Retina, Biology

Assignment Help:

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


Related Discussions:- Retina

Simple lipids, SIMPLE  LIPIDS They are lipids formed of fatty acids an...

SIMPLE  LIPIDS They are lipids formed of fatty acids and alcohol without any additional group. e.g. fats or true fats,wax,cutin, suberin. Simple lipids are mainly of 2 types

What is the difference between aerobic and anaerobic beings, What is the di...

What is the difference between aerobic and anaerobic beings? Aerobic organisms are those whose cells do not survive without oxygen as they depend on aerobic cell respiration to

Oxidative decarboxylation of pyruvate, Oxidative decarboxylation of pyruvat...

Oxidative decarboxylation of pyruvate Oxidative decarboxylation ofpyruvate : This is an important step in tissues with high oxidative capacity such as cardiac muscle, whereby

Define changes in body composition due to microgravity, Define Changes in B...

Define Changes in Body Composition due to Microgravity? Major stress in space is microgravity. Microgravity refers to an environment in which there is very little net gravitat

What is microtubule assembly, Microtubule assembly: A) generally originates...

Microtubule assembly: A) generally originates in the centrosome. B) Occurs only during mitosis. C) Occurs randomly throughout the cell. D) Is regulated by myosin. E) Is inhibited d

Define absorption, Define Absorption, Storage and Elimination of niacin? ...

Define Absorption, Storage and Elimination of niacin? Nicotinic acid and nicotinamide are rapidly absorbed from the intestine rather than the stomach. At low concentrations, a

Plants of estuary, Plants of Estuary The plants of the estuary are of ...

Plants of Estuary The plants of the estuary are of four basic types: Phytoplankton, Marginal marsh vegetation, Mud-flat algae and Epiphytic plants

Define the surgery process for cancer patient, Define the Surgery Process f...

Define the Surgery Process for Cancer Patient? Surgery is generally conducted in the absence of metastasis i.e. when a tumor is localized. Nutrition support would vary dependin

Discuss about intracellular perfusion fluid, At 1 AM, a healthy squid giant...

At 1 AM, a healthy squid giant axon is placed in a bath of normal squid physiological extracellular saline and is internally perfused with normal squid intracellular saline.  I

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd