Control and Coordination

Amit Sharma
PGT Biology
MTC School
Bhattu Mandi

Need Of Control And
Coordination In Animals:
Organism is in direct
contact with its environment,
so any changes in its
surroundings have an influence
on its body.
To maintain the balance
between the environmental
factors and body functions
there is a need of such
controlling and coordinating
system that works for the
welfare of the organism.

NERVOUS SYSTEM:
In animals this control and coordination
is carried out by Nervous and muscular
system. Human nervous system consists of
two parts:
 Central nervous system:
It consists of Brain and Spinal Cord.
 Peripheral Nervous System:
It consists of cranial and Spinal nerves. 12
pairs of cranial nerves and 30 pairs of spinal
nerves.

CENTRAL NERVOUS
SYSTEM:
It is the main part
of the Nervous system
consisting of two main
Organs:
Brain and Spinal cord.
These parts are
the main centre for
receiving, interpreting
and generating response
for any stimulus.

BRAIN
It is the most complex organ in the human body. It
is divided into three main parts:
1. Forebrain,
2. Midbrain
3. Hindbrain.
It is the centre of performing all type of actions
either voluntary (actions that are controlled by
organism) or involuntary in nature (actions that are
not controlled by organism).
It perform the functions same as that of a central
processing unit (CPU) in computer.

FORE BRAIN
It is the front and largest part of the brain. It
consists of Olfactory lobes, diencephalon and Cerebrum.
FUNCTIONS:
 It is the main thinking part of the brain.
 It has separate area for receiving sensory impulses
 It also transmits motor impulses to the muscles to
show response.
 It has centre for hearing, hunger, smell, sight,
intelligence, memory, learning, vision, mood and
emotions.
 Hypothalamus and pituitary glands secretes variety
of Hormones.

HIND BRAIN
It is the back part of brain and consists of
medulla, pons varoli and cerebellum.
FUNCTIONS:
 It controls the involuntary actions along with
mid brain.
 Blood pressure, Heart beat, sneezing,
salivation and vomiting are controlled by
medulla.
 Cerebellum is responsible for equilibrium,
precision of voluntary actions, maintaining
posture and balance of the body.

Our central nervous
system is properly
protected to prevent any
injury.
 Brain is placed inside a
bony box known as
Cranium, Inside which
the brain is surrounded
by a fluid to protect
from shock.
 Spinal cord is also placed
in the vertebral column.
Protective Structures Of Brain:

NERVE CELL:
It is the longest cell found in human body
may reach up to a length of 1 meter.
 Nerve cell is divided into three parts i.e. Cell
body, Dendrites and Axon.
 Cell body is rounded part having a nucleus and
other cell organelles. Cell body bears short
thread like structure known as dendrites which
receives the stimulus.
 Axon is a long process which carries information
to one neuron to another neuron.
 A very small gap is present in between two
neurons, this gap is known as Synapse.

Functioning:
 The stimulus is received by the dendritic tips of a nerve cell and carried
in form of an electrical impulse.
 Impulse travels from dendrites to cell body and then through the axon
at its end.
 Here it set up a chemical impulse by releasing some chemicals known
as Neurotransmitters in the synapse.
 These chemicals pass through the synapse and reach to dendrites of
other neuron to transfer the information again in electrical form.
 When synapse occurs between a neuron and muscle cell then it is
known as Neuromuscular Junction.
 Acetylcholine is the neurotransmitter present in the synapse.

Reflex Action:
It is a nerve mediated spontaneous, automatic
involuntary response to a stimulus without the will
of the organism. It is discovered by Marshall Hall
in 1833.
Example:-
If we accidentally touch a hot plate our hand
moves backward instantly without thinking of the
matter happening.
It occurs by the involvement of Spinal cord so
it happens very quickly as the receptors and
effectors are in direct contact with each other in
spinal cord.

Reflex Arc:
It is the path followed by the reflex action to
show a response.
Receptors  Sensory Nerves  Spinal Cord  Motor Nerves  Effectors

Action Of Nervous Tissue:
Conduction of nerve impulse from sensory
receptors to brain and then to effectors to show
the response is carried out by nerves. But actually
the response is shown by the muscles or gland
cells.
Muscles cells are able to change their shape
because of the presence of some contractile
proteins which results in movement of muscles.
Myosin and Actin are the proteins which unable
the muscle to move.

Coordination In Plants
Plants respond to stimulus by two ways either by
growth movements such as changes shown by growing
plants or by some chemical changes such 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.

Growth Movement
In some plants
movements occurs by
growth such as increase in
size, in tendrils which are
sensitive to touch.
Tendril when comes in
contact with some object
the part which is away
grow rapidly and coils
around the object.
Bending of plant stem
towards the light is also a
growth movement. These
movements are slow.

On the basis of stimulus the movements are of
various types:
 Phototropism:
light is stimulus and plants move towards or away
from the light. Stem is positively phototropic.
 Geotropism:
gravity is stimulus and plants move towards or
away from the light. Root is positively geotropic.
 Hydrotropism:
water is stimulus and plants move towards or away
from the light. Root is positively hydrotropic.
 Chemotropism:
chemical is stimulus. Pollen tube shows
chemotropism while entering the ovule.

Chemical Coordination
The nervous system show insufficiency as it does not
associated with each 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 be detected by
other cell even transmitted 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.

Plant Hormones
 Auxins:
it helps in elongation of cells.
 Cytokinins:
it promotes cell division.
 Gibberellins:
it helps in growth of plant in length.
 Abscisic Acid:
it inhibits growth and it also induces Dormancy
(period in which no growth occurs during unfavorable
conditions)

Animal Hormones
These are secreted by endocrine
glands:
 Hypothalamus:
situated in brain it releases some
factors which control the
secretions of pituitary gland.
 Pitutary 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.
 Pineal:
situated in brain. Secrete
melatonin hormone which regulate
the body color in animals.

 Parathyroid:
secrete Parathormone which along with Calcitonin control calcium
level in blood plasma.
 Thyroid:
it secretes Thyroxin which controls the metabolism of carbohydrates,
fats and proteins. It also secretes Calcitonin which along with
Parathormone control calcium level in blood plasma.
 Pancreas:
it secrete Insulin hormone which control blood sugar level.
 Adrenal:
it secrete Adrenalin hormone which regulates heart beat to maintain
proper oxygen supply in emergency condition. It is situated over
Kidneys, one on each kidney.
 Gonads:
in male, gonad (testes) secrete Testosterone and in female gonads
(Ovaries) secrete Oestrogen which control sex organs and sexual
characteristics during puberty.

Control and Coordination

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