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 Photo receptors Skin Olfactory Gustatory
Ear Eyes Receptor Receptor
(Nose) (Tongue)
Hearing/ Visual Pain Smell Taste
Balance of Stimulus Touch Detection Detection
the body Heat
63 X-Science
, Neuron : Structural and functional unit of nervous system.
Neuron (3 main parts)
I II III
Dendrite Cell body Synapse
and Axon
Information is Information Part where
acquired travels as an electrical signal
electrical impulse is converted into
chemical message
for onward transmission
to next neuron
by release of neurotransmitters
Nucleus
Nerve
Dendrite ending
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) withdrawal of hand, knee jerk etc.
Reflex arc : The pathway through which impulses pass is called reflex arc.
64 X-Science
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 Photo receptors Skin Olfactory Gustatory
Ear Eyes Receptor Receptor
(Nose) (Tongue)
Hearing/ Visual Pain Smell Taste
Balance of Stimulus Touch Detection Detection
the body Heat
63 X-Science
, Neuron : Structural and functional unit of nervous system.
Neuron (3 main parts)
I II III
Dendrite Cell body Synapse
and Axon
Information is Information Part where
acquired travels as an electrical signal
electrical impulse is converted into
chemical message
for onward transmission
to next neuron
by release of neurotransmitters
Nucleus
Nerve
Dendrite ending
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) withdrawal of hand, knee jerk etc.
Reflex arc : The pathway through which impulses pass is called reflex arc.
64 X-Science
