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12 views22 pagesControl and Coordination 10
Chapter 7 discusses control and coordination in living organisms, highlighting how they respond to stimuli through body movements. In animals, this is managed by the nervous and endocrine systems, while in plants, it is regulated by phytohormones. The chapter also details the structure and function of the human nervous system, including neurons, the brain, and reflex actions.
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0% found this document useful (0 votes)
12 views22 pagesControl and Coordination 10
Chapter 7 discusses control and coordination in living organisms, highlighting how they respond to stimuli through body movements. In animals, this is managed by the nervous and endocrine systems, while in plants, it is regulated by phytohormones. The chapter also details the structure and function of the human nervous system, including neurons, the brain, and reflex actions.
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CHAPTER - 7
CONTROL AND COORDINATION la) Stimuli
The changes in the environment to which living
organisms respond are called stimuli.
Eg :- heat, cold, sound, smell, taste, touch, pressure,
gravity, water etc.
Living organisms respond to stimuli in the form of body
movements.
b) Coordination :-
For a proper response to a stimulus many organs in the
body should work together. The working together of
various organs in an organism to produce a proper
response to a stimulus is called coordination.
i) In animals control and co ordination is done by the
nervous system and endocrine system.
ii) In plants control and co ordination is done by chemical
substances called plant hormones or phytohormones.
@ 2) Coordination in anima
In animals control and co ordination
and endocrine system.
The nervous system consists of the brain, spinal cord and nerves.
a) Receptors :- are the sense organs which receive the stimuli and
pass the message to the brain or spinal cord through the sensory
nerves.
Eg :- Photoreceptors in the eyes to detect light.
Phonoreceptors in the ears to detect sound.
Olfactory receptors in the nose to detect smell.
Gustatory receptors in the tongue to detect taste.
Tangoreceptors in the skin to detect touch.
b)_Effectors :- are the muscles and glands which respond to the
formation from the brain and spinal cord through the motor nerves.
c) Sensory nerves :- are nerves which carry information from the
receptors (sense organs) to the brain and spinal cord.
d) Motor nerves :- are nerves which carry information from the brain
and spinal cord to the effectors (muscles and glands).
done by the nervous system HUMAN NERVOUS SYSTEM @
y ~~ 3) Human nervous system :-
a) Parts of the nervous system :-
The human nervous system consists of the Central Nervous System
and Peripheral Nervous System.
i) The central nervous system :- consists of the brain, and spinal
cord.
ii) The peripheral nervous system:- consists of cranial nerves
arising from the brain and spinal nerves arising from the spinal cord. CENTRAL NERVOUS SYSTEM
Brain PERIPHERAL NERVOUS SYSTEM
Centrat nerves
are in your
brain and
spinal cord
ERA
nerves go from
your brain to
your eyes,
mouth, ears,
and other
parts of
your head
nee-ud
Peripheral
(pune RIF-ub-rub,
nerves ge fram
your spinal cord
to your arms,
hands, leas,
and feat
Autonomic
(aw-tah- NOM ilk)
nerves go from
your spinal card
to your lungs,
heart, stornach,
and sex organs.
intestines, bladder,
@ b) Nerve cell (Neuron) :-
Neuron is the structural and functional unit of the nervous system. It
has a cell body called cyton containing a nucleus and cytoplasm. It has
several branched structures called dendrites. It has a long nerve fibre
called axon which is covered by a protective covering called Myelin
sheath. The junction between two neurons is called synapse.
Messages pass through the nerve cell in the form of chemical and
electrical signals called nerve impulse. The dendrites receive the
information and starts a chemical reaction which produce electrical
impulse which passes through the axon. ®
Dendrites Axon terminals
Structure of neuron (Nerve cell
Structure of a Typical Neuron
Node of ranvier
Cell body
Schwann's cells
Myelin sheath
Nucleus ®
n_ of messages through neurons ¢) Brain -
The brain is the main coordinating centre in the human body. It is
protected by the cranium. It is covered by three membranes called
meninges filled with a fluid called cerebrospinal fluid which protects
the brain from shocks.
The brain has three main parts. They are fore brain, mid brain and
hind brain. i) Fore brain :- consists of the cerebrum and olfactory lobes. It is the
thinking part of the brain and controls voluntary actions. It controls
touch, smell, hearing, taste, sight, mental activities like thinking,
learning, memory, emotions etc.
ii) Mid brain :- controls involuntary actions and reflex movements of
head, neck, eyes etc.
iii)
ind brain :- consists of cerebellum, pons and medulla.
Cerebellum :- controls body movements, balance and posture.
Pons :- controls respiration.
Medulla :- controls heart beat, blood pressure, swallowing, coughing,
sneezing, vomitting etc. HUMAN BRAIN HUMAN BRAIN d) Spinal cord :- @
The spinal cord starts from the brain and extends
through the vertebral column. It has 31 pairs of spinal
nerves.
It carries messages to and from the brain. It also
controls reflex actions.
Spinal cord
Medulla oblongata
|_cervieat
nerves
|_ Thoracic
| Lumbar
nerves
Coccygeal ‘Sacral nerves
nerves 4a) Reflex action :- @
Reflex action is a sudden, unconcious and involuntary
response of the effectors to a stimulus.
Eg :- We suddenly withdraw our hand if we suddenly
touch a hot object.
In this reflex action, the nerves in the skin (receptor)
detects the heat and passes the message through the
sensory nerves to the spinal cord. Then the information
passes through the motor nerves to the muscles (effector)
of the hand and we withdraw our hand. sensory neuron Seflex fre @®
interneuron in
spinal cord
a
motoF neuron
muscle
PNS CNS (rnuscie)_
The Pathway for a Reflex Action - the Reflex Arc REFLEX ACTION @
Cell body of
Sneiticens! sensory neuron in
idacie: dorsal root
ganglion
S
Spinal dora
(cross section)
@ Sensory neuron
@ Motor neuron
@ interneuron b) Reflex arc :-
The pathway of a reflex action is called reflex arc. Ina
reflex arc the stimulus is received by the receptors (sense
organs) and it passes through the sensory nerves to the
spinal cord. From the spinal cord the information passes
through the motor nerves to the effectors (muscles/glands)
for the response.
Stimulus
Receptors
(Sense organ)
sory A N
Spinal cord
Effectors
(Muscles/Glands)
Response
<+— _|Motor nerves
ra REFLEX ARC
A Reflex Arc Shows How Neuron Types Work Together.
Sensory cell body
‘The afferent and efferent
fibers often pass in the same
white matter
Integration
Sensory neuron
Stimus =>
Response