The working together of the various organs of an organism to adjust vital activities of life is called coordination.

Coordination is mainly of two types :-

1. Nervous coordination.

2. Chemical coordination.

Nervous coordination in animals

There are two systems to control and coordinate various activities in animals -

(A) Nervous system (B) Endocrine system

Nervous system

Neuron

· The structural and functional unit of nervous system.

· Neuron (nerve cell) is the longest cell of human body (up to 100 cm)

· Neuron is made up of -

(i) Cell body

(ii) Cell processes (axon and dendron)

(i) Cell body :- or Cyton or Soma or Perikaryon

· It contains granular cytoplasm which is called neuroplasm.

· Many small fibrils are present in the neuroplasm called neurofibrils for the conduction of nerve impulses.

· Rough endoplasmic reticulum coils around the ribosome and form a granule like structure called as Nissl's granule or Tigroid body.

· Nissl's granule is the centre of protein synthesis.

· Energy for conduction of nerve impulses is provided by numerous mitochondria.

· Except centriole, all other cell organelles are found in neuroplasm.

(ii) Cell process :-

(a) Axon :-

· It is longest cell process of cyton, its diameter is uniform and it contains axoplasm.

· Axoplasm of axon contains only neurofibrils and mitochondria.

· Nissl's granules are absent.

· Axon is covered by axolemma.

· Axolemma may be covered by a layer of phospholipids which is called as medulla or myelin sheath.

· Myelin sheath acts as insulator and prevents leakage of ions.

· Myelin sheath is discontinuous around the axon. These interruptions where axon is uncovered by myelin sheath are called nodes of Ranvier.

· Axon produces centrifugal conduction i.e. nerve impulse travels away from the cell body.

· The terminal ends of axon are branched which are called telodendria.

· Each telodendron ends in a swollen knob called synaptic knob.

· Nerve fibres in which myelin sheath is present, are called medullated or myelinated nerve fibres and nerve fibres without myelin sheath, are called non-medullated or non-myelinated nerve fibres.

Axon is functional part of nerve cell, therefore term "nerve fibre" usually refer to axon.

(b) Dendron :-

· It is small cell process.

· It's fine branches are called 'dendrites'

· Dendron receive the stimuli and produce centripetal conduction i.e. nerve impulse travels towards the cell body.

· It is not covered by myelin sheath.

Differences between Axon and Dendron -

Differences between medullated and non-medullated nerve fibre.

Type of Neurons -

Sensory organ Joins sensory CNS to effector organ to CNS to motor neuron

synapse : The junction between two adjacent neurons i.e.

between the axon ending of one neuron and dendrites of the next.

Nerve impulse :- It is an electro-chemical information (signal) passing through neuron.

Neurotransmitters or Neurohormones - Chemical substances which either transmit or inhibit the message from one neuron to another.

Stimulatory Neurotransmitters Inhibitory Neurotransmitters

Stimulate impulse at synapse Inhibit impulse at synapse

e.g. - Acetyl choline (Ach) e.g. - GABA

(Gamma Amino Butyric Acid)

Working of neuron or Transmission of nerve impulse :-

 

Central Nervous system (CNS) :-

· CNS consists of the brain and the spinal cord.

(A) BRAIN

· Brain is the most important part of human body.

· Brain is situated in a cranial box (cranium) which is made of bones.

· Meninges(Menix) :- Brain is covered by three membranes of connective tissue, termed as meninges.

(i) Dura Mater :- It is the first and the outermost membrane which is thick, very strong and nonelastic.

(ii) Arachnoid Mater :- It is middle, thin, delicate and non-vascular membrane found only in mammals.

(iii) Pia Mater :- It is innermost, most vascular, thin and transparent membrane.

The space between the arachnoid and pia mater is filled with a fluid called cerebrospinal fluid (CSF). It protects the brain from mechanical shocks.

Meningitis :- Any inflammation of meninges is called meningitis.

Weight of brain :- In adult male 1400 gm, female 1250 gm.

Parts of Brain:

(1) Fore brain

(2) Mid brain

(3) Hind brain

(a) Cerebrum (a) Crura cerebri (a) Cerebellum

(b) Diencephalon (b) Corpora quadrigemina (b) Pons

(c) Medulla oblongata

(1) Forebrain (Prosencephalon) :-

 (a) Cerebrum (Telencephalon) :-

(i) Anterior :- Frontal lobe for intelligence, knowledge, abstract, reasoning,creative ideas and memory.

(ii) Middle :- Parietal lobe for taste, writing, pain, touch and pressure.

(iii) Lateral :- Temporal lobe for language, hearing and smell.

(iv) Posterior :- Occipital lobe meant for vision.

(b) Diencephalon :-

· It is small and posterior part of fore brain.

· It is covered by cerebrum.

(i) Thalamus :-

· They act as relay station.

· They receive all sensory impulse from all parts of body and these impulses are send to the cerebral hemispheres.

(ii) Hypothalamus :-

· It forms lower lateral wall of diencephalon.

· A cross like structure is found on anterior surface of hypothalamus called as optic chiasma.

· Pituitary body is attached to middle part of hypothalamus by infundibulum.

· Functions :

(iii) Epithalamus :-

(2) Mid brain (Mesencephalon) :-

(a) Cerebral peduncles (Crura cerebri) :-

(b) Optic lobes (Corpora Quadrigemina) :-

(3) Hind Brain (Rhombencephalon) :-

(a) Pons :-

(b) Cerebellum :-

 Function : To maintain body balance & posture. It is responsible for percision of voluntary actions.

(c) Medulla oblongata :-

 Functions:

(i) It controls all the involuntary activities of the body. e.g. - heart beats, respiration, blood pressure salivation.

(ii) It also concerned with some reflexes- sneezing reflex, coughing reflex, vomiting reflex, yawning reflex.

 

(B) Spinal Cord

Functions of spinal cord -

(i) Spinal cord regulates and conducts the reflex actions.

(ii) It acts as bridge between brain & organs of the body.

(iii) It also provides relay path for the impulses coming from brain.

Chemical coordination in animals (ENDOCRINE SYSTEM)

Pancreas has both exocrine and endocrine part, so it is also called mixed gland or common gland or heterocrine gland.

Hormones

Discovery :-

 Physical & chemical properties of hormones :-

Plant movements & plant hormones

 Plant movement : The movements in plants are not as apparent as in case of animals. Plants generally show movements at a very slow rate. The higher plants are fixed to the substratum by means of roots. They can not move from one place to another. They, therefore show movement of their organs only.

Classification of plant movements :

Plant movements are broadly classified into two types :

(1) Tropic movements                                       (2) Nastic movements

(Directional)                                                     (Non-directional)

(i) Phototropism                                                 (i) Seismonasty

(ii) Geotropism                                                   (ii) Nyctinasty

(iii) Chemotropism

(iv) Hydrotropism

(v) Thigmotropism (Haptotropism)

1. Tropic movements :- Directional movements or orientations of specific part of a plant in response to external stimuli such as light, force of gravity, chemicals, water are called tropisms or tropic movements.

Tropic movements are very slow. The movement of the plant part can be either towards the stimulus (positive tropism) or away from the stimulus (negative tropism).

(i) Phototropism :- Definite direction movement in relation to light.

(ii) Geotropism :- Definite direction movement in relation to gravity.

(iii) Chemotropism :- Definite direction movement in relation to chemicals.

e.g. - Movement of pollen tubes and fungal hyphae.

(iv) Hydrotropism :- Definite direction movement in relation to water.

e.g. - Roots of seedlings.

(v) Thigmotropism (Haptotropism) :- Definite direction movement in relation to contact or support. The pea plant develops tendrils which help it to climb up other plants or fences or some other support. These tendrils are sensitive to touch.

e.g. - Tendrils, haustoria of Cuscuta.

(2) Nastic movements :- 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. Nastic movements include :-

 (i) Seismonasty :- The turgor changes occur in thin-walled cells of pulvinus, causing folding and drooping of the compound leaves. Such movements occur in response to touch (shock). These movements are very quick and are best seen in 'touch-me-not' plant (Mimosa pudica), also called 'Chhui-mui' or 'Lajwanti' or
'sensitive plant'. If we touch the leaves of the chhui-mui plant with our finger, we find that all its leaves immediately fold up and droop. After sometime, the leaves regain their original status. Here, no growth is involved. Instead, plant cell change shape by changing the amout of water in them (turgor changes), resulting in folding up and drooping of leaves.

(ii) Nyctinasty :- Sleep movements - Due to day and night.

e.g. - Daily movement of flowers, leaves, stomata.

Chemical Coordination in Plants

(i) Auxins

(ii) Gibberellins

(iii) Cytokinins

(iv) Abscisic acid

(v) Ethylene

(i) Auxins :-

Functions of Auxins

              (ii) Gibberellins (GA) :-

Functions of Gibberellins

 (iii) Cytokinins (CK) :-

Functions of Cytokinins

Promote cell division and elongation

 (iv) Abscisic Acid (ABA) :- It is also known stress hormone ordormin.

 Functions of Abscisic Acid (ABA)

(v) Ethylene (Gaseous hormone) :-

Functions of Ethylene (Gaseous hormone)