Notes of Control and Coordination

CHAPTER 7 – CONTROL & COORDINATION

KEY CONCEPTS & GIST OF THE LESSON

˜  Coordination-The working together of various organs of the body of an organism in a proper

      manner to produce appropriate reaction to a stimulus is called coordination.

  Example : Withdrawal 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

Parts of the Nervous system – (i) Brain (ii) Spinal cord (iii) Nerves (Neurons)

Functions

(i) To receive the information from environment

(ii) To receive the information from various body parts.

     (Stimuli ® Response)

(iii) To act accordingly through muscles and glands.

Stimulus : Any change in environment to which the organisms respond and react is called stimulus. E.g., touching a hot plate.

Response : The reaction of our body to a stimulus. E.g. withdrawal of our hand on touching hot plate.

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 present in  Sense Organs

Photo receptors  Thermo/Thigmo        Phono                  Olfactory             Gustatory

                               receptors              Receptors               Receptors            Receptors

      Eyes                   (Skin)                   Ear                       (Nose)                (Tongue)

   Visual                    Pain                  Hearing/Balance        Smell              Taste Detection

    Stimulus               Touch                of the body               Detection

                                   Heat                      

Neuron : It is the structural and functional unit of nervous system.

Neuron has 3 main parts:

1.      Dendrite    : Information is acquired.                  

2.      Cell body   : Information travels as an electrical impulse.                   

3.       Axon         : Information travels as an electrical impulse.                   

Synapse : Part where electrical signal is converted into chemical message for onward        

                 transmission to next neuron by release of neurotransmitters.

Synapse :  Space/junction between two adjacent nerves (between the terminal branches of axon of one neuron with the dendrite of another neuron) is called Synapse.

v Passing of information takes place – (i) By Electric impulse (inside the neuron) and

                                                                   (ii) In the form of chemicals (At synapse)

v Nervous system

Stimulus → Receptor organ → Sensory nerve → Brain/Spinal cord

                                                                                     ↓

                       Response ← Effector organ ← Motor nerve

v Endocrine system

   Stimulus → Endocrine organ → Secrete hormone → Hormone in blood

                                                                                               ↓

                                                             Response ← Target organ

REFLEX ACTION

Reflex action is quick, sudden and immediate response of the body to a stimulus.

- Spontaneous, involuntary and automatic response to a stimulus to protect us from harmful situations.

 Eg. On touching a hot object unknowingly we instantly withdraw our hand, knee jerk etc.

Reflex arc : The pathway through which nerve impulses pass during reflex action is called reflex arc.

Stimulus → Receptor organ → Sensory nerve → Spinal cord →Motor nerve →Effector organ→ Response

Response

Responses are of three main types

1.      Voluntary : Controlled by fore brain

           eg. Talking, Writing

2.      Involuntary : Controlled by mid and hind brain

          eg. Heart beat, vomiting, regulation of heartbeat

3.      Reflex action : Controlled by spinal cord

           eg. Withdrawl of hand on touching a hot object.

v Nervous system- (1) Central Nervous system (CNS) –i) Brain

                                                                                             ii) Spinal cord

                           (2) Peripheral Nervous system(PNS)- i) Cranial nerves-arise from brain.

                                                                                ii) Spinal nerves-arise from spinal cord

                              (3) Autonomic Nervous system

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.. Receives sensory impulses from various body parts and integrates it.

Cerebrum has 3 main areas.

a. Sensory area- to receive impulses from sense organs via Receptors

b. Motor area- control voluntary movements.

c. Association areas- Reasoning, learning & intelligence.

HYPOTHALAMUS :

   Connecting link between nervous system and Endocrine system.

   Controls body temperature.

   Centre assosciated with hunger.

PITUITARY GLAND : Secretes hormones. (Master Gland)

Mid Brain : Connects forebrain to hind brain.

Hind Brain :

CEREBELLUM

i) Controls posture and balance

ii) Control precision of voluntary actions

Walking in a straight line.

MEDULLA: Controls involuntary actions

eg. blood pressure, salivation, vomiting

PONS:  Involuntary action, regulation of respiration

PROTECTION OF BRAIN AND SPINAL CORD

˜ Brain : i) Brain is also enclosed by three membranes i.e. Meninges.

   ii) Cerebrospinal fluid is present in between the three meninges. It acts as shock absorber.

   iii) Brain is enclosed in cranium (Brain Box).

˜ Spinal Cord : Spinal Cord is enclosed in Vertebral column.

Coordination between Nervous and Muscular Tissue

Motor nerve  ← Brain/ Spinal cord← Sensory nerve←Receptors← Stimulus

         ↓

Nerve impulse → Muscle cell → Change in arrangement of proteins in muscles

                          (Effector organ)                                               ↓

Action caused ← Shorter form of muscles ← Change in shape of muscle

Need for Endocrine System/ Chemical communication

v Chemical communication by hormones is needed because of limitations of electrical

         communication:

(i) Electrical impulses have their limitations because they reach only those cells connected

      to the nervous tissue.

(ii) Also the nerve cells cannot generate & transmit impulses continuously. They need resting  

        time.

 Chemical communication also has a disadvantage : It is slower communication as compared to 

    electrical communication.

ENDOCRINE SYSTEM IN ANIMALS

Endocrine System helps in control and coordination through chemical compounds called HORMONES

˜ Hormones : These are the chemical messengers secreted by endocrine glands, in very small amounts, into the blood stream. They act on target tissues/organs usually away from their source.

They do not take part in the reaction & are destroyed immediately.

v Hormones are secreted by- Endocrine glands

S. No.      Endocrine glands                      Exocrine glands

1.      Ducts absent                                         Ducts present

2.      Secrete hormones                                Secrete enzymes

3.     Secreted in blood                                 Secreted in ducts of glands

4. Situated away from the site of action      Situated near the site of action

v Some glands which act as both endocrine & exocrine

Gland                            Endocrine function                             Exocrine function

Pancreas             Produces insulin & Glucagon hormone        Produces digestive enzyme.                                  

                                         .                                                          (pancreatic amylase)

Testes                 Produces hormone Testosterone                   Produces male gametes

Ovaries               Produces hormone Oestrogen                       Produces female gametes                    

                                                                                                   (reproductive cells)

v Important Endocrine glands, the hormone they secrete & their function

                Refer to figure 7.7 page no. 124 of N.C.E.R.T Text book)

Endocrine gland        Hormone                                   Function

1. Pituitary gland      Growth hormone      Body growth, development of bones & muscles

                                                                                    (If excess- Gigantism)

                                                                                     (If less- Dwarfism)

2.Thyroid gland            Thyroxine             Regulates carbohydrate, protein & fat metabolism

                                                                                    ( If less- Goitre)

3.Pancreas                    Insulin and              Regulates blood sugar levels

                               Glucagon hormone               (if less diabetes is caused) 

 4.Testes                      Testosterone          Development of secondary male characters like

   in males                                                        deep voice, beard, etc.

5.Ovaries in                 Oestrogen           Development of secondary female characters like

   Females                                                mammary glands, menstrual cycle, maintenance

                                                                    of pregnancy.

6. Adrenal gland        Adrenaline         Regulation (increasing) blood pressure, heart beat, 

                                                                   carbohydrate metabolism (during emergency)

7. Pineal gland           Melatonin                           Biological Clock

8.  Thymus                 Thymosin                       Immunity of body

9. Parathyroid            Parathyroid                 Maintains calcium level in blood

       Gland                   hormone

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 cause disease called goiter.

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 ® which helps in regulating blood-sugar level.

Feedback Mechanism

The excess or deficiency of hormones has a harmful effect on our body.

Feedback mechanism makes sure that hormones should be secreted in

precise quantities and at right time.

                             Coordination in Plants

Ø  Plants also show movement in response to stimulus, So they also need coordination in different parts . In plants only chemical coordination is possible as they don’t have nervous tissue.

Movement in Plants

Two types of movements are shown by plants:

1.      Tropic movements                                                 2.  Nastic Movements

    Movement dependent                                                   Movement independent

      on growth                                                                            of growth

      (slow response)                                                              [immediate response                                                                                                           

                                                                                                to stimulus]

                                                                                       eg. dropping of leaves

                                                                                             of Touch-me-not

                                                                                            plant on touching it

                                                                                               (Thigmonasty)

Tropic movements [growth dependent directional movements in response to stimulus]

These may be in direction of stimulus (+ve tropism) or away from stimulus (-ve tropism)

Phototropism                    Geotropism           Chemotropism                  Hydrotropism

Movement                        Movement                 Movement                    Movement

towards light                   towards gravity       towards Chemicals         towards water

( +ve in shoot)                ( +ve in roots)           (growth of pollen           (+ve in roots)

(-ve in root)                     (-ve in shoot)           tube towards ovule)

Refer to figure 7.4 & 7.5 page no. 121 of N.C.E.R.T Text book)

Ø  Movements in plants is not due to contraction of muscles as they donot have muscular tissue. But in plants, cells change their shape by either gaining water (swelling of cell) or losing water (shrinking) thus making plant movements possible.

Plant Hormones (Phytohormones)

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 shady/ darker side.

 (b) Gibberellin : Helps in the growth of the stem

(c) Cytokinins : Promotes cell division

(d) Abscisic acid : Inhibits growth, cause wilting (falling) of leaves. (Stress hormone)

 e) Ethylene: Fruit ripening.

v Important diagrams-

1. Structure of neuron (nerve cell)   2. Reflex arc   3.Human brain    4.Endocrine glands .

v Important activities-

1. To compare taste of sugar and food with open & blocked nostrils.

2. To demonstrate the response of a plant to the direction of light.

3. To demonstrate hydrotropism.