Useful for students of SSC, ICSE, CBSE - Std. 10th, 8th

1. Standard 10 The Regulators of Life
Gurudatta K Wagh

2. Control Systematic regulation of various activities
Co-ordination Orderly execution of the activities
Co-ordination is necessary between organs and
organ systems that bring about all the inter-related life
processes
Homoeostasis Maintenance of the steady state by
different systems of an organism for its optimal
functioning because of perfect co-ordination

3. Co-ordination in plants
Plants do not have a nervous system or muscular
system
The movements exhibited by plants are mainly in
response to the stimulus
A seedling and its movement
•The movement of a seedling is because of growth
•If growth is prevented, it (seedling) does not exhibit
any movement

4. Seismonastic movement (stimulus of touch) Mimosa

6. When tendrils come in contact with any object, the
portion of the tendril which is in contact with the
object grows slowly and the other portion grows fast
and entwines around the object
Tendrils are sensitive to touch

7. Plants exhibit two types of movements, 1) growth
dependent, and 2) growth independent
1) Growth Dependent Movement
Tropism or tropic movement The movement or
growth of any part of a plant in response to an
external stimulus
Phototropic movement (Phototropism) The
shoot of any plant grows in the direction of source
of light When a potted plant is kept near the window
in a room the stem bends slightly towards the
window

8. Shoot When light falls on a part of the plant, a
hormone called auxin which is synthesized at the tip
of the shoot helps the cells to grow longer

9. As the light is falling on one side of the plant, the
hormone auxin diffuses towards the side of the shoot
which is not in sunlight and stimulates the cells to
grow longer
Hence the plant appears to bend towards light

10. Gravitropic and hydrotropic movements
Root The root system of the plants responds to the
stimulus of gravity and water

11. The growth of pollen
tubes towards the
ovules in response
to certain chemicals
Chemotropic movement (Chemotropism)

12. Examples of plant hormones
Auxins, Gibberellins - growth of the stem
Cytokinins - promote cell division; fruits, seeds
Abscissic acid - inhibits growth and leads to wilting of
leaves

13. 2) Growth Independent Movement
Hormones bring about various movements in plants
in response to the changes occurring in the
surroundings
Plants use electrochemical means to transfer
information from one cell to another as there is no
specialized tissue present for the conduction of
information
Movement is also brought about as the plant cells
change their shapes by altering the amount of water
in them. The cells either swell or shrink and thus
change their shapes

14. •The Venus flytrap has a trap which looks and smells
like a flower to insects. When insects land on it, they
touch a trigger hair which slams the trap shut and
they are then digested by the plant
•Lotus opens in the morning and the tuberose at
night

15. •The tentacles on the leaves of the insectivorous
plants like drosera curl inwards at the touch of an
insect and trap the insect

16. •The explosive fruit of
balsam plant bursts open
at an appropriate time and
scatters the seeds

17. Co-ordination in human beings
In human beings the co-ordination of different bodily
activities are controlled by (1) nervous control and (2)
chemical control. The components of the human
nervous system are the brain, spinal cord and the
nerves.
11.3.1 The human nervous system The nervous
system can be divided into (i) the central nervous
system (CNS), (ii) the peripheral nervous system
(PNS) and (iii) the autonomic nervous system (ANS)

18. (i) Central nervous system (CNS) Comprises of the
brain and the spinal cord and regulates all activities
of the body
(ii) Peripheral nervous system (PNS) Includes all
the nerves. The nerves form a network and spread
throughout the body and connect all parts of the body
to the CNS
(iii) Autonomic nervous system (ANS) Comprises
of all the nerves present in the involuntary organs like
heart, stomach, lungs, etc.

19. Nerves
(i) Afferent nerves carry impulses from the sensory
organs to the brain
(ii) Efferent nerves carry impulses from the brain to
the sensory organs
Structure The nerves are composed of neurons and
neuroglia. The neurons are specialized cells capable
of creating and transmitting electrochemical impulses.
The neuroglia are supportive cells which assist the
neurons in their function

20. Specialized tips of dendrites of a neuron pick up the
information from our environment. It sets off a
chemical reaction producing an electrical impulse
which travels from the dendrite to the cell body and
from there, through the axon (nerve fibre) to its end

21. Journey of an impulse

22. At the end of the first axon, the electrical impulse
induces the release of some chemicals
These chemicals go across the small gap (synapse)
of 2- 20 nanometre (nm) between the neurons and
start a similar electrical impulse in the dendrite of the
next neuron
This is the procedure by means of which the
impulses travel in the body from the neurons and are
delivered to the muscle cells or glands

23. Journey of an impulse

24. The movement at the cellular level takes place when
the cells change their shape, so that they shorten.
Muscle cells possess special kinds of proteins which
are capable of bringing about change in their shape
and make the cell capable to respond to the nervous
electrical impulses.
Muscle tissue When an
action or movement has to
be brought about, the
muscle tissue does the final
job. The muscle cells
should move to enable
work to be done.

25. Nervous tissue is composed of a highly organized
network of neurons capable of transferring
information in the form of electrical impulses from
one part of the body to another
Classification of neurons
Sensory neurons conduct impulses from the sense
organs to the brain and spinal cord
Motor neurons conduct impulses from the brain and
spinal cord to the effector organs like muscles
and glands
Association (Interneuron) neurons perform
integrative functions of the nervous system

27. Types of neurons

28. For information
In unicellular amoeba there
is no nervous system
The nervous system in hydra
is at a very primitive stage

29. For information
A number of nerve cells come together
and form a cluster in earthworm
These clusters are joined together to
form a beaded structure called the nerve
cord
Taste buds at the tip of the tongue
detect sweet taste, those at the back
– bitter taste, side – salty and sour

30. When we inhale smell enters the back of the nose . When
we have a cold, food tastes odd because nasal organs get
inflamed
Each side of our brain controls the opposite side of our
body. Left – speaking, writing, logical thought. Right –
artistic abilities
Sensory memory is weak
Short term memory lasts for 30 seconds
Long term memory retains things carefully learned and
memorized
Hormones (chemical messengers) are secreted by
endocrine glands (glands of internal secretion)

33. Reflex Action Any sudden action in response to
some happening in the environment
Nerves from all over the body meeting in a bundle is
commonly called as the spinal cord. Reflex arcs are
formed in the spinal cord.
In lower animals the complex neuron network
needed for thinking is not there or is not well
developed. Hence reflex arcs have been evolved as
efficient ways of functioning in the absence of the
true thought processes.
In spite of the presence of complex neuron
networks, reflex arcs continue to be more efficient
for quick responses

35. The Central Nervous System (CNS)
•It is a delicate structure composed of the brain and
the spinal cord
•The brain is protected by a bony structure called the
cranium or skull and the spinal cord by the vertebral
column or the back bone
•Protective membranes called the meninges are
present in the space between the soft CNS and the
bone

37. •The ventricles, central canal and the space between
the meninges are filled with cerebrospinal fluid (CSF)
•CSF keeps the CNS well nourished and also
protects it by absorbing mechanical shocks.
•There are cavities present
on the different parts of the
brain known as ventricles
while the long cavity of the
spinal cord is called the
central canal

38. Many of our actions are voluntary in nature e.g.
walking, clapping, bending, etc. In all these actions
there is involvement of our muscles
The brain sends message to the muscles and the
muscles act accordingly. This is the second instance
where the nervous system is communicating with the
muscles
Such a communication between the central nervous
system and the other parts of the body is brought
about by the Peripheral Nervous System (PNS)
which is composed of cranial nerves arising from the
brain and the spinal nerves arising from the spinal
cord. The brain makes us think and we act based on
our thinking

39. CNS and PNS

40. The brain is a complex organ divided mainly into three regions:
1) forebrain, 2) midbrain, 3) hindbrain
Forebrain (cerebrum) Main thinking part of the brain. It has
regions which receive the sensory impulses from various
receptors
Association centres The areas for smell, hearing, vision, etc.
are separate. There are different areas where the sensory
information received and interpreted are put together with the
information received from other receptors as well as the
information that is already stored in the brain. Such centres are
known as association centres. On this basis a decision is
taken on how to respond and the information is sent to the
motor areas which control the movement of the voluntary
muscles

41. Forebrain, midbrain, hindbrain

42. Midbrain and hindbrain
Involuntary actions are
controlled by the midbrain
and hindbrain
Blood flow, breathing, sneezing, etc. are controlled
by the medulla oblongata, a component of the
hindbrain
Another component of the hind brain is cerebellum.
It is responsible for coordinating the voluntary
movements and also maintaining the balance of our
body e.g. riding a bicycle, picking up an object from
the floor, running along a straight line, etc.

43. The chemical control
Hormones are secreted by the endocrine glands (ductless
glands). These glands do not have any duct to transport their
secretions. On production these hormones are directly
released into the blood stream. Due to this, the hormones
reach everywhere in the body, though the glands secreting
them are located in particular places
Endocrine and nervous systems
Both the systems work in co-operation to integrate and control
various body activities
The significant difference between the two systems is that the
nerve impulses (nervous system) are rapid and are usually of
short duration while the hormonal action (endocrine system) is
much slower and long lasting

44. It is very
important that
hormones
should be
secreted
according to
the
requirement
When the sugar level of blood rises, it is detected by
the cells of the pancreas which respond to the
situation by producing more insulin. As the sugar level
of the blood falls, the secretion of insulin is reduced

45. THANK YOU
SSC Std 10th Textbook
CBSE Std 10th Textbook
YouTube
Google
Wikipedia
Suggestions and Appreciations welcome
gkwagh@gmail.com