presentation on control and coordination

8/3/2019 Presentation on Control and Coordination

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PRESENTATION ONCONTROL ANDCOORDINATION

Made by-

Kunal Tolani

X-E


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All the living organisms respond and react to changes inthe enviournment. The changes in the enviournment towhich the organisms respond and react are called

STIMULI. The living organisms show response to stimulisuch as light, heat, cold, sound, smell, etc. Theresponse of organisms to a stimuli is usually in the formof some movement of their body part. For eg, a mantouches a very hot utensil accidently, he quickly pulls his

hand away from the hard utensil. The reaction to stimuliis the characterstic property of the living organisms.. Theworking together of the various organisms in asystematic manner so as to produce a proper responseto the stimulus , is called COORDINATION


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CONTROL AND COORDINATION INPLANTSThe plants do not have nervous system and sense organs like eyes, ears

and nose etc. like animals, but they can still sense things. The stimulilike light, gravity, chemicals, water and touch are called environmentchanges. So plants co-ordinate their behaviour by using hormones.

The hormones in plants co-ordinate their behaviors by affecting thegrowth of a plant. And the effect on the growth of the plant can result inthe movement of a part of the plant like shoot (stem), or roots etc. Theplants responds to various stimuli very slowly by growing because plantshave no nervous system, so plants use only hormones for co-ordination.So in most of the cases, the response of a plant to the stimulus cannot

be observed immediately. It usually takes a considerable time toobserve the effect of a stimulus on a plant. The function of control andco-ordination in plants is performed by chemical substances calledPLANT HORMONES(PHYTO HORMONES).


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PLANT HORMONES(OR PHYTO

HORMONES)The control and co-ordination in plants is done by

plant hormones. The plant hormones are alsoknown as Plant Growth Substances. Thegrowth of a plant can be divided into three

stages: 1. cell division, 2. cell differentiation and3. cell enlargement.

These three stages of a plant growth as well aspromotion of dormancy, breaking of dormancy,

stomata control, falling of leaves, fruit growth,ripening of fruits and ageing in plants arecontrolled by various plant hormones.


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There are four major types of planthormones which are involved in controland co-ordination in plants. These are as

follows:

1. AUXINS:- These are the plant hormones

which promote cell enlargement and cell

differentiation in plants. They alsopromote fruit growth. Auxins hormonecontrols a plants response to light and

gravity. Auxins is made by the cells at thetip of the stems and roots. Auxins moveaway from light and towards gravity.

Auxins has opposite effect on the growth


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4.ABSCISIC ACID:- These are the plant

hormones which functions mainly as agrowth inhibitor. Abscisic acid promotesthe dormancy in the seed and buds (this is

the opposite of breaking of dormancy). Italso promotes the growth of stomata.Abscisic acid promotes the wilting and

falling of leaves (which is also calledabscission) it also causes the detachmentof flowers and fruits from the plants.


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1.TROPISMS(TROPIC MOVEMENT) A growth movement of a plant part in response

to an external stimulus in which the direction ofstimulus determines the direction of response iscalled TROPISM. Tropism is directional

movement of the part of a plant caused by itsgrowth.

The growth of a plant in response to stimuluscan be towards the stimulus or away from

stimulus due to which we can have a positivetropism or a negative tropism.


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CHEMOTROPISM


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3.CHEMOTROPISM:-the movement of aplant towards chemicals is calledchemotropism. If the plant moves towards

chemicals, it is called positive chemotropism,and if the plant moves away from thechemicals, it is called negativechemotropism.

4.HYDROTROPISM:-The movement of aplant in response to water is calledhydrotropism. If the plant moves towardswater, it is called positive hydrotropism, and if

the plant moves away from the water, it iscalled the negative hydrotropism.

THIGMOTROPISM:-The directional growthmovement of a plant in response to touch ofan organism is called thigmotropism.


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2.NASTIES(OR NASTIC MOVEMENTS)

The movement of a plant in response to anexternal stimulus in which the direction of plantmay or may not be towards the stimulus is

called theNASTIC MOVEMENTS(OR NASTIES)

.The direction of nastic movements is notdetermined by the direction of the stimulus isapplied. the folding up of the leaves of a

sensitive plant on touching is not a growthmovement but the opening and closing of petalsof flowers by the action of sunlight is growthmovement.


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COORDINATION IN ANIMALS

The multicelluar animals have specialized cellscalled the NERVE CELLS. A system made upof nerve cells is called the NERVOUS SYSTEM.

The control and coordination in higheranimals is called vertebrates takes placethrough nervous system as well as hormonalsystem called endocrine system. There a 5

sense organs in our body. The sense organscontain receptors. A receptor is a cell orgroup of cells in a sense organ which issensitive to particular type of stimulus such

as light, sound, smell, taste, heat, pressure,


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HUMAN NERVOUS SYSTEM

The function of the nervous system is tocoordinate the activities of our body. Thenervous system helps all other system of ourbody to work together. The nervous systemalso coordinates with the thing which wedont have to think about like heart beats andbreathing. The nervous system receives

information from the surroundings, process it,Interprets it and respond quickly.


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THE UNIT OF NERVOUS SYSTEM:

NEURON

The cell body of a neuron is like a typical animal cellwhich contains cytoplasm and a nucleus. Anumber of long and thin fibres are stretching outfrom the cell body of a neuron. They are callednerve fibres. The shorter fibres on the body of a

neuron are called dendrites. The longest fibres onthe cell body of a neuron is called axon. The axonhas an insulating and protective sheets(or cover)of myelin around it(myelin is made of fat andprotein).

The messages which the neurons transmit in thenervous system are in the form of electricalimpulses. The dendrites pick up the nerveimpulses from receptors.

Th th i l t th ll b d d th


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They pass the impulses to the cell body and thealong the axon. The axon passes the impulse toanother neuron through a junction called synapse.

Any two neurons in the nervous system do not join toone another completely. There is always a verysmall gap between the two neurons. The gap iscalled a synapse. The nerve impulses are carriedover this small gap between a pair of neurons by

means of a chemical substance calledneurotransmitter substances. This impulse travelsfrom the dendrite to the cell body, and then alongthe axon to its end. At the end of the axon , the

electrical impulse sets off the release of somechemicals. These chemicals cross the gap, orsynapse, and start a similar electrical


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Impulses in a dendrite of the next neuron. This is ageneral scheme of how nervous impulses travel inthe body.


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REFLEX ACTION AND REFLEX ARCS

The simplest form of response in the nervoussystem is REFLEX ACTIONS. This is a rapid,automatic response to a stimulus which is not aunder the voluntary control of the brain. A reflexaction is one which we perform automatically. Itis a comparatively simple form of behavior inwhich the same stimulus produces the same

response every time.Moving our hand away on touching a hot plate isan example of reflex actions.


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RELEX ARC

F l hi i fl ti


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For example, coughing is a reflex actionwhich clears our wind pipe. The pupil ofour eyes get smaller in bright light. This

reflex action protects the retina of our eyesfrom damage due to too much light. Thepupils of our eyes get bigger in dim light soas to help us see properly even in dim light

.The pathway taken by nerve impulses in a

reflex action is called the REFLEX ARC.

Reflex arcs allow rapid response. Nervesfrom all over the body meet in a bundle inthe spinal cord on their way to the brain.Reflex arcs are formed in this spinal cord

itself, although the information input also

b i R fl h l d i i l


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brain. Reflex arcs have evolved in animalsbecause the thinking process of the brainis not fast enough. Many animals have

very little or none of the complex neuronnetwork needed for the thinking. So it isquiet likely that reflects arcs have evolved

as efficient ways of functioning in theabsence of true thought process. Evenafter complex neuron networks have come

into existence, reflex arcs continue to bemore efficient for a quick responses.


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THE HUMAN BRAIN

BRAIN is the highest coordinating centre in the body.The brain is located inside the skull of our body. It isprotected by a bony box in the skull called CRANIUM.The brain is broadly divided into three regions whichare as follows:

1.FOREBRAIN:-It consists mainly of cerebrum, which isthe main thinking part of the brain. It is the site of ourfaculties such as learning, reasoning, intelligence,personality and memory. All our thoughts, sensation,

action, and movements are controlled by thecerebrum. All the voluntary actions of the body arecoordinated by the cerebrum.


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2 MIDBRAIN: It does not have the further


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2.MIDBRAIN:-It does not have the furtherdivisions. It controls reflex movements of thehead, neck and trunk in response to visualand auditory stimuli and also controls the

reflex movements of eyes, muscles, changein pupil size and shape of the eye lens.

3.HINDBRAIN:-IT consist of three centers calledthe pons, cerebellum and medulla. Pons take

part in regulating respiration. Cerebellumhelps in maintaining the posture and balanceof the body and also enables to make preciseand accurate movements . It coordinates

smooth movements such as walking,bending, dancing etc. Medulla controlsinvoluntary actions such as heart beat,breathing etc.


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HORMONES IN ANIMALS

Hormones are chemical substances secretedin very small amounts by specialized tissuein the body called endocrine glands. Thesehormones coordinate the activities of livingorganisms and their growth. Hormones aremade inside the body of an organisms invery small amounts.

They are of the following types:-1.Pituary glands.:-it is situated in the brain.

Hormone secreted is the growth hormone


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2.Pineal glands:-located in the brain. Hormone secretedis the melatonin.

3.Thyroid glands:- located in the neck region. Hormone

secreted is the thyroxine.4.Parathyroid glands:- located just behind the thyroidglands. Hormone secreted is the parthorme.

5.Thynus glands:-located near the heart. Hormonesecreted is thyroxine.

6.Pancreas:- located below the stomach. Hormonesecreted is insulin.

7.Adernal glands:- located above the kidneys. Hormonesecreted is aderlaine.

8. Testes:-found only in male. Hormone secreted istestostrene.

9.ovary:- located in females. Hormone secreted isoestrogen.

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