CHAPTER 7

Control and Coordination

Control and CoordinationThe Nervous System

In animals Nervous system & Hormonal system plays an important role in control & co-ordination.

In plants control and coordination is done by chemical substances called plant hormones or phytohormones.

Coordination in animals :- In animals control and co ordination is done by the nervous system and endocrine system. Nervous system- The nervous system is an organ system containing a network of specialized cells called neurons.Types of Nervous system-1.Central Nervous system(CNS) – It includes – Brain & Spinal cord.2.Peripheral Nervous system( PNS)- It includes

a. Somatic nervous system(SNS)- it is also known as voluntary nervous system & associated with the voluntary control of body movements via skeletal muscles.

It includes – Cranial Nerves & Spinal nervesCranial nerves- 12 pairs arises from brain Spinal nerves- 31 pairs arises from spinal cord.b. Autonomic nervous system(ANS)- it is also known as

involuntary nervous system in which sensory & motor neurons plays an important role.

It is sub divided into –i) Sympathetic nervous system ( for fight,flight) &

ii)Parasympathetic nervous system ( for rest,digest).

• Neurons(Nerves)- The structural & functional unit of Nervous system called as Neurons.

Structure of Neurons- 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 may covered by Schwann cells & a protective covering called Myelin sheath.*Schwann cells separated by a gap called as Nodes of Ranvier.*Neuron ends by bulb like structure at nerve ending called as Synaptic Knob.*Synaptic knob consists of several vesicles called as Synaptic vesicles, which contain the chemical for pass on the information, called as Neurotransmitters. Ex. Acetyl choline.

Synapse-The junction between two neurons or with muscles is called synapse.

• Nerve impulse -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.

Reflex actionReflex action is a sudden, unconcious and involuntary response of the effectors to a stimulus. Ex :- 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.

• 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.

THE BRAIN PLAYS NO ACTION AS THE REFLEX ACTION TAKES PLACE AT THE LEVEL OF SPINAL CORD.

BUT LATER BRAIN IS INFORMED BY THE SPINAL CORD AND THEN LATER THE THINKING PART OF THE ACTION IS DONE BY BRAIN.

BUT BRAIN IS NOT ACTIVE DURING A REFLEX ACTION.

Difference between Reflex action & walking.

• Reflex action1. It is inborn, involuntary

( automatic) & require for survival & protection.

• Walking-1.It is acquire by learning,

under control of brain(voluntary) & for various function

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 Thalamus. 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.

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.

• Muscles are 3 types-• 1.Skeletal muscles ( Voluntary muscles /Striated

muscles)- attached with bones & having alternate dark and light bands

• 2.Smooth muscles ( Involuntary muscles .Non striated muscles) present in internal body organs.

• 3.Cardiac muscles- present in heart

Nerve impulse reaches to muscle which resulted into muscular action.

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,seed germination etc.

iii) Cytokinins:- help in cell division, formation of fruits and seeds.

iv) Abscisic acid :- inhibits growth and affects wilting of leaves.

vi) Ethylene :- helps in flowering and ripening of fruits.

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 :- 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.

PHOTOTROPISM GEOTROPISM

CHEMOTROPISM

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.

ENDOCRINE GLANDS IN HUMAN BEINGS

Endocrine glands in human beings :- The endocrine glands are also known as Ductless gland.

The endocrine glands produce chemical substances called as Hormones, & it directly diffuses into blood and reaches to target organ.

The endocrine glands in our body are :- pineal, hypothalamus, pituitary, thyroid, parathyroid, thymus, pancreas, adrenal, testes and ovary.

• Hypothalamus gland –it forms various releasing or inhibiting hormones & regulate the Pituitory glands for further function.

for ex. GH-RH/IH, T-RH, Gn-RH/IH, C-RH, OT,ADH etc.• Pituitory gland- It function in response of hypothalamus & releases hormones. For ex. *GH-Growth hormones – It help for body growth. Deficiency of GH- causes Dwarfism & its excess secretion cause Gigantism

*TSH- Thyroid stimulating hormone-Stimulate thyroid gland to form the thyroxine hormone

*Gonadotropin hormones- FSH &LH /ICSH(FSH-Follicle stimulating hormone, LH-Luteinising hormone/ ICSH(Interstistal cells stimulating hormone)-stimulates gonads like ovary./testis.

FSH- it stimulates testes/ovary to form sperms/ova as well as stimulate these gonads to secretes the sex hormones (Testosteron in male / Estrogen in female.)

LH (in female)/ICSH(Interstistal cells stimulating hormone in male)- ICSH help to stimulates the testis to form the Testosterone hormones & LH – stimulates corpus luteum to secrete progesterone hormone which plays important role in ovulation.

* Prolactin ( LTH- luteo tropic hormone)- It is required for the development of mammary glands.

*ACTH- Adreno cortico-tropic hormone-stimulates Adrenal gland ( Adrenal cortex – it forms hormones like Gluco-corticoids, Mineralo-corticoids, Androgens.)

* Oxytocin- It is also known as Birth hormone & milk ejection hormone

* Vasopressin (ADH-Anti-diuretic hormone)- Help in reabsorption of water . Its deficiency cause Diabetes insipidus.

Thyroid glands- a pair of glands present in neck region,

which forms throxine hormone in response of TSH of

pituitory.

Thyroxin hormone - Thyroxin controls the metabolism of

carbohydrates, fats and proteins and helps in proper

growth. If the diet is deficient in iodine it causes deficiency

of thyroxin leads to cause the goiter in which enlargement

of thyroid glands cause the swelling of neck. The goiter

disease are generally found in people living in northen

sub-himalayan areas where the diet are deficient of iodine.

Hence one must take the iodised salt.

Excess secretion of thyroxin cause exophthalmia

(protrusion of eyes)

Parathyroid glands- two pair of parathyroid glands which

are close to thyorid gland. It secretes the parathormone

which require to control the Calicium and phosphourous.

It deficiency cause Cramps and spasms

Thymus gland- It is present near the heart & secretes the

hormone Thymosine. It is required for maturation of T-

lymphocytes which require for immunity.

Adrenal glands – a pair of glands present over

the Kidney, Adreneal gland having two parts-

Outer Adrenal cortex & inner medulla.

Adrenal cortex - stimulated by ACTH & forms

3 hormones namely - Gluco-corticoids, Mineralo-

corticoids, Androgens. . It requires for Glucose

metabolism, mineral balance, secondary sexual

characters respectively.

Adrenal medulla- it prodiuces two

hormones – Adrenaline &

Nor adrenaline

Adrenaline hormone – It is also known

as Emergncy hormone or hormone of 3 F

– Fight,Flight,Freight.

It increase of heart beats,

blood pressure, rate of breathing , causes

rapid contraction of rib muscles etc to

full fill the increasing demand of body.

Nor adrenaline hormone- It require for

normal functioning of heart beat,blood

pressure,breathing rate etc.

Pancreas- It is heterocrine gland

( Exocrine & Endocrine gland) The

endocrine part of pancreas known as ilets

of langerhans.

It has two types of cells- Beta cells &

alpha cells, which forms hormones- Insulin

& glucagon respectively.

Insulin- Beta cell secretes the Insulin

hormone which controls the blood

sugar .The excess of blood sugar

converted into glycogen and stored into

liver.

The deficiency of insulin hormone

causes the disease, Diabetes mellitus.

Glucagon- Alpha cells secretes the

glucagon hormone which convert

glycogen into glucose during starvation.

v) Testes- In male a pair of

testes present which act as

heterocrine glands. It stimulated

by FSH & ICSH of pituitory

gland.

In response ICSH( Interstial cell

stimulating hormone) stimulates

the leydig cells/Interstial cells ,

which result to produce the

Testosterone , it is require for

development of secondary

sexual characters ,masculine

characters .

It also plays an important role in

spermatogenesis

• Ovary – In female a pair of ovaries present.

• In response of FSH the maturation of ova takes place

• These maturing ova forms the hormone –Estrogen. It is required for development of secondary sexual characters.

• LH- hormones of pituitory gland stimulates Corpus luteum ,which form the hormone Progesterone.

• Progesterone hormone help to maintain the pregnancy, hence it is also known as Pregnancy hormone.

-Prepared by R.S.Chandanshiv,Principal,

JNV,Haflong,Distt.Dima Hasao (Assam)

Contact- ravi_chandanshiv@yahoo.com