PITE Services: Control and Coordination

CONTROL AND COORDINATION

Basic Terms

STIMULUS:- The change in the environment, to which the organisms respond and react are called stimulus.

CO-ORDINATION:- The working together of various organs of the body of an organism in a proper manner to produce proper reaction to a stimulus, is called co-ordination.

NERVOUS SYSTEM: It is the system of conducting tissues that receives the conducting tissues that receives the stimulus and transmits it to other parts of the body forming a network.

VERTEBRATE NERVOUS SYSTEM CONSISTS OF TWO PARTS:

1. Central Nervous system (CNS) (including brain and spinal cord).

2. Peripheral Nervous System (PNS) (including cranial, spinal, and visceral nerves).

1 It regulates involuntary actions.

2 It controls and coordinates voluntary muscular activities.

3 It enables us to think, reason and remember.

NEURON

Neuron is the structural and functional unit of nervous system. It has a special structure but varies greatly in size and shape neurons are in fact, the largest cells present in the human body.

A NEURON CONSISTS OF THREE PARTS

CELL BODY:-The cell body of a neuron is also called cyton or soma. It contains a central nucleus and cytoplasm. It also contains group of ribosomes and endoplasmic reticulum cell body is concerned with metabolic maintenance and growth.

DENDRITES:-These are short much branched and tapering projections arising from the cell body.They receives sensation or stimulus, which may be physical, chemical, mechanical, or electrical. The stimulus is passed through cyton.

AXON (NERVE FIBRE):-It is a single, very long, cylindrical protoplasmic process of uniform diameter arising from the cell body. The axon has an insulating and protective sheath of myelin around it.

1 Nerve cell or CYTON transmits electrical impulses from one part to another part of the body.

2 Dendrites are specialised for acquiring information.

3 Axon is specialised for transferring information acquired by dendrites.

HUMAN BRAIN (ENCEPHALON):-

The brain is the highest coordinating centre in the body. It is situated in the cranial cavity. The brain is soft whitish organ. It forms about 98% of the weight of the whole central nervous system. It has about 100 billion neurons. Brain is surrounded by three membranes called meanings which provide protection to it. It consists of three parts.

1. FORE-BRAIN

2 MID-BRAIN

3 HIND-BRAIN

Parts of Human Brain

1. FORE-BRAIN:- It is the largest part of the human brain. It consists of following parts:-

a) CEREBRUM :- It is the largest part of the brain. It is the seat of intelligence, memory, thinking, emotions, ability, experience etc. It is subdivide into the lobes for the division of works.

Fore-Brain Parts

b) OLFACTORY LOBES:- It is concerned with sense of smell.

c) DIENCEPHALON:- It has hypothalamus that is the master endocrine gland of the body. Hypothalamus controls the normal temperature, food intake thirst etc.

2. MID-BRAIN:- It is significantly small region. It connects fore-brain with hind brain and also bears an important endocrine gland called, pituitary gland. The mid-brain controls reflex movements of the head, neck and trunk.

Mid brain

3. HIND-BRAIN:-

The hind brain consists of three parts, cerebellum, pons, and medulla oblongata. The cerebellum maintains posture, equilibrium and muscle tone pons controls some aspects of respiration. Medulla oblongata controls rate of heart beat, breathing movements.

Hind Brain

DIFFERENCES BETWEEN

CEREBRUM AND CEREBELLUM

CEREBRUM	CEREBELLUM
1. It is the part of fore-brain.	1. It is the part of hind -brain.
2. It is the largest part constituting 80% of the brain.	2. It is much smaller, constituting 12.5% of the brain.
3. It has two cavities called lateral ventricles.	3. Cavity is nearly absent.
4. It has two parts called cerebral hemispheres.	4. It has three parts two lateral cerebellar hemispheres and one central vermix.
5. It controls movements, speech, sight, smell, taste, hearing, intelligence etc.	5. It maintains equilibrium of the body.

RECEPTORS AND ITS TYPES:- A receptors is a nerve cell or group of nerve cells which is sensitive to a specific stimulus or to specific change in the environment.

Receptors and their Location

S. No	Name of Receptors	location	Stimulus
1	Thermo receptors	skin	Heat & cold
2	Photo receptors	eyes	light
3	Phonoreceptors	Ear	sound
4	Olfactory receptors	Nose	Smell
5	Gustato receptors	tongue	taste
6	Tango receptors	skin	touch

NEURON AND ITS TYPES:- The neuron are of three types:-

1. SENSORY(RECEPTOR) NEURONS:- These often occurs in sense organs, and receive stimuli by their dendrites.

2 MOTOR(EFFECTOR) NEURONS:- They transmit impulses from central nervous system towards effectors.

3 RELAYING(CONNECTORS) NEURONS:- These occurs in the central nervous system. These serve as links between sensory and motor neurons.

SPINAL CORD:- Spinal cord is a cylindrical structure and is about 45 cm long. It begins in continuation with the medulla oblongata of brain and extends downwards up to early part of lumbar region. Thirty-one pair of spinal nerves arise from the spinal cord. Spinal cord performs two important functions.

1 It conducts sensory and motor impulses to and from the brain.

2 It acts as a centre for the reflex actions. Thus, it reduces brain's work.

A . CENTRAL NERVOUS SYSTEM:- It consists of a the three types of nerves namely.

1. CRANIAL NERVES:- Cranial nerves arise from the brain and spread to various parts of the head. They are 12 pairs in number. Cranial nerves I, II and VIII are sensory nerves, cranial nerves III, IV, VI, XII are motor nerves; and cranial nerves V, VII, IX, and X are mixed nerves (containing both sensory and motor nerve fibres).

2. SPIANL NERVES:- Thirty-one pairs of spinal nerves arise from the spinal cord along most of its length and spread throughout the body (except head region). They carry both sensory and motor nerve fibres.

3. VISCERAL NERVES:- Apart from regulating normal functions of the body, many activities of the internal organs such as heart, kidney are controlled by specific set of nerves called visceral nerves.

B. AUTONOMIC NERVOUS SYSTEM:- It is the system which operates automatically or involuntarily. It includes all the responses against stimuli which are not under the control of system.

REFLEX ACTIONS:-

A reflex actions may be defined as a spontaneous, automatics and mechanical response to a stimulus, acting on a specific receptor, without the will of an animal. Reflex actions generally involves spinal cord for quick response to specific stimulus. However, information inout also goes on to reach the brain where thinking process occurs.

Examples:- Blinking of eyes, movement of diaphragm during respiration.

ADVANTAGES OF REFLEX ACTIONS:

1 It enables the body to give quick responses to harmful stimuli.

2 It minimizes the overloading of brain.

REFLEX ARC:- It is the pathway taken, by the nerve impulses and responses in a reflex actions, i.e, from the receptor organs, like, skin to the spinal cord and from the spinal cord to the effectors organs, like, muscles.

Reflex arc

CO-ORDINATION IN ANIMALS:-

In animals, endocrine glands release chemical substances called hormones. These are directly poured into the blood which circulates them to all the body tissues cells. Body tissue cells have specific molecules (receptors) to identify specific hormones either on their surfaces or inside their cytoplasm. Once the hormone combines with specific receptor present on target cells, It then transmits the information to bring about the effect. In case, the hormones are not secreted properly, there must be a kind of disorder in the body.

CO-ORDINATION IN PLANTS:-

In plants, chemical co-ordination occurs with the help of plant hormones (phytohormones) plants produce very small amounts of chemical substances called plant hormones or phytohormones which regulate their growth. Some of these chemical substances stimulate plant growth, while some others retard the retard of growth of plants. They are synthesised at places away from where they act and diffuse to the areas for actions, for example, Auxin promotes cell growth, gibberellins promote stem growth, cytokinins promote cell division and abscisic acid inhibits growth and its eppects include wilting of leaves.

PLANTS MOVEMENTS

1 NASTIC MOVEMENTS:- These are non-directional induced variation movements that occur due to turgor changes. These reveal immediate response to stimulus but do not involve growth.

Nastic movements are induced by external stimuli such as light, temperature, touch. However, these are not directional movements. Here, the part of the plant does not respond towards or away from the stimulus.

2 TROPIC MOVEMENTS OR TROPISMS:- Tropic movements are induced growth movements of curvature that occur due to differential growth. Directional movements plant in response to external stimuli are called tropisms or tropic movements.

TYPES OF TROPISM

PHOTOTROPISM:- It is the directional movement or orientation of the plant part in response to light stimulus.

GEOTROPISM:- It is the directional movement or orientation of the plant part in response to gravity.

CHEMOTROPISM:- It is the directional movement or orientation of the plants part in response to chemical stimulus

HYDROTROPISM:- It is the directional movement or orientation of the plant part in response to water stimulus.

PLANT HORMONE AND THEIR TYPES:

PLANT HORMONES & THEIR FUNCTIONS

1. Auxins

ü It promote cell enlargement and cell

ü Differnation in plants.

ü These also Promote stem and fruit growth.

2. Gibberellins

v It also promote growth in stems and fruits.

v These also induce parthenocopy in many plant.

3. Cytokinins

It promote cell divisions in plants.

These promote the opening of stomata.

4. Ethene

v It helps in breaking the dormancy in buds and seeds.

v It promotes yellowing and senescence of leaves.

5. Abscisic acid

v It promotes the dormancy in seeds and buds and thus inhibits growth.

v It also promotes the closing of stomata and tjus effects wilting of leaves.

DIFFERENCE BETWEEN HORMONES AND ENZYMES

HORMONES ENZYMES

1. They are produced by 1. They are produced by glands

ductless glands(endocrine glands). which have ducts.

2. Hormones may be other 2. Thses are always proteins in

than proteins, steroids, amines. nature.

3. They are specific chemical messengers, 3. They are biocatalysts, which

which act on specific tissue or organ. regulate the rate of

biochemical reaction.

DIFFERENTIATE BETWEEN

MEDULLATED AND NON-MEDULLATED NERVE FIBER.

MEDULLATED NON-MEDULLATED

1. Axon surrounded by 1. Myelin sheaths are

myelin sheath. absent.

2. Myelin sheath provides 2. Appears grey in colour

white colour to nerve fiber. due to absent in myelin

sheath.

3. Presence of nodes of ranveir. 3. Ranveir absent.

4. Conduction of nerve impulse 4. Conduction is slower.

in faster.

5. Found in brain and spinal 5. Found in sympatric and

cord. para-sympathetic nerves.

DIFFERENTIATE BETWEEN

ENDOCRINE GLAND AND EXOCRINE GLAND.

ENDOCRINE GLAND EXOCRINE GLAND

1 It is a gland which secretes its 1 It is a gland which

products directly into the blood. secretes its products

into a ducts.

2 It secretes hormone. 2 It secretes enzymes.

3 These are ductless glands. 3 These glands have

ducts.

4 Eg:- Pituitary gland. 4 Eg:- Saliva gland.

Dual glands

Dual glands are those which perform two types of functions in our body. These secrets some hormones for control and coordination and also help in some other activity of our body.

Eg:- Testes, ovaries and pancreas.

Difference between Nastic movements and tropic movements.

Nastic Movements Tropic Movements

1 These movement are neither 1 These movements are

away nor towards the stimulus. always in the direction

of the stimulus.

2 These movements are fast. 2 These movements are

slow.

3 These movements are exhibit 3 These movements are

by the flat organs like leaves exhibit by all parts of

and petals of flower of plant. of a plant.

4 These movements are dependent 4 These movements are

on growth. independent on growth.

Turgor movement

Turgor movement is due to the difference of turgidity of the cells in the lower half and upper half of pulvinus (petiole of leaf).

What is the difference between a reflex action and walking?

REFLEX ACTION WALKING

1 Reflex action is in born and 1 Walking is acquired

present in an individual right through learning.

from birth.

2 It is controlled by spinal 2 It is controlled by

cord. brain(hind brain).

3 It cannot be changed. 3 It can be changed.

4 It is an involuntary action with 4 It is a voluntary

out the will of the individual. action.

5 Response is given by muscles 5 Response is given by

or glands. muscles only.

What happens at the synapse between two neurons?

The minute gap which occur between two consecutive neurons is called as synapse. The information, acquired at the end of the dendritic tip of a nerve cell sets off a chemical reaction that creates an electrical impulse. This impulse travels from the dendrite to the cell body, and then along the axon to its end. At the end of the axon, the electrical impulse sets off the release of some chemicals. These chemicals cross the gap, or synapse, and start a similar electrical impulse in a dendrite of the next neuron.