Control and Coordination

CHAPTER – 7

Control and Coordination
Living organisms respond and react to various stimuli like heat, light, cold, touch, pressure etc. Plants and animals both respond to stimuli but in different manner.
Example : withdrawl of hand on touching a hot object.
Control and Coordination in Animals
It is brought about in all animals with the help of two main systems
a) Nervous System

b)

Endocrine System

Nervous System :
Functions
i)

To receive the information from environment

ii) To receive the information from various body parts. (Stimuli fi
Response)
iii) To act accordingly through muscles and glands.
Stimulus : Any change in environment or within that bring about the reaction eg: touching a hot plate.
Response : The reaction of our body to these changes. eg. withdrawal of our hand
How do we detect that we are touching a hot object?
Receptors : Are specialised tips of some nerve cells that detect the information from the environment.
Receptors
are
Sense Organs
Inner
Ear

Photo receptors
Eyes

Skin

Olfactory
Receptor
(Nose)

Gustatory
Receptor
(Tongue)

Hearing/
Balance of the body

Visual
Stimulus

Pain
Touch
Heat

Smell
Detection

Taste
Detection

63

X-Science

Neuron : Structural and functional unit of nervous system.
Neuron (3 main parts)
I

II

III

Dendrite

Cell body and Axon

Synapse

Information is acquired Information travels as an electrical impulse

Part where electrical signal is converted into chemical message for onward transmission to next neuron by release of neurotransmitters

Nucleus
Nerve
ending

Dendrite
Axon

Cellpody

Structure of neuron
Fig. 7.1 (a) P 115

Synapse : The point of contact between the terminal branches of axon of one neuron with the dendrite of another neuron is called synapse.
Reflex Action
A quick, sudden, immediate response of the body to the certain stimuli that involves Spinal cord. eg. (not brain)