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
 Stimulus RECEPTOR Sensory Nerves
› ORGAN
eg. Heat (SKIN)
Spinal Cord

Response EFFECTOR
› ORGAN Motor Nerves
eg. Withdrawal (MUSCLE)
of
Hand
Refer to diagram Fig 7.2 Reflex arc

Response
Responses are of three main types
Voluntary : Controlled by fore brain
eg. Talking, Writing
Involuntary : Controlled by mid and hind brain
eg. Heart beat, vomiting, regulation of heartbeat
Reflex action : controlled by spinal cord
eg. Withdrawl of hand on touching a hot object.
Human Nervous System

Central Nervous Peripheral Autonomic

System Nervous Nervous
System System
(CNS (PNS) (ANS)

Brain Spinal Cranial Spinal Sympathetic Para

Cord. Nerves Nerves Nervous Sympathetic
System Nervous
Fore Brain Arise from Arise from System
Mid Brain the brain Spinal Card

Hind Brain

65 X-Science
 Human Brain
Human brain has three major parts or regions
a) Forebrain b) Mid Brain c) Hind Brain
FOREBRAIN
Most complex/specialized part of the brain is CEREBRUM

FUNCTIONS :
1. Thinking part of the brain
2. Control the voluntary actions.
3. Store information (Memory)
4. Centre associated with HUNGER
5. Receives sensory impulses from various body parts and integrates it
Mid Brain :
HYPOTHALAMUS : Chemical co-ordination
PITUITARY GLAND : Secretes hormones
Hind Brain :
CEREBELLUM i) Controls posture and balance
ii) Control precision of voluntary actions
MEDULLA Controls involuntary actions
eg. blood pressure, salivation, vomiting
PONS Involuntary action, regulation of respiration

Fig 7.3 Human Brain

66 X-Science
 PROTECTION OF BRAIN AND SPINAL CORD
Brain : Brain is protected by a fluid filled balloon which acts as shock
absorber and enclosed in cranium (Brain Box)
Spinal Cord : Spinal Cord is enclosed in Vertebral column.

Coordination between Nervous and Muscular Tissue

Information Central Information
[collected by Nervous Processed
Nervous tissue] System by
(Sensory Nerve) [CNS] [CNS]

Action Decesion
made
[by CNS]
Muscle shorten (Motor Nerves)
Message
Contraction Muscles Passed to
[Muscle cell] [Change in shape muscles
and arrangement
of proteins]
Coordination in Plants
Movement in Plants

Movement dependent Movement independent

on growth of growth
[immediate response
to stimulus]
Tropic movements eg. dropping of leaves
[directional movements of Touch-me-not
in response to stimulus] plant on touching it

Phototropism Geotropism Chemotropism Hydrotropism

Movement Movement Movement Movement

towards light towards gravity towards Chemicals/ towards /
growth of pollen water
tube towards avule

67 X-Science
Plant hormones :
Are chemical compounds which help to coordinate growth, development and
responses to the environment.
Plant hormones : Main plant hormones are :
a) Auxin : [Synthesized at shoot tip]
Function : – Helps in growth
Phototropism : more growth of cells towards light.
b) Gibberellin : Helps in the growth of the stem
c) Cytokinins : Promotes cell division
d) Abscisic acid : Inhibits growth, cause witting of leaves.
(Stress hormone)
Hormones in Animals
Hormones : These are the chemical messengers secreted in very small amounts by
specialised tissues called ductless glands. They act on target tissues/organs usually
away from their source.
Endocrine System helps in control and coordination through chemical compounds
called HORMONES

68 X-Science
 S. Hormone Endocrine Location Functions
No. Gland

1. Thyroxine Thyroid Neck/ Regulation of metabolism

Throat of carbohydrates, fats
region and proteins.

2. Growth Pituitary Mid Regulates growth and

hormone development.

3. Adrenaline Adrenal Above Regulation (increasing)

both of blood pressure, heart
kidneys heat, carbohydrate
metabolism (during
emergency)
G

{
4. Testosterone Testes O
Genital/ Changes associated
SEX in Males N lower with puberty
Hormone A abdomen (Sexual maturity)
D
estrogen Ovaries S area

5. Insulin Pancreas Below Reduces and regulates

stomach blood sugar level

IODISED SALT IS NECESSARY BECAUSE :

Iodine mineral is essential part of thyronine hormone so it is important that we
must consume iodised salt as in turn it is essential for thyroid gland as it controls
carbohydrate, proteins and fat metabolism for best balance of growth deficiency of
iodine might cause disease called goitre
Diabetes :
Cause : It is due to deficiency of Insulin hormone secreted by Pancreas that is
responsible to lower/control the blood sugar levels.
Treatment : Patients have to internally administer injections of insulin hormone
fiwhich helps in regulating blood-sugar level.
Feedback Mechanism
fi makes sure that hormones should be secreted in precise quantities and at right
time, which is regulated by feedback mechanism.

69 X-Science
 Sugar level in the blood rises
SWITCH OFF
Feedback sent
Detected by cells of Pancreas

Synthesis insulin

Blood sugar level falls

(like a float in watertank)
Stop secreting more
insulin

EXERCISE
(Question Bank)
Very Short Answers (1 Mark)
1. Where is auxin synthesized in plants?
2. Which gland is known as Master gland?
3. Name the hormone that regulates blood sugar level.
4. What is synapse.
5. What are tropic movements? Give one examples
6. Define hormones
7. Which hormone has inhibiting effect on growth of plants
8. What is phototropism?
9. What are the components of central Nervous System.
10. What happens at synapse between two neurons.
Short Answers (2 Marks)
1. Draw diagram of neuron and label cell body, dendrites and axon.
2. What is reflex arc? Explain with the help of a flow-chart.
3. Mention one function of each of the following
i) Cerebellum
ii) Pons.
4. What is the cause of diabetes? How it can be controlled.
5. Why it is advisable to use iodised salt.

70 X-Science
6. What are the different receptors present in our body? What are their
functions.
7. What are plant hormones? Name a plant hormone that promotes growth in
plants.
8. What are sensory and motor neurons? Write their functions.
Long Answers (5 Marks)
1. What are hormones (in animals) List four characteristics of hormones. Name
the hormone required for the following.
i) Development of moustache and beard in human male
ii) Lowering of blood glucose.
2. Mention the functions of
a) Fore brain
b) Mid brain
c) Hind brain

71 X-Science
 Control and Coordination

IN CHAPTER QUESTIONS

PART - 1

Q1. What is the difference between a reflex action and walking?

Ans. Reflex action Walking

1. Reflex action is the immediate and involuntary Walking is a voluntary action

action which is controlled.

2. It is conducted by the spinal cord. It is controlled by hind-brain

(by cerebellum )

3. It occurs in a fraction of seconds. It takes longer time.

Q2. What happens at the synapse between two neurons ?

Ans. The neurons lie end to end in a chain to transmit the impulses in an animal body. The neurons are
not connected. There occurs a very minute gap between terminal portion of axon of one neuron
and dendron of the other neuron. This gap is called synapse. At the end of the axon, the electrical
impulse sets off the release of some chemicals. These chemicals cross the gap (synapse), and
start a similar electrical impulse in dendrite of the next neuron.
Synapses actually act like one way valves. This is because the chemical substance is present
at only one side of the gap. In this way synapses ensures that nerve impulse travels only in one
direction.

Q3. Which part of the brain maintains posture and equilibrium of the body?
Ans. Cerebellum.

Q4. How do we detect the smell of an agarbatti (incense stick)?

Ans. When agarbatti burns, its pleasant small is detected by the olfactory receptor present inside the
nose.The action of smell generate the electrical impluse which are carried to hypothalamus of
brain thus we detect the smell of agarbatti.

Q5. What is the role of the brain in reflex action?

Ans. The reflexes which involve only the spinal cord are called spinal reflexes.The spinal reflexes
are produced in the spinal cord but the message of reflex action taken also goes to reach the
brain where the thinking process occurs. Some reflex arcs involve the brain, rather than the
spinal cord only.They are called cerebral reflexes.Closing of eyes, when exposed to flash of
light and salivation at the sight of tempting food, are the examples of cerebral reflexes.

1
 Control and Coordination

PART - 2

Q1. What are plant hormones?

Ans. Plant hormones help to coordinate growth, development and response to the environment. They
are synthesized in minute quantity in one part of the plant body and simply diffuse to another
part, where they influence specific physiological processes. Example Auxins.

Q2. How is the movement of leaves of the sensitive plant different from the movement of a shoot
towards light?
Ans.

movement of a shoot towards light movement of leaves of the sensitive plant

Direction of movement is in the Movement are non directional.
direction of the stimulus.
Growth takes place. Growth does not take place.
Movements are slow. Movements are fast.

Q3. Give an example of a plant hormone that promotes growth.

Ans. Auxins

Q4. How do auxins promote the growth of a tendril around a support?

Ans. When the tip of the tendril touches a support, the auxins present on its tip moves to the side of
tip which is away from the support, so due to more auxins in its tendrils away from the
support grows faster.

Q5. Design an experiment to demonstrate hydrotropism.

Ans. Aim : To demonstrate that root shows hydrotropism.
Method
Place germinating seeds in moist saw dust contained in a sieve.
Observation
(i) The radicles pass down and come out of the sieve pores under the influence of gravity.
(ii) After some growth, radicles move back and enter the saw dust again.
Conclusion
(i) This shows that roots shows both hydrotropic response and geotropic response.
(ii) The hydrotropic response of root are stronger than geotropic response.

2
 Control and Coordination

PART - 3

Q1. How does chemical coordination take place in animals?

Ans. Hormones –They are secretions of the endocrine glands and one of the most important
substance that controls the body chemistry, also known as "Chemical messengers."

Q2. Why is the use of iodised salt advisable?

Ans. Iodine is important for the thyroid gland to make thyroxin hormone. Thyroxine regulates
carbohydrates, proteins and fat metabolism in the body so as to provide the best balance for
growth. If iodine is deficient in the diet, thyroxine cannot be produced and the thyroid gland at
the neck swells, a condition called goitre. Use of iodized table-salt can provide the required
amount of iodine in the diet.

Q3. How does our body respond when adrenaline is secreted into the blood?
Ans. Adrenal glands release adrenaline into blood.
(i) The heart begins to beat faster resulting in supply of more oxygen to the muscles.
(ii) The blood to the digestive system and skin is reduced due to the contraction of smooth
muscles around small arteries in these organs.This diverts the blood to our skeletal
muscles.
(iii) The breathing rate increases because of the contraction of the diaphragm and the rib
muscles.
(iv) All these responses together enable the body to be ready to deal with the situation.

Q4. Why are some patients of diabetes treated by giving injections of insulin?
Ans. This is a hormone which is produced by the pancreas and helps in regulating blood sugar
levels. If it is not secreted in proper amounts, the sugar level in the blood rises causing many
harmful effects.

3
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 Control and Coordination
EXERCISES
Q1. Which of the following is a plant hormone?
(A) Insulin
(B) Thyroxin
(C) Oestrogen
(D) Cytokinin.
Ans. (D) Cytokinin.

Q2. The gap between two neurons is called a

(A) dendrite.
(B) synapse.
(C) axon.
(D) impulse.
Ans. (B) synapse.

Q3. The brain is responsible for

(A) thinking.
(B) regulating the heart beat.
(C) balancing the body.
(D) all of the above.
Ans. (D) all of the above.

Q4. What is the function of receptors in our body ? Think of situations where receptors do not work
porperly. What problems are likely to arise ?
Ans. All information from environment is detected by receptors. Receptors pass information in the
form of electrical impulses to brain by nerve cells and brain send information to effector organs
for response. When receptors do not work properly, information from environment (stimuli) cannot
be detected and our body cannot respond accordingly.

4
 Control and Coordination
Q5. Draw the structure of a neuron and explain its function.

Ans.

Function of a neuron :
(i) It helps in conducting impulses which enables the organism to show responses towards the
stimuli.
(ii) It helps in regulating control and coordination in animals.

Q6. How does phototropism occur in plants ?

Ans. The response of a plant towards light is called as phototropism. If the plant part moves
towards light, it is called positive phototropism. however, if the plant part moves away
from light, then it is called negative phototropism.
The stem (or shoot) of a growing plant bends towards light, so the stem (or shoot) of plant
shows positive phototropism. On the other hand, the roots of a plant move away from
light, so the roots of a plant show negative phototropism.

Q7. Which signals will get disrupted in case of a spinal cord injury ?
Ans. Spinal cord is an important component of Central Nervous system. It serves as a two way
conduction path between peripheral nervous system and brain. The controlling centres in different
areas of spinal cord function as reflex centres which control all the spinal reflexes. An injury
in the spinal cord will disrupt the reflexes. The part of the body affected will depend upon the
region where the spinal cord is injured. It may be neck, thoracic or abdominal region.

Q8 How does chemical coordination occur in plants ?

Ans. It is necessary that all parts of body of an organisms work together to give correct movement
in response to the stimuli. So living organisms must use system providing control and coordination.
In higher organisms nervous system and endocrine system together perform this function And
in plants phytohomones coordinate movement, growth etc.

Q9. What is the need for a system of control and coordination in an organisms ?
Ans. Multicellular organisms have diverse structure and functions. There are different system which
perform specific function but the functioning of one system is not independent from the other.
There is integration of all functional acitivities of the organism. For example, digestive enzymes
are secreted into the food canal only when there is a food.
The integration is possible because of communication and control. Communication makes control
possible. The control and coordination occurs by two systems, i.e.,

(i) by the release of chemical messengers called the hormones from endocrine system
(ii) by the conduction of nerve impulse, i.e. nervous system.

5
 Control and Coordination
Q10. How are involuntary actions and reflex actions different from each other ?
Ans. Reflex actions are sudden, unconscious automatic response to some change in environment. It
is controlled by spinal cord. On the other hand, involuntary actions also occur without the will
of animals but these actions are controlled by either mid brain or hind brain.

Q11. Compare and contrast nervous and hormonal mechanisms for control and coordination in animals.
Ans.

Q12. What is the difference between the manner in which movement takes place in a sensitive plant
and the movement in our legs ?
Ans. Movement takes place in sensitive plant due to turgor changes (changes in amount of water)
which is effected by phytohormones. But movement in our leg is a voluntary action under the
control of our will. Such movement are controlled by hind brain.

6
NAVODAYA VIDYALAYA SAMITI, NOIDA
E-CONTENT PREPARATION FOR
CLASS X SCIENCE
CHAPTER 7
CONTROL AND COORDINATION
Prepared by
MRS SIMI C NAIR, PGT BIOLOGY,
JNV CHITRADURGA,KARNATAKA
 CONTROL AND COORDINATION
Learning Outcomes
Students will be able to:
I . Define reflex action, Tropic and Nastic movements.
ii. Identify the different parts of the brain.
iii. Differentiate the different types of nerves based on structure and
function.
iv. Understand the communication between CNS and parts of the body
and the mechanism of reflex action.
Vi. Acquire knowledge about the structure and function of nervous
system in animals and coordination in plants.
Vii .Appreciate the role of feedback mechanism of endocrine system in
our life.
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.
Coordination :-
. 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
ANIMAL NERVOUS SYSTEM AND COORDINATION

In animals control and co ordination is done by the

nervous system and endocrine system.
The nervous system consists of the brain, spinal
cord , nerves and sense organs.

Sense Organs: Eyes, Skin, Ears, Nose & Tongue

 Coordination by Brain

Stimulus Receptor Coordinator Effector

Sense organs Muscles

Brain
Sound, sight, like, ears, Response
smell, taste, nose, eyes etc
pain or touch

Movement on the basis of type

of stimuli
 THE NEURON
• Nervous system is made of
millions of neurons
• A nerve is an organ containing
a bundle of nerve cells called
neurons.
• Neurons carry electrical
messages called impulses
throughout the body.
• Impulse travels from dendrite
to cell body, then along axon to
axon terminal
SYNAPSE
Because neurons never touch, chemical signallers called
neurotransmitters must travel through the space called
synapse between two neurons.
. Neurotransmitters
The
message is
transferred
when
RECEPTORS
receive
neurotransmit
ters
(pink
spheres)
Synapse (gap)
 IMPORTANT TERMS a bundle of nerve cells called
• a) Receptors :- are the specialized tips of nerve cells 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
information from the brain and spinal cord through the motor nerves.
• c) Response - Any behavior of a living organism that results from an
external or internal stimulus. (e.g. pulling hand away from a hot
plate is a response)
. d) Sensory nerves :- are nerves which carry information
from the receptors (sense organs) to the brain and spinal
cord.
• e) Motor nerves :- are nerves which carry information from
the brain and spinal cord to the effectors (muscles and
glands)
 TYPES OF NEURONS

Interneuron
Sensory Neuron
Synapse
Synapse
Interneuron
Motor Neuron

Motor Neuron Synapse

Muscle Contracts
Sensory Neuron
 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.
 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.
 HUMAN 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) Hind 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
 SPINAL CORD
• The spinal cord starts from the brain and
extends through the vertebral column.
• It carries messages to and from the brain.
It also controls reflex actions.
CRANIUM AND VERTEBRAL COLUMN
• Brain which is a delicate organ is
protected inside a bony box.
• Inside the box brain is contained in a fluid
filled balloon which provides shock
absorption
• Vertebral column protects the spinal cord
 CO ORDINATION IN PLANTS
• In animals, control
and coordination
in governed by the
nervous system.
However, plants do
not have a nervous
system.
• how do plants respond to
stimuli
• Plants respond to stimuli
by showing movement.
SEEDLING GROWTH
• when you touch a sensitive plant such a
touch-me-not(Mimosa pudica), the plant
folds its leafs.
Shoot grows upwards
• When a seed germinates, the root grows
down in the soil and stem grows up .
• In the first example, by responding to the
stimuli (touch) shows movement by
folding leafs.
• In second example, the seed germinates
and shows directional movement.
• In first example, movement is
independent of growth. However, in the Root goes downward
second example, growth is dependent of
growth.
• Thus,plants exhibit both growth-dependent
 6) Movements in plants :-
Movements in plants are of two main types. They are :-Tropic
movements and Nastic movements.
a) Tropic movements :- are directional movements towards or
away from the stimulus and it depends on growth. They are of
different types like phototropism, Geotropism, chemotropism,
Hydrotropism etc.
• i) Phototropism :-

• Movement of plants in response to light.

If it is towards light, it is called positive
phototropism.
• Eg:- Bending of shoot towards light.
• If it is away from light, it is called
negative phototropism.
• Eg:- Bending of root away from light.

• ii) Geotropism :-
• Movement of plants in response to
gravity. If it is towards gravity it is
called positive geotropism. Eg:-
Downward growth of roots.
• If it is away from gravity it is called
negative geotropism.
• Eg:- Upward growth of shoot.
iii) Chemotropism :- is
movement of plant in response
to chemical stimuli.
Eg:- Growth of pollen tube
towards the ovule.
iv) Hydrotropism :- is the
movement of plants in
response to water.
Eg :- Growth of roots
towards water.

CHEMOTROPISM
b) Nastic movements :-
Non directional movements
which are neither towards or away
from the stimulus and it does not
depend on growth.
Eg :- If we touch the leaves of
touch me not plant, its leaves fold
up and droops down immediately
due to the change in the amount of
water in the leaves. Depending
upon the amount of water in the
leaves, it swells or shrinks
• Plants respond to stimulus by some chemical changes as in case of
Mimosa pudica. It is very quick movements.
• Immediate response such as in Mimosa the information is
transferred by electrochemical changes from cell to cell and the
movement occurs by change in cell size by osmosis.
• In normal condition the cell remains turgid and maintains
normal posture but as a stimulus received the cells stars
exosmosis as a result water comes out of the cells and
shrinks in size.
• Chemical Coordination
• The electrical impulses of
nervous system have
limitations as it does not
associate with each and every
cell and it require a resting
period before setting a new
impulse.
• So there is a need of having a
system in which cell secretes
some chemicals which can
diffuse all around it and be
detected by other cell’s
receptors and even transmitted
by them also.
• Hormones
• These are chemical messengers which are secreted by
endocrine glands and released directly into the blood from
where they can reach to the target organ and show their effect.
• They are secreted in very small quantity by glands and act upon
specific cells, tissues, or organs called target sites
• They are slow in action and have long lasting effects.
• Plant Hormones
• In plants, growth, development,
and response to the
environment is controlled and
coordinated by naturally
occurring organic chemical
substances known as
Phytohormones/plant
hormones.
• These hormones are produced
in one part of the plant body in
minute quantities and and
diffuse/ translocate to other
parts as required.
 Auxins:
• When the growing parts of a phototropic plants detect sunlight, auxins
(synthesized at the shoot tips) help the cells grow longer. When light
falls on one side of the plant, the auxins generally diffuse towards the
shaded side of the shoot. This stimulates the cells in the shaded area to
grow longer than the corresponding cells of the illuminated region. This
results in the curvature of the plant stem tip towards light
• Cytokinins:It promotes cell division and are present in greater
concentration in those areas of the plants where rapid cell division
occurs, such as in fruits and seeds
Gibberellins:It helps in growth of plant in length. They promote stem
elongation by promoting cell division in the inter-nodal region.
• Abscisic Acid:It inhibits growth,causes wilting of leaves and also
induces Dormancy (period in which no growth occurs during
unfavorable conditions)
 Animal Hormones
These are secreted by endocrine glands
in animals. Some important glands are:
•Hypothalamus:
Situated in brain it releases some factors
which control the secretions of pituitary
gland.
•Pituitary Gland:
it is also situated in brain and is known
as Master Gland of the Body. Its
secretions control the other endocrine
glands and regulate them. It also
produces Growth hormone which
regulates growth and development of
the body. Deficiency of this can cause
dwarfism
ENDOCRINE GLANDS IN HUMAN BEINGS

Thyroid:
It secretes Thyroxin which
controls the metabolism of
carbohydrates, fats and
proteins. Iodine is essential
for synthesis of thyroxin so
deficiency of iodine in diet
will cause goitre disease
having symptom of swollen
necks.
 • Pancreas:
• It secrete Insulin hormone which
control blood sugar level. If not
secreted in enough quantities it
will lead to Diabetes(rise of sugar
level in blood).
• Gonads(Sex organs):
• In males, Testes secrete
Testosterone and in females
,Ovaries secrete Oestrogen and
progesterone which control sex
organs and sexual characteristics
during puberty
 • Adrenal:
• It secrete Adrenalin hormone which
regulates heart beat to maintain
proper oxygen supply in emergency
condition .The muscles around small
arteries to digestive system and skin
contract and blood flow increases to
skeletal muscles. Thebreathing rate
also increases enabling body to
deal with emergencies
.
 IMPORTANT E-LINKS FOR RESOURCE MATERIAL
❖ https://www.learncbse.in/control-coordination-chapter-wise-important-ques
tions-class-10-science
❖ https://www.jagranjosh.com/articles/control-and-coordinationimportant-que
stions-preparation-tips-1372336848-1
❖ https://www.khanacademy.org/science/in-in-class-10-biology
❖ https://play.google.com/store/apps/details?id=in.gov.epathshala&hl=en_IN
❖ https://mycbseguide.com/blog/ncert-solutions-for-class-10-science-control-a
nd-coordination-part-1/
❖ https://www.youtube.com/watch?v=HZh0A-lWSmY
❖ https://www.youtube.com/watch?v=OvVl8rOEncE&t=127s
❖ https://www.youtube.com/watch?v=8Ji3g4yp4VE
 THE END
THANK YOU
* CHAPTER - 7
CONTROL AND
COORDINATION

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* 1a) 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.
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 * 2) Coordination in animals :-
In animals control and co ordination is done by the nervous system
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
information 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).
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 * HUMAN NERVOUS SYSTEM

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 * 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.

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 * CENTRAL NERVOUS SYSTEM

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 * PERIPHERAL NERVOUS SYSTEM

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* 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.

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* Structure of neuron (Nerve cell)

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* Transmission of messages through neurons

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 * The
c) Brain :-
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) Hind 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.
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 * HUMAN BRAIN

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 * 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.

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* 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.

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 * REFLEX ACTION

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* b) Reflex arc :-
The pathway of a reflex action is called reflex arc. In a
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 Sensory nerves
(Sense organ)
Spinal cord

Effectors Motor nerves

(Muscles/Glands)
Response
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 * REFLEX ARC

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* 5) Coordination in plants :-
In plants control and coordination is done by chemical
substances called plant hormones or phytohormones.
There are five main types of plant hormones. They are :-
Auxins, Gibberillins, Cytokinins, Abscisic acid and
Ethylene.
i) Auxins :- help in cell division, cell elongation and
growth.
ii) Gibberillins :- help in growth of stem and branches.
iii) Cytokinins:- help in cell division, formation of fruits and
seeds.
iv) Abscisic acid :- inhibits growth and affects wilting of
leaves.
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Ethylene :-- Allhelps in flowering and ripening of fruits.
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 *Movements
6) Movements intwo
in plants are of plants :- They are :-Tropic movements
main types.
and Nastic movements.
a) Tropic movements :- are directional movements towards or
away from the stimulus and it depends on growth. They are of
different types like Phototropism, Geotropism, Chemotropism,
Hydrotropism etc.
i) Phototropism :- is movement of plants in response to light. If it is
towards light, it is called positive phototropism. Eg:- Bending of
shoot towards light. If it is away from light, it is called negative
phototropism. Eg:- Bending of root away from light.
ii) Geotropism :- is the movement of plants in response to gravity. If it is
towards gravity it is called positive geotropism. Eg:- Downward
growth of roots. If it is away from gravity it is called negative
geotropism. Eg:- Upward growth of shoot.
iii) Chemotropism :- is movement of plant in response to chemical
stimuli. Eg:- Growth of pollen tube towards the ovule.
iv) Hydrotropism :- is the movement of plants in response to water.
Eg :- Growth of roots towards water.
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 PHOTOTROPISM GEOTROPISM

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 CHEMOTROPISM

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b) Nastic movements :- are non directional movements which
are neither towards or away from the stimulus and it does not
depend on growth.
Eg :- If we touch the leaves of touch me not plant, its leaves fold up
and droops down immediately due to the change in the amount of
water in the leaves. Depending upon the amount of water in the
leaves, it swells or shrinks.

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 *The7)endocrine
Endocrine glands
glands also in human
help in control beings
and coordination. The:-
endocrine
glands produce chemical substances which help to control and coordinate
various activities in the body.
The endocrine glands in our body are :- pineal, hypothalamus, pituitary,
thyroid, parathyroid, thymus, adrenal, pancreas, testes and ovary.
Examples of coordination by endocrine glands :-
i) When we are frightened or angry, the adrenal glands produce more
adrenalin hormone which is sent through the blood to the heart, rib muscles
and diaphragm. This increases breathing rate to supply more oxygen to the
muscles to prepare the body to either run away or fight with the enemy.
ii) Iodine is needed by the thyroid gland to produce the hormone thyroxin.
Thyroxin controls the metabolism of carbohydrates, fats and proteins and helps
in proper growth. If the diet is deficient in iodine it causes goitre.
iii) The pituitary gland produce growth hormones. Deficiency of this hormone in
childhood causes dwarfism. Excess of this hormone causes tall growth.
iv) The pancreas produces the hormone insulin which controls the blood sugar
level. Increase in blood sugar level causes diabetes. A diabetic patient has to
take insulin injections to control his blood sugar level.
v) The testes in males produces the hormone testosterone which controls the
production of sperms and changes during puberty.
The ovary in females produces the hormone oestrogen which controls the
production of eggs -and
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* ENDOCRINE GLANDS IN HUMAN
BEINGS

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* ENDOCRINE GLANDS IN HUMAN
BEINGS

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