The nervous system is made up of two main types of cells that work closely together:
- Neurons (nerve cells)
- Glial cells (supporting cells or neuroglia)
Together, these cells allow the nervous system to communicate, process information, and keep the brain, spinal cord, and nerves functioning properly.
Neurons
Neurons are the basic building blocks of the nervous system. Their main job is to receive, process, and transmit information throughout the body using electrical and chemical signals.
Neurons allow us to:
- Think
- Learn
- Remember
- Feel emotions
- Move our muscles
- Sense our surroundings
- Communicate with other parts of the body
There are billions of neurons working together in the human brain and nervous system.
Glial Cells (Neuroglia)
Glial cells, also called neuroglia, are the support cells of the nervous system.
Although they do not carry nerve impulses like neurons, they are essential for keeping neurons healthy and working efficiently.
Glial cells provide:
- Physical support for neurons.
- Protection for nerve cells.
- Nutrients and oxygen to neurons.
- Removal of waste products.
- Repair of damaged nervous tissue.
- Formation of the myelin sheath around many nerve fibres.
- Maintenance of the chemical environment needed for nerve communication.
There are more glial cells than neurons in many parts of the nervous system.
How Neurons and Glial Cells Work Together
Neurons and glial cells depend on each other.
- Neurons send and receive information.
- Glial cells support, protect, nourish, and maintain neurons.
Without glial cells, neurons would not survive or function properly.
Parts of a Neuron
A neuron has several important parts.
1. Dendrites
Dendrites are branch-like extensions attached to the cell body.
Their job is to:
- Receive signals from other neurons.
- Carry incoming information toward the cell body (soma).
Think of dendrites as the neuron's receiving branches.
2. Cell Body (Soma)
The cell body, also called the soma, is the control centre of the neuron.
It contains:
- The nucleus
- DNA
- Organelles that keep the neuron alive
The soma processes information received from the dendrites before passing it to the axon.
3. Axon
The axon is a long, slender fibre that extends from the cell body.
Its job is to:
- Carry electrical impulses away from the soma.
- Send signals to other neurons, muscles, or glands.
Some axons are only a few millimetres long, while others can extend over one metre in length.
4. Myelin Sheath
The myelin sheath is a fatty, insulating layer that surrounds many axons.
Myelin is produced by specialized glial cells:
- Oligodendrocytes in the Central Nervous System (brain and spinal cord).
- Schwann cells in the Peripheral Nervous System.
The myelin sheath helps to:
- Protect nerve fibres.
- Speed up the transmission of nerve impulses.
- Improve communication between neurons.
- Reduce the loss of electrical signals.
Damage to the myelin sheath can slow or interrupt communication between the brain and the rest of the body.
5. Axon Terminals
At the end of the axon are axon terminals.
These terminals release chemical messengers called neurotransmitters, which pass information to the next neuron, muscle, or gland.
How a Nerve Signal Travels
A nerve message follows this pathway:
Dendrites → Cell Body (Soma) → Axon → Axon Terminals → Next Neuron, Muscle, or Gland
This process happens extremely quickly, allowing the nervous system to respond almost instantly.
Neurons vs. Glial Cells
| Feature | Neurons | Glial Cells |
|---|---|---|
| Main role | Carry nerve signals | Support and protect neurons |
| Send electrical impulses | Yes | No |
| Receive information | Yes | No |
| Provide nutrients | No | Yes |
| Form myelin | No | Yes |
| Remove waste | No | Yes |
| Help repair damage | Limited | Yes |
Why Myelin Is Important
The myelin sheath acts like the insulation around an electrical wire.
Without myelin:
- Nerve signals travel more slowly.
- Communication between the brain and body becomes less efficient.
- Movement, sensation, and coordination may be affected.
Healthy myelin allows nerve impulses to travel rapidly and accurately throughout the nervous system.
Summary
The nervous system depends on two main types of cells: neurons and glial cells. Neurons are responsible for receiving, processing, and transmitting information, while glial cells support, protect, and nourish neurons so they can function properly.
Each neuron has several important parts. Dendrites receive incoming signals, the cell body (soma) processes the information, the axon carries signals away from the soma, and the axon terminals pass messages to the next cell. Many axons are covered by a myelin sheath, a protective insulating layer formed by glial cells that helps nerve impulses travel quickly and efficiently.
Together, neurons and glial cells form the foundation of the nervous system, enabling the brain, spinal cord, and nerves to communicate with every part of the body.
Key Points
- The nervous system is made up of neurons and glial cells.
- Neurons are the basic building blocks that transmit electrical and chemical signals.
- Glial cells support, protect, nourish, and repair neurons.
- Dendrites receive signals from other neurons.
- The cell body (soma) contains the nucleus and processes incoming information.
- The axon carries signals away from the soma.
- The myelin sheath is a protective insulating layer around many axons that speeds up nerve impulse transmission.
- Healthy communication between neurons and glial cells is essential for thinking, movement, sensation, learning, memory, and the normal functioning of the entire nervous system.
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