Which one of the following pairs of structures distinguishes a nerve cell from other types of cell?
Which one of the following pairs of structures distinguishes a nerve cell from other types of cell?
vacuoles and fibres
flagellum and medullary sheath
nucleus and mitochondria
perikaryon and dendrites.
Solution
A nerve cell consists of cell body (perikaryon) containing the nucleus, Nissl granules, dendrites and an axon. These are specialised cells meant for the transmission of the nerve.
Related Theory
The main functions of the myelin sheath in neuron are:
(I) It acts as an electrical insulator for the neuron.
(2) The sheath prevents the movement of ions into or out of the neuron, thus preventing depolarisation.
(3) It speeds up transmission of an electrical impulse in the neuron - impulses cannot travel through the sheath (the sheath acts as an electrical insulator), instead, impulses 'jump' from a gap in the myelin sheath to another gap (it jumps from one Node of Ranvier to another Node). This is a process called Saltatory Conduction.