Co – Ordination

Co – Ordination
Definition
The working together of all parts of the body or system is called Co-ordination.
Types of Co-Ordination
There are two types of Co-ordination.
1. Nervous Co-Ordination
2. Chemical Co-Ordination
1. Nervous Co-Ordination
Definition
Co-Ordination brought about by the nervous system. It is quickest way of communication take place by electro-chemical messages called Nerve Impulse within the body of all animals is called Nervous Co-Ordination.
Elements of Nervous System
The elements o nervous system which help in co-ordination are
i. Receptor
ii. Central Nervous System (CNS)
iii. Effector
i. Receptor
The sensory tissues or organs which receive any change in their external as well as internal environment (stimuli) are called Receptors.
ii. Central Nervous System
The receptors convey the stimuli to the control centre, the nervous system (Central Nervous System) through sensory nerves.
iii. Effector
The central nervous system (CNS) analyses stimuli and sends an appropriate command, through it motor nerves to either endocrine organ to release hormones into the blood or to muscles called Effectors.
Pathway in Nervous System
There are two types of pathway in the nervous system.
i. Afferent Nerve Pathway
ii. Efferent Nerve Pathway
i. Afferent Nerve Pathway
From receptor the messages are carried to the Central Nervous System i.e. brain and spinal cord, this pathway is called Afferent Nerve Pathway.
ii. Efferent Nerve Pathway
From central nervous system the messages are transferred to the effector. This pathway is called Efferent Nerve Pathway.
Nervous Tissues
There are two types of nervous tissues
1. Neurons
2. Neuroglia OR Glial Cells
1. Neurons

Definition
The nervous system consist of special cells which can generate and conduct electric current are called Neurons.
OR
The chief structural and functional unit of nervous system is called Neurons.
Structure of Neurons
Neurons are different from each other according to size and shape but the structure of neuron consists of three parts.
i. Some or Cell Body
ii. Dendrites
iii. Axon
i. Soma OR Cell Body
Each neuron has a cell body or soma containing nucleus and various organelle embedded in the cytoplasm. Nissl’s granules which are group of ribosomes, associated with rough E.R. and Golgi apparatus are present in the cell body.
Functions
The cell body or soma is the main nutritional part of the cell necessary for growth of neuron.
Soma receive message to dendrites and convey it to axon.
ii. Dendrites
From the soma, a large number of small threads like terminal branches are arises are called Dendrites.
Functions
Dendrites receive stimuli and convey it to the soma.
iii. Axon
The unbranched, single elongated cytoplasm process which usually arises opposite to dendrites called Axon.
Axon Hillock
Axon originates from a pyramid like area of soma called Axon-Hillock.
Axon Terminal
At the terminal end of axon many fine branches are present called Axon Terminals.
Myelin Sheath
The axon of some neurons is enclosed by a layer of fatty substance known as Myelin Sheath.
This serve as insulating layer.
Functions
Axon is specialized for conducting impulses to other neurons.
Types of Neurons
According to the function, neurons are of the three types.
i. Sensory Neuron
ii. Motor Neuron
iii. Inter Neuron
i. Sensory Neuron
The neurons which transmit impulses from receptor to the central nervous system is called Sensory Neuron or Receptor Neurons.
ii. Motor Neuron
The neurons which transmit instructions of the central Nervous System to the effector are called Motor Neurons or Effector Neurons.
iii. Inter Neurons
The neurons present between sensory and motor neurons are called Inter Neurons. They are found in Central Nervous System.
Functions of Neurons
Neurons is the functional unit of nervous system which receives stimuli, transfers them to the Central Nervous System (CNS).
It transfers the messages from CNS to the body parts effector.