Retina, Biology

RETINA -

  • It is inverted. Innermost, sensitive layer. The part of ratina which is attached to choroid is pars optica.
  • The part of retina attached to cilliary body is ora-serreta.
  • In retina 2 parts are clear -   (A) Pigmented layer          (B) Neuro-sensory layer.
  • Pigmented layer is of hexagonal or rectangular cells.
  • Fusein pigment present adopted to absorb light rays.
  • From these cells microvilli are given out to engulf extra pigment granules.
  • Inside it, a layer of rods and cones is present.
  • Rods are 1150 lakh and cones are 65 lakh.
  • Rods are mone long, meant to judge abject in dim light in it rodopsin (retinine + opsine or skotoprine) present for it vitamin A (ratinol) is necessary i.e. in defficiency of vit A. night blindness (nyctalopia) is caused.
  • Rhodopsin is known as visual purple.
1967_visual purple.png

  • Cones are meant to judge objects in sharp light due to visual violet iodopsin. & to distinguish colours.
  • In cones erythrolab (red), chlorolab (green) & cynolab (blue) are present.
  • Most domestic animals lack colour vision.
  • They see objects in shades of grey (Monochromic vision)
  • In squirrel, hen rods are absent. In rat, shrew & bat cones are absent.
  • Layer of rods and cones is attached to two layers of bipolar neurons where light impulses are converted in to nerve impulses so it is a Bio chemical process.
  • Neurons are attached to ganglions layer from where optic nerve fibres originate to form optic nerves.

689_retine.png

Posted Date: 10/3/2012 4:18:32 AM | Location : United States







Related Discussions:- Retina, Assignment Help, Ask Question on Retina, Get Answer, Expert's Help, Retina Discussions

Write discussion on Retina
Your posts are moderated
Related Questions
Briefly explain Lichens organism? Lichens are unique organisms consisting of a symbiotic relationship between a fungus and a photosynthetic organism. They represent a type of s

Define Procedure for Testing the Presence of Urea in Milk? 1. To 0.5 ml of milk add 0.5 ml of  DMAB solution  (prepared by dissolving 0.4 gm of p-dimethyl amino benzaldehyde po

why the small intestine is longer in herbivores as comparison to carnivores animals

Photosynthetically Active Radiation This is usually in direct proportion with the incident solar radiation, you know that tropic$ are probably the best illuminated part of the

Mixed Tricuspid Stenosis and Regurgitation:  Rheumatic involvement of the tricuspid valve is often seen in association with involvement of mitral and rarely aortic valve. Isolated

Q. What are plasmids? And what is the significance of plasmids for the recombinant DNA technology? Plasmids are circular fragments of DNA that are accessories to the main bacte

Q. Show overall management of diabetes? Diabetes as we all know is a disease with ever increasing prevalence in' our country. It can be described as a disease characterized by

Another important genus of mycotoxin producers is Fusarium, many species of which produce members of the trichothecene family of mold metabolites like deoxynivalenol, neosolaniol a

State the series of stimuli ERPs a series of stimuli such as tones or light flashes are presented to the participant, and the raw EEG for a precise one or two second period fol

What is the monohybridism? The Monohybridism is the study of only one characteristic in the crossing of two pure individuals (hybridization) for that characteristic.