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Nerve cell / Neuron

STRUCTURE OF NERVE CELL NEURON - Teachoo.jpg

 

  • The neuron or nerve cell is a structural and functional unit of the nervous tissue.
  • These neurons help to transmit signals to and from different parts of the body
  • These signals are in both electric and chemical forms . (We will discuss this a little later in this chapter)

 

Structure of Neuron

A neuron has three parts — the cell body , dendrites and axon .

 

 

 

Part

Details

Dendrites

Branched structure that collects information from previous neuron and passes on to the cell body .

Cell body 

It is the broad, rounded  part of the neuron that contains the nucleu s,abundant cytoplasm ( neuroplasm ) and other organelles like mitochondria, endoplasmic reticulum, Golgi body etc.

Axon

It is a long tube-like structure that carries information from the cell body to the nerve endings . Axon is covered by 1-2 sheaths called nerve fiber . A number of nerve fibers joined together to form a nerve

Nerve endings

The axon is branched terminally in muscle fibers, glands, other structures or forms synapse with the dendrites of other neurons.

Synapse

There is a gap between the nerve endings of one neuron and dendrite of the following neuron where signals are transmitted as chemical signals called neurotransmitters.

 

How exactly do these signals pass through and between neurons?

SIGNALS PASS THROUGH AND BETWEEN NEURONS - Teachoo.jpg

To sum up, 

  • Signals go from;

Dendrites → cell body → Axon → Nerve endings → Synapse → Dendrite of next neuron.

  • Signals are in the form of electric impulses as they pass from dendrites to nerve endings .
  • Signals are in the form of chemicals called neurotransmitters during transmission of messages across the synapse .

Different types of neurons

TYPES OF NEURONS - Teachoo.jpg

The different types of neurons are

1. Sensory neurons - They carry information from the receptors in the sense organs to the brain .

These are also called Afferent neurons.

Example: When we hear a sound, the signal is carried from the inner ear to the brain.

2. Motor neurons - They carry information from the brain cells to the effector organ that need to respond according to the signal sensed.

These are also called Efferent neurons.

Example: The brain cells transmit signals to the muscle cells in the hand enabling us to remove our hand from a hot surface

3. Interneurons - They carry information from the sensory neuron to motor neurons.

REFLEX ARC. - Teachoo.jpg

 

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Transcript

STRUCTURE OF NERVE CELL/ NEURON Dendrite Soma Neurotransmitters Synapse gap Nucleus Nerve ending SIGNALS PASS THROUGH AND BETWEEN NEURONS Information is collected by the dendritic tips The chemical reaction sets of electric impulse Electric impulses pass from dendrite to cell body Then passes from cell body to through the axon Reaches nerve endings at the end of axon Electric impulse sets off signals called neurotramitted across the synapse This again passes as electric signals in the next dendrite and so on TYPES OF NEURONS Sensory neurons Motor neurons Interneurons From sensory receptor cells to the brain Brain to the muscles Between different neurons in the body REFLEX ARC Stimulus Receptor Sensor Neuron Spinal Reflex ARC Response Rapid and involuntary Decision making Conscious Thought Motor Neuron Effector

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Maninder Singh

CA Maninder Singh is a Chartered Accountant for the past 12 years and a teacher from the past 16 years. He teaches Science, Economics, Accounting and English at Teachoo