Nerve Cell or Neuron

Nerve cell or neuron is the unit of the nervous system The human nervous system consists of billions of neurons plus supporting (neuroglial) cells. Neurons are specialized cells that are able to conduct nerve impulses from receptors to coordinators and from coordinators to effectors. In this way they communicate with each other and with other types of body cells.
The nucleus and most of the cytoplasm of a neuron is located in it cell body. Different processes extend out from cell body. These are called dendrites and axons. Dendrites conduct impulses toward cell body and axons conduct impulses away from cell body.
Schwann cells are special neurological cells located at regular intervals along axons. In some neurons, Schwann cells secrete a fatty layer called myelin sheath, over axons. Between the areas of myelin on
An axon, there are non-myelinated points, called the nodes of Ranvier. Myelin sheath is an insulator so the membrane coated with this sheath does not conduct nerve impulse. In such a neuron, impulses ‘jump’ over the areas of myelin going from node to node. Such impulses are called salutatory (‘jumping’) impulses. This increases the speed of nerve impulses.
On the basis of their functions, neurons are three types;
1- Sensory neurons: conduct sensory information (nerve impulse) from receptors towards the CNS. Sensory neurons have one dendrite and one axon.
2- Interneurons: from brain and spinal cord. They receive information , interpret them and stimulate motor neurons. They have many dendrites and axons.