Neuron
A neuron is a cell that transmit electrical signals. There are 3 types of neurons: motor, sensory and relay neuron. There are approximately 1011 neuron cells in the central nervous system of an individual. A typical neuron consists of a cell body, dendrites, axon and an axon terminal [1].
A neuron transmits electrical signals by action potentials. These are triggered when the cell receives a chemical signal, such as the one from Acetylcholine binding to the post synaptic membrane, causing Sodium voltage-gated ion channels to open and Sodium to diffuse down its concentration gradient into the neuron causing depolarisation (an electrical signal).
A nerve cell consists of a cell body with dendrites and a nucleus, an axon which is surrounded by a myelin sheath which passes the nervous signal along to axon terminals. Synapses with other cells occur at the dendrites and axon terminals, stimuli (e.g. chemical or electrical) cause the nerve to depolarise and an action potential is produced. Once at the axon terminals the signal can be transferred to neighbouring nerve cells or effector cells by a chemical neurotransmitter e.g. acetylcholine. A high temperature, large axon diameter and the presence of a myelin sheath increase the rate at which the signal is transmitted along the axon. [2]
References:
- ↑ Developmental Biology, 8th Edition, Scott F. Gilbert, Pg 394
- ↑ http://hyperphysics.phy-astr.gsu.edu/hbase/biology/nervecell.html#c2
- ↑ http://www.naturalhealthschool.com/9_2.html