Answer
The neuron is the basic functional cell of nervous tissue. Its gross anatomical form comprises the following parts: a group of small protoplasmic processes (dendrites) at one end ; a spheroidal or irregularly shaped cell body ; a single long thread-like or rope-like process (axon) at the other end.
The the cell body is the biosynthetic and communications center of the neuron. Like most regular cell bodies it has a plasma membrane, a nucleus, and celularl organelles in its cytoplasm. The nucleolus of the neuron nucleus is comparatively large and spherical in shape. Other cytoplasmic organelles include free ribosomes , a golgi apparatus facing the nucleus , rough endoplasmic reticulum(RER, Nissl granules) , mitochondria and a neurofibril network (microtubules) throughout the cytoplasm,
The dendrites constitute the input area of the neuron. They receive impulses and transmit them to the soma. The soma processes and transforms the impulse and passes on the product on to the axon which conducts it to the next neuron in the chain, or to an effector organ.
An accumulation of cell bodies, or perikarya, constitutes gray (grey) matter.
Work Step by Step
The neuron cell body is also called the soma or the perikaryon. It is the biosynthetic center of the neuron. It has a plasma membrane and within the enclosed cytoplasm it has all the regular cell organelles. The nucleus and nucleolus and are rather large, there are many mitochondria, and the golgi apparatus ( in the form of an arc facing the nucleus) is rather prominent. There are numerous free ribosomes and the RER is particularly well-developed. The soma synthesizes many proteins, and other molecules for cell body, and for the axon.
The axon hillock is an important part of the soma. Where the axon hillock tapers to meet the axon is called the trigger zone. This is the place were action potentials are often generated.
Cell bodies are located in the brain and spinal cord in the CNS, and in ganglia in the PNS.
The cerebral cortex, the cerebellar cortex, the thalamus, epithalamus, subthalamus and hypothalamus
and deep brain nuclei (caudate, raphe, olivary, and red nucleus) are all are constituted of gray matter. Gray matter is usually thought of as an accumulation of cell bodies. Howevwr, dendrites, short axons and small unmyelinated fibers are often included in gray matter.
