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
Andalusian chickens may be either black, white, or gray. The gene for black is not dominant over the gene for white, nor is the gene for white dominant over the gene for black. Whe

Facilitation Model - Models of Succession This is considered as the classical model of succession. It is based on the assumption that species of a previous stage are replaced

Describe the Initiation of Visual Impulse When light falls on the retina it is absorbed by the photosensitive pigments of rods (rhodopsin) and cones (photopsin). It initiates

What is the type of circulatory system present in arthropods? Do these animals have heart and respiratory pigments? In arthropods the respiratory system is open (lacunar). Blo

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

However, according to conventional principles of economic analysis it is necessary that a resource is used for it to acquire a value. Consequently economists traditionally value bi

Which of the following variations on translation would be most disadvantageous for a cell? A) translating polypeptides directly from DNA B) using fewer kinds of tRNA C) having only

What is agamospermy? How is agamospermy dissimilar from parthenogenesis and parthenocarpy? i. How can haploid plants be increased in the laboratory? ii. Name the plant f

Q. What is Peri-Implant Disease? The term peri-implantitis is used to describe the boneloss around an implant. This may be induced by stress or bacteria or a combination of bot

Q. How to calculate Fractional Shbrtening? With the cursor- beam cutting the left ventricle just beyond the tips of mitral valve in an adequate parasternal long axis view,