The neural system refers to the part of the body responsible for coordinating the behaviour and actions of that body and transmitting signals from one body area to another. In vertebrates, the neural or nervous system is made up of two parts: the peripheral nervous system and the central nervous system.
The central nervous system is composed of the spinal cord and the brain, while the peripheral nervous system is made up of the nerves that connect the central nervous system with all other parts of the body. The peripheral system also includes the parasympathetic and sympathetic ganglia peripheral ganglia, as well as the enteric nervous system, which functions semi-independently and controls the gastrointestinal system.
On the cellular level, what defines the neural system is the presence of neurons. These are special types of cell, also called nerve cells with unique properties that let them send signals precisely and rapidly to the other cells in the body. These signals are sent as electrochemical waves that travel through thin fibres called axioms. This causes the release of neurotransmitters at the synapses, which are junctions to the other neurons.
It is the connection between these neurons that create the neural circuits which can generate complex patterns of activities. In connection with the neurons, the neural system also has other dedicated cells that are known as glial cells. They provide metabolic and structural systems, and recent studies suggest that these cells may also play a significant role when it comes to signalling.
Neural systems are common to almost all multicellular animals, but how complex it would be may vary. Sponges and mesozoans and placozoans are the only multicellular animals without neural systems. Apart from comb jellies, hydras, corals, jellyfishes, and anemones as well as some worms and echinoderm, every animal has a nervous or neural system that includes a central cord, brain, and nerves connecting the central cord and brain. The size also varies from hundreds of cells in some worms to billions in humans.
The basic function of the neural system is to control movement and affect the environment. To achieve this, it sends signals from one cell to another in different parts of the body, and once those signals reach the cells, it activates the muscles.
These constitute a significant part of the neural system. The most fundamental thing that separates it from every other type of cell is their ability to communicate with other cells through synapsis. Many neurons usually have a protoplasmic protrusion extending to different parts of the body, making many synaptic contacts along the way. They also have axon. These axons travel in a bundle through the body. There are various types of neurons within the body, and they include sensory neurons that translate physical stimuli like sounds and light to neural signals as well as motor neurons that activate the glands and muscles.