What is axonal hillock?
The axon hillock is a specialized part of the cell body (or soma) of a neuron that connects to the axon. It can be identified using light microscopy from its appearance and location in a neuron and from its sparse distribution of Nissl substance.
What is the Perikaryon of a neuron?
The soma (pl. somas), perikaryon (pl. perikarya), neurocyton, or cell body is the bulbous, non-process portion of a neuron or other brain cell type, containing the cell nucleus. The word ‘soma’ comes from the Greek ‘σῶμα’, meaning ‘body’.
What is inside the soma?
The Soma (Latin, som / a: body) or cell body of a neuron contains the nucleus and other structures common to living cells. These structures support the chemical processing of the neuron; the most important of which is the production of neurotransmitters.
What is the axon hillock made of?
The axon hillock may contain fragments of Nissl substance, including abundant ribosomes, which diminish as the hillock continues into the initial segment. Here, the various axoplasmic components begin to align longitudinally. A few ribosomes and the smooth ER persist, and some axoaxonic synapses occur.
What are collaterals in neurons?
An axon typically develops side branches called axon collaterals, so that one neuron can send information to several others. These collaterals, just like the roots of a tree, split into smaller extensions called terminal branches. Each of these has a synaptic terminal on the tip.
Is the perikaryon the same as soma?
The soma (pl. somata or somas) is also known as a perikaryon (pl, perikary), a cyton, or simply as a neuron cell body. The word “soma” comes from the Greek σῶμα, meaning “body,” while perikaryon comes from peri, meaning “around” and kary, meaning “nucleus.”
Are neurons Amitotic?
Neurons, or nerve cells, carry out the functions of the nervous system by conducting nerve impulses. They are highly specialized and amitotic. This means that if a neuron is destroyed, it cannot be replaced because neurons do not go through mitosis.
What did Cajal discover?
Cajal’s work led to the conclusion that the basic units of the nervous system were represented by individual cellular elements (which Waldeyer christened as “neurons” in 1891). This conclusion is the modern basic principle of the organization of the nervous system.
What is the myelin sheath?
Myelin is an insulating layer, or sheath that forms around nerves, including those in the brain and spinal cord. It is made up of protein and fatty substances. This myelin sheath allows electrical impulses to transmit quickly and efficiently along the nerve cells.
Is soma same as cell body?
The region of the neuron containing the nucleus is known as the cell body, soma, or perikaryon (Figure 8.2). The cell body is the metabolic center of the neuron.