🧠 Neuron – The Basic Unit of Nervous System

A neuron is the structural and functional unit of the neural system.

It is a microscopic, highly specialized cell designed to receive, conduct, and transmit electrical impulses.

Each neuron has three main parts:

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🔹 1. Cell Body (Soma or Cyton):

Central part of the neuron.

Contains:

Cytoplasm

Cell organelles like nucleus, mitochondria, etc.

Special granular structures called Nissl’s granules:

Made of rough endoplasmic reticulum and ribosomes.

Important for protein synthesis in neurons.

This is the metabolic centre of the neuron.

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🔹 2. Dendrites:

Short, branched projections coming out from the cell body.

Contain Nissl’s granules.

Function: Receive nerve impulses (stimuli) from other neurons or sensory receptors and carry them towards the cell body.

Think of them as antennae that pick up signals.

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🔹 3. Axon:

A long, singular fibre that arises from the cell body.

Unlike dendrites, the axon does not contain Nissl’s granules.

Its distal (far) end branches out, and each branch ends in a bulb-like structure called the synaptic knob.

➤ Synaptic Knob:

Present at the end of the axon branches.

Contains synaptic vesicles which store neurotransmitters – the chemicals that transmit signals to the next neuron or muscle cell.

➤ Function of Axon:

Conducts nerve impulses away from the cell body.

Transmits signals to:

Another neuron through a synapse (neuron-to-neuron junction),

Or to a muscle cell through a neuromuscular junction.

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✅ Summary Table:

| Part | Structure | Function |

| -------------------- | --------------------------------------------- | ----------------------------------------- |

| Cell Body (Soma) | Contains nucleus, cytoplasm, Nissl’s granules | Controls metabolism and processes signals |

| Dendrites | Short, branched, contain Nissl's granules | Carry impulses towards cell body |

| Axon | Long fibre, ends in synaptic knobs | Carries impulses away from cell body |

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📌 Key Terms:

Nissl's granules: Unique to neurons, involved in protein synthesis.

Synaptic knob: End of axon branch, releases neurotransmitters.

* Neurotransmitters: Chemicals that pass the signal to the next neuron/muscle.

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