Nervous Tissue

 

Nervous tissue is mainly made up of two types of nerve cells neurons and neuroglia. Neurons are highly specialised cells that conduct impulses throughout the central and peripheral nervous system.

 

There are three basic types of neurons:

 

1. Sensory neurons that transmit sensory information e.g. touch, pressure, temperature from receptors in the body to the central nervous system (spinal cord and brain)

2. Motor neurons that transmit messages from the central nervous system to the muscles and glands

3. Interneurons that relay information between the sensory and motor neurons

 

Neuroglia

Neuroglia, or glial cells, act as a support system for the neurons of the nervous system. Each neuron in the body is surrounded by anywhere from 6 to 60 neuroglia. The function of the neuroglia is to protect, provide nutrition, and insulate the neuron.

 

 

 

 

 

 

 

 

 

 

1. Cell body (soma)

The cell body contains a nucleus, cytoplasm and other typical organelles e.g. mitochondria, ribosomes, Golgi apparatus etc. It has a number of processes, which vary depending on the type of nerve cell, which is called dendrites.

 

2. Dendrites

The dendrite is a receptor site and its function is to conduct impulses towards the cell body.

 

3. Axon

The axon is usually a single long, thin process, that conducts impulses to the effector site e.g. muscle, or a connecting neuron where it can release neurotransmitter chemicals at its terminal points.

 

4. Myelin sheath

Myelin is produced by Schwann cells in the peripheral nervous system and oligodendrocytes in the central nervous system. They produce myelin which forms a sheath around the axon. Myelin insulates the nerve fibre and speeds up the rate of impulse conduction.