NERVOUS SYSTEM OF FISHPHYSIOLOGY OF FISH SHORT NOTES

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NERVOUS SYSTEM • OF FISH|PHYSIOLOGY OF FISH SHORT NOTES • LIKE AND SUBSCRIBE • SCIENCE PPT WORLD • CENTRAL NERVOUS SYSTEN • derived from the neural ectodermal part of ectoderm • include brain and spinal cord • BRAIN- •  The fish brain varies from species of the same group •  Amount of neuroglia and fibre also various species of fishes •  Cerebro-somatic index •  CSI=wt. Of brain/wt. Of body-wt. Of brain 100 •  Brain include part- •  telencephalon •  diencephalon •  mesocephalon • Rhombecephalon •  The nervous system response to any type of external stimuli. •  Various component of nervous system include the sensory structure, nerve, brain and spinal cord. •  Any type of stimuli receive by receptor is carried by afferent nerve fibre to the central nervous system. •  The response is conveyed to the effecter through efferent nerve fibre •  Nervous and endocrine system are highly interdependent •  Anterior most region of the brain •  Also called cerebral hemisphere in adult •  It is primarily devoted to the reception, elaboration and conduction of olfactory impulses •  In teleosts and other ray-finned actinoptergians, the cerebral hemisphere are of everted type. •  The function of telencephalon is fishes appear to chiefly one of smell reception. •  It regarded as the sight area in fishes •  It is second part of the brain •  Also called tween brain •  The diencephalon is composed of epithalamus, a middle thalamus, a ventral portion of called hypothalamus •  Epithalamus-prences of epiphysial apparatus •  Hypothalamus- it include optic chiasma and infundibulum and hypophysis •  Thalamus- it consist thalamic fibre tract •  Third portion of the brain , relatively large •  Consist of dorsal roof and ventral tegmentum •  tectum is composed of various type of neurons •  It posses several layer of nerve cells •  the cavity of latter is called optocoel with joint mesocoel •  An extend of cerebellum in to mesocoel seen in certain fish •  It is 4th and 5th division of brain , the metacephalon and myelecphalon respectively •  Metacephalon - cerebellum develop underlying enlarge medulla, •  In adult fish cerebellum consist a large corpus and a pair of lateral auricular •  Myelecphalon - medulla oblongata main part •  Which lead sensory nerve except smell 1 ,and sight 2, •  A pair of vagal lobe found in the side of medulla oblongata • Is uniform structures extend for the entire length of the body •  It lie protected into the vertebral canal along with envelop •  the shape quadrilateral in jawed fishes •  A dorsal fissure is prominent while the ventral fissure is entirely lack in teleosts •  The central canal in the centre of spinal cord is thin with ependymal layer •  it surrounded by grey matter • Is uniform structures extend for the entire length of the body •  It lie protected into the vertebral canal along with envelop •  the shape quadrilateral in jawed fishes •  A dorsal fissure is prominent while the ventral fissure is entirely lack in teleosts •  The central canal in the centre of spinal cord is thin with ependymal layer •  it surrounded by grey matter • • Is uniform structures extend for the entire length of the body •  It lie protected into the vertebral canal along with envelop •  the shape quadrilateral in jawed fishes •  A dorsal fissure is prominent while the ventral fissure is entirely lack in teleosts •  The central canal in the centre of spinal cord is thin with ependymal layer •  it surrounded by grey matter • • • #SCIENCE PPT WORLD#EDUCATION • • • • • Music provided by http://spoti.fi/NCS

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