Control and co ordination

1. CONTROL AND CO-
ORDINATION

2. • Working together of various integrated body systems in
response to changes in the surrounding for the maintenance of
bodily functions is known as Control and Coordination.
• Nervous system and endocrine system provide control and
coordination in animals.

3. TERMINOLOGY
• Stimuli: The changes in the environment to which living
organisms respond are called stimuli. Eg. Heat, cold, sound,
smell etc.
• Coordination: For a proper response to a stimulus many organs
should work together. This is called coordination.
• - In animals control and coordination is done by the nervous
and endocrine systems.

4. TERMINOLOGY
• The nervous system consists of brain, spinal cord and nerves.
• Receptors: are the sense organs that receive the stimuli and
pass the message to the brain or spinal cord through the
sensory nerves.
• Effectors: are the muscles and glands which respond to the info
from the brain and spinal cord through the motor nerves.

5. • Sensory neurones: are the neurones that carry info from the
receptors (sense organs) to the brain and spinal cord.
• Relay neurones are found between sensory input and motor
output /response. Relay neurones are found in the brain and
spinal cord and allow sensory and motor neurones to
communicate.
• Motor neurones: are the neurons that carry info from the brain
and spinal cord to the effectors (muscles and glands).

7. NEURONE
• Neurone is the structural and functional unit of the nervous
system.

8. FUNCTIONS
• Dendrites are tree-like extensions at the beginning of a neuron that
help increase the surface area of the cell body. These tiny protrusions
receive info from other neurones and transmit electrical stimulation
to the soma or cell body.
• The cell body is where the signals from the dendrites are joined and
passed on. The cell body contains numerous organelles and a
nucleus too.
• The axon is the elongated fiber that extends from the cell body to
the terminal endings and transmits the neural signal. The larger the
axon, the faster it transmits info. Some axons are covered with a fatty
substance called myelin sheath that acts as insulator. The axon
transmits info away from the cell body.

9. SYNAPSE
• The end of one neurone is not connected to the next. There is
always a small gap between them. The gap is called a synapse.
• An impulse reaching the end of an axon, produces a chemical
called neurotransmitter. This diffuses across the gap and binds
with receptor molecules in the membrane of the next neurone.

10. SYNAPSE
• A resistor: It may take a number of impulses before enough
neurotransmitter is made to start the impulse in the next
neuron.
• A junction box: one neuron may pass on its impulse to a
number of other neurons.

11. REFLEX ARC

12. REFLEX
• A reflex, or reflex action, is an involuntary and nearly
instantaneous movement in response to a stimulus

13. HOW DOES A NERVE IMPULSE TRAVEL?
• The dendrite end of a neurone collects information and triggers a
chemical reaction, which results in an electric impulse.
• The impulse is transmitted from the dendrite to the cell body and
then to the axon.
• From the axon, the impulse travels to its end, where the electrical
impulse sets off the release of some more chemicals, called
neurotransmitters.
• The chemicals cross the synapse and start a similar electrical impulse
in the dendrite to the next neurone. Thus the impulses are
transmitted from one neurone to another.

15. • Hypothalamus links the nervous system to
the endocrine system via the pituitary gland. It produces
'inhibitory hormones' and 'releasing hormones' - It regulates
the secretion of hormones from pituitary gland.

16. SENSE ORGANS
• The skin responds to touch, pressure pain etc
• The tongue responds to chemicals in our food and drink and
gives sense of taste.
• The nose responds to chemicals in the air and gives sense of
smell.
• The ears respond to sound vibrations and movements and give
sense of hearing and balance.
• The eyes respond to light rays and give sense of sight.

18. • Lights enters eyes through cornea. It then passes through the
pupil. This is surrounded by the coloured iris.
• At the front of the cornea is the transparent and delicate layer
called conjunctiva. It is kept moist by tear glands.

19. PUPIL REFLEX
• Two sets of muscles are involved:
• The circular muscles are arranged around the pupil and
• The radial muscles run outwards from the pupil like the spokes
in a wheel.
• Their job is to regulate the intensity of light that reaches the
sensitive retina.

20. • In low light, the circular muscles relax and the radial muscles
contract. This dilates the pupil, so that more light can reach the
retina.
• In the dark, just the opposite takes place.

21. HOW DO WE SEE THINGS?
• In the retina there are photosensitive cells called rods and
cones.
• When light stimulates them they send impulses to the brain
along the optic nerve. Your brain interprets these impulses to
make a picture.
• The image on the retina is inverted but our brain has learnt to
turn it right way

22. • In the retina, rod cells respond to dim light and cone cells
detect colour and details.

23. HOW DO WE FOCUS ON OBJECTS THAT ARE
NEAR OR FAR?
• If you are looking at a distant object:
• The ciliary muscles relax
• - This tightens the suspensory ligaments
• - so the lens is pulled into thin shape
• - the distant object is focused on the retina

24. • If you are looking at a near object:
• The ciliary muscles contract
• - this slackens the suspensory ligaments
• - So the elastic lens goes fatter
• - the near object is focused on the retina

26. SHORT SIGHT/MYOPIA AND LONG
SIGHT/HYPERMETROPIA