BRAIN STRUCTURE

Human brain is the most advanced and well developed of all animals. It is encased in a bony case called cranium or skull which protects it from external injuries.
The brain is covered with meninges.Between the meninges , the space is filled with cerebrospinal fluids.
These are
DURAMATER -It is the outer tough and fibrous membrane.
ARACHNOID -It is  a middle delicate membrane.
PIAMATER- It is inner thin and highly vascular membrane.
ENCEPHALOGY is the  study of structure , working and function of brain.
The brain is differentiated into three parts:Fore brain,Mid brain and Hind brain.

FOREBRAIN:

1. Olfactory lobes
2. Cerebrum
3. Diencephalon

MIDBRAIN

1. Cerebral peduncles
2. Corpora quadrigemina

HIND BRAIN

1. Cerebellum
2. Pons
3. Medulla

CSF : It occurs between piamater and arachnoid and cavities of brain and sppinal cord.The fluid is rich in nutrients, hormones and respiratory gases.It supplies food , oxygen and removes wastes from brain, carries hormones from the brain and protects CNS from shocks. It is filtered from the blood and passes back into the blood

COMPONENTS OF NERVOUS SYSTEM X

                                           NERVOUS SYSTEM

1. CENTRAL NERVOUS SYSTEM  (CNS)
2. PERIPHERAL NERVOUS SYSTEM (PNS)
3. AUTONOMIC NERVOUS SYSTEM (ANS)

CNS

1. BRAIN 
2. SPINAL CORD

PNS

1. CRANIAL NERVES
2. SPINAL NERVES

ANS

1. SYMPATHETIC NERVOUS SYSTEM
2. PARASYMPATHETIC NERVOUS SYSTEM

NERVOUS SYSTEM

COORDINATION

It is the process through which two or more organs of an organism interact and complement the functions of each other or work together to adjust the vital activities of life.

NEED OF NERVOUS SYSTEM

1. To enable us to remeber, think and reason.
2. To coordinate working of various glands or tissues.
3. To regulate in voluntary activities of breathing , alimentary canal etc.
4. To regulate voluntary muscular activities.
5. To respond to changes in internal as well as external environment.

ROLE OF RECEPTORS

These are sensory cells that receive stimulus nad cinvert them into electric nerve impulses. The receptors are also called transducers as they convert one form of energy to another.
Examples

1. Photoreceptors in eyes
2. Phonoreceptors in internal ears
3. Olfactoreceptors in nose
4. Gustatoreceptors cin tongue
5. Mechanoreceptors in skin

INTRODUCTION TO CONTROL AND COORDINATION.

Stimulus
Any major or minor change in environment.

Receptor
Cell, tissue or organ sensitive to stimulus

In all animals control is achieved through

1. Neural System
2. Endocrine System

Difference between the two are as follows:

1. Nervous system is made up of nerve cells while endocrine system is made up of secretory cells.
2. Messages are transmitted in the form of electrical impulses in nervous control while these are transmitted as chemicals in hormonal control.
3. Impulses travel rapidly while hormone action is slow.
4. Effect of nerve impulse lasts for a short duration of time while effect of hormone lasts longer.
5. Impulses are transmitted along the nerve fibre while hormones are transmitted via bloo

CLASS IX FISH PRODUCTION

Fisheries can be categorised into two types.
1. Fin fisheries
2. Non-fin fisheries.
The fin fisheries of true fishes, whereas the non-fin fisheries is the fisheries of organisms other than true fish like prawn, crab, lobster, mussel, oyster, sea cucumbers, frog, sea weeds, etc.

Fin fisheries can be further categorised into two types
1. Capture fisheries
2. Culture fisheries.
Capture fisheries is exploitation of aquatic organisms without stocking the seed. Recruitment of the species occur naturally. This is carried out in the sea, rivers, reservoirs, etc. Fish yield decreases gradually in capture fisheries due to indescriminate catching of fish including brooders and juveniles. Overfishing destroys the fish stocks. Pollution and environmental factors influence the fish yield. The catches include both desirable and undesirable varieties.

Culture fisheries is the cultivation of selected fishes in confined areas with utmost care to get maximum yield. The seed is stocked, nursed and reared in confined waters, then the crop is harvested. Culture takes place in ponds, which are fertilized and supplementary feeds are provided to fish to get maximum yield. In order to overcome the problems found in capture fisheries to increase the production, considerable attention is being given to the culture fisheries.

Culture fisheries is conducted in freshwater, brackish water and sea waters. With the development and expansion of new culture systems, farming of a wide variety of aquatic organisms like prawns, crabs, molluscs, frogs, sea weeds, etc. have come under culture fisheries. Due to the culture of a variety of aquatic organisms, culture fisheries has been termed as aquaculture. http://agritech.tnau.ac.in/fishery/fish_classification.html