Page 4 - LN-NEURAL CONTROL & COORDINATION

b. Non-myelinated

In non-myelinated nerve fibres Schwann cell does not form myelin sheath
around the axon and are without nodes of Ranvier. They are commonly found
in autonomous and somatic neural systems.
Types of Neurons on the Basis of Structure
Based on the number of axon and dendrites, the neurons are divided into
three types
(i) Multipolar neurons These neurons have several dendrites and an axon. They
are found in cerebral cortex.

(ii) Bipolar neurons These neurons have one dendrite and one axon. They are
present in the retina of eye.
(iii) Unipolar neurons These neurons have cell body with one axon only. These
are found usually in the embryonic stage.
Main Properties of Neural Tissue
The neural tissue has two outsandingproperties
(a) Excitability It is the ability of nerve cells to generate an electrical impulse in

response to a stimulus by altering the normal potential difference across their
plasma membrane.
(b) Conductivity It is the ability of nerve cells to rapidly transmit the electrical
impulse as a wave from the site of its origin along their length in a particular
direction.
Functions of Neural System
The nervous system serves the following important functions
(i) Control and coordination Nervous system controls and coordinates the

working of all parts of the body so that it functions as an integrated unit. This is
achieved by three overlapping processes, i.e., sensory input, integration and
motor output.
(ii) Memory Nervous system stores the impressions of previous stimuli and
retrieves (recalls) these impressions in future. These impressions are referred
to as the experiences or memory.

(iii) Homeostasis Nervous system helps in the maintenance of the body’s
internal environment, i.e., homeostasis.
Generation and Conduction of Nerve Impulse
Nerve impulse is a wave of bioelectric/electrochemical disturbance that passes
along a neuron during conduction of an excitation.
Impulse conduction depends upon
(i) Permeability of axon membrane (axolemma).
(ii) Osmotic equilibrium (electrical equivalence) between the axoplasm and
Extracellular Fluid (ECF) present outside the axon.

The generation of a nerve impulse is the temporary reversal of the resting