting in a charge reversal or action potential.

GENERATION OF NERVE IMPULSE

  • The cell membrane itself is semipermeable, meaning that some molecules may freely pass through the membrane while others cannot.
  • Inside and outside of the cell is a semiliquid (jelly-like) solution in which there are charged particles, or ions.
  • Although both positive and negative ions are located inside and outside of the cell
  • The Relative charge of ions inside the cell is mostly negative .
  • The Relative charge of ions outside the cell is mostly positive .
  • Due to DIFFUSION ( the process of ions moving from areas of high concentration to areas of low concentration )
A NEURON that's at rest - not currently firing a neural impulse or message - is actually electrically charged.

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RESTING POTENTIAL

  • Some molecules that are outside the cell enter through tiny protein openings, or channels, in the membrane, while molecules inside the cell can pass through the same channels to the outside of the cell.
  • Many of these channels are gated—they open or close based on the electrical potential of the membrane.
  • The outside of the cell are positive ( SODIUM IONS) and the inside of the cell are Negative .
  • The opposite electrical charges attract each other , This difference in charges creates an electrical potential .
  • But when the cell receives a strong enough stimulation from another cell (at the dendrites or soma), the cell membrane opens up those particular channels, one after the other, all down its surface, allowing the sodium ions to rush into the cell.
  • That causes the inside of the cell to become mostly positive and the outside of the cell to become mostly negative, because many of the positive sodium ions are now inside the cell.

ACTION POTENTIAL

When the electrical charge reversal will take place due to electrostatic pressure , the cell will come in ACTION POTENTIAL( FIRING )
  • The cell come into action potential when the cell receives a strong enough stimulation from another cell (at the dendrites or soma)
  • There are 2 particular channels which only opens up for particular ions.
  • The cell membrane opens up those particular channels, one after the other, all down its surface, allowing the sodium ions to rush into the cell.
  • Due to which inside the cell will becomes relatively more positively cherged where as outside of the cell will become relatively more negatively charged
  • After the impulse is passed the return to its resting state.
  • First, the sodium ion channels close immediately after theaction potential has passed, allowing no more sodium ions to enter.
  • There are PUMPS present on the cell membrane which literally pumps the sodium ions outside the cell ( this process is slow)
  • Small, positively charged potassium ions inside the neuron move rapidly out of the cell after the action potential passes
  • Helping quick restration of negative charge inside of the cell.
  • Now the cell becomes negative inside and positive outside and the neuron is capable of “firing off” another message.
BACK TO RESTING POTENTIAL

Neurotransmitters

- Neurotransmitters are the chemical messengers of our body. They carry messages from one nerve cell across to the next nerve, muscle or gland cell. - They're located in a part of the neuron called axon terminal and are stored in thin-wall sacs called synaptic vesicles. - As a message ravels along nerve cell, the neurotransmitters carry the message are then released from the axon terminal into a fluid-filled space called as synapse.- These neurotransmitters can either turns cell on (called an excitatory effect) or turns cell off (called as inhibitory effect).

Cleaning up of Synapse

•The neurotransmitter have to get out of the receptor sites before the next stimulation occur .• Some just drift away through the process of diffusion , but most will end up back in the presynaptic neuron to be repackaged into the synaptic vesicles is called reuptake.•There is one neurotransmitter that is not taken back into the vesicles because of ACH , responsible for muscle activity and this needs to happen rapidly.• It is not possible to wait around for the "sucking up process ".•Instead an enzyme specifically designed to break apart ACH, clears the synaptic gap very quickly this process is called enzyme degradation.

PRESENTED BY

  1. AMANPREET KAUR (2413)
  2. ANITA KUMARI (2415)
  3. ANJALI (2419)
  4. ARSHMEET KAUR (2438)
  5. BHAVLEEN KAUR (2446) (TEAM HEAD )

Thanks!

AXON

  • Axon is a fiber ( or tube like structure) that is attached to the soma.
  • It carries electrical impulse from the cell body to the axon terminals

GLIAL CELLS

  • Glial calls are one of the primary cells which are known as the partners of Neuron
  • Two types of glial cells are : SCHWAN CELL and OLIGODENDROCITES
  • They provide support for the Neuron to grow, provide nutrients to the cell, produce Myelin coats, Clean up the waste products (DEAD NEURONS) and generation of new cells.

SCHWAN CELL

  • Schwann cells generate a layer of fatty substances called myelin sheath
  • It is a type of glial cells

AXON TERMINALS

  • The end of the axon branches out into several shorter fibers that have swellings or little knobs on the ends called Axon terminals
  • These are responsible for communicating with other nerve cells.
  • Other names of Axon Terminals are :
  • presynaptic terminals
  • terminal buttons
  • synaptic knobs
  • The neuron constantly adds together the effects of the “fire” messages and subtracts the “don’t fire” messages, and if the fire messages are great enough, the threshold is crossed and the neuron fires.
  • When a neuron does fire, it fires in an all-or-none fashion.
  • There’s no such thing as “partial” firing of a neuron.

DENDRITES

  • Present in the begining of the neuron
  • These are branch-like structures that receive messages from other neurons
  • Allows the transmission of messages to the cell body.

https://www.britannica.com/video/73074/movement-impulses-nerve-cell-changes

*NOTEBundles of myelin-coated axons travel together as “cables” in the central nervous system called tractsIn the peripheral nervous system bundles of axons are called nerves.

MYELIN SHEATH

  • Myelin sheath is layers fatty substance
  • It is wrapped around the shaft of the Axon.
  • Its creates a protective and insulating sheath
  • It also speeds up the neural message traveling down the axon

CELL BODY

* NUCLEUS : A neuron is an oval shaped membrane-bound structure found in the soma or body of the neuron.
  • Cell body is also known as ' SOMA '
  • Soma is the part of the cell ( neuron) that contains the nucleus
  • keeps the entire cell alive and functioning.

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