Types of Neurons on the Basis of Structure: Įach neuron has several branched processes (projections). They are commonly found in autonomous and somatic neural systems. In non-myelinated nerve fibres Schwann cells do not form myelin sheath and are without nodes of Ranvier. Myelinated nerve fibres are found in cranial and spinal nerves. The gaps between two adjacent myelin sheaths are called nodes of Ranvier. In myelinated nerve fibres Schwann cells form myelin sheath around the axon. There are two types of axon namely myelinated and non-myelinated. The axon conducts nerve impulses away from the cell body, therefore, called an efferent process. When terminal arborizations of the axon meet the dendrites of another neuron to form a synapse they form synaptic knobs (= end plates). The axon ends in a group of branches, the terminal arborizations (= axon terminals or telodendria). The axon contains neurofibrils and neurotubules but does not have Nissl’s granules, Golgi complex, ribosomes, pigment granules, fat globules, etc. Most sensitive part of neuron is axon hillock. The part of cyton from where the axon arises is called axon hillock. They conduct nerve impulse towards the cell body and are called afferent processes (= receiving processes).Īxon is a single, usually very long process of uniform thickness. The dendrites contain neurofibrils, neurotubules and Nissl’s granules. These are usually shorter, tapering and much branched processes. These are of two types: dendrites or dendrons and an axon or axis cylinder or neuraxon. The processes of neurons are called neurites. The cell body is the region of Neuron in which an electrical impulse is generated. Neurotubules are in fact, microtubules which maintain the shape of the neuron. Neurofibrils play a role in the transmission of impulses. Presence of neurofibrils and Nissl’s granules is characteristic to all neurons. The cytoplasm has mitochondria, Golgi apparatus, rough endoplasmic reticulum, ribosomes, lysosomes, fat globules, pigment granules, neurofibrils, neurotubules and Nissl’s granules. It has abundant cytoplasm, called neuroplasm and a relatively large spherical central nucleus with a distinct nucleolus. Like a typical cell it consists of cytoplasm, nucleus and cell membrane. It may be up to 13.5 µm in diameter and may be irregular, spherical, oval, rounded, star-shaped or pyramidal. Neuron comprise a cell body (soma),dendrites ,and an axon that ends at a terminal. Neuron is a structural and functional unit of the nervous system.Human neural system has about 100 billion neurons.