The cells of nervous tissue are highly specialized in processing information.
Neurons transmit nerve impulses and glial cells act together with them.
Function
The function of nervous tissue is to provide communication between the body’s organs and the external environment.
Everything happens very quickly. Through neurons, the nervous system receives stimuli, decodes messages and develops responses.
For example: cold (external stimulus) is received by skin receptors, transmitted by sensory neurons and interpreted in the central nervous system.
Nerve Cells
Nervous tissue cells can be of two types: neurons and glial cells.
Representation of a neuron and glial cells. Note the oligodendrocyte that surrounds the neuronal axon.
Neurons
Neurons transmit information through chemical mediators, neurotransmitters , and electrical impulses.
We can identify three regions in most neurons, they are:
- Cell body : the nucleus and organelles, for example, mitochondria, are located in it.
- Axon: is a long extension of the cell body, usually single, of constant thickness. It is surrounded by macroglia of two types: Oligodendrocytes and Schwann cells.
- Dendrites: are short extensions of the cell body, with many branches that taper at the tips.
They can be of several types and classified as follows:
- According to the shape : Multipolar, Bipolar and Unipolar Neurons
- According to function : Sensory, Motor and Integrative Neurons
Glial cells
Glial cells, or neuroglia , are much more numerous than neurons. Their function is to nourish and protect the nervous system.
Furthermore, they help regulate synapses and transmit electrical impulses.
There are two types of glial cells, namely:
- Microglia: protect the nervous system, acting in a similar way to macrophages .
- Macroglia : there are four subtypes, each with a specific function, helping in the transmission of nerve impulses. They are: astrocytes, oligodendrocytes, ependymocytes and Schwann cells.
Features
Nervous tissue constitutes the organs of the nervous system , which can be classified into two:
Central Nervous System (CNS)
Formed by the brain , which is inside the cranial cavity, and the spinal cord.
In the brain and cerebellum, which make up the encephalon, the cell bodies of neurons are concentrated in the outermost region (cortex) forming the gray matter .
The extensions (axons) form the innermost region called white matter .
While in the spinal cord , the white matter is more external and the gray matter is internal.
Learn more: Central Nervous System .
Peripheral Nervous System
Formed by nerves and ganglia. Nerves are composed of nerve fibers.
The fibers, in turn, are made up of axons and Schwann cells, which cover them.
Ganglia are dilated portions of nerves, where neuron cell bodies are concentrated.
Learn more: Peripheral Nervous System .
Nerve Impulses and Synapses
The transmission of nerve impulses is the way neurons communicate. Impulses are phenomena of an electrochemical nature, since they involve chemical substances and the propagation of electrical signals.
Synapses occur between the extensions of neurons (the axon of one cell and the dendrites of the neighboring cell). They occur due to chemical substances, mediators called neurotransmitters .
Electrical signals generate an action potential in the neuron membranes, which means there is a change in electrical charges.
