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

Explain penicillin allergy, Penicillin allergy Cefazolin is often used ...

Penicillin allergy Cefazolin is often used for prophylaxis in penicillin-allergic patients, but such patients rarely may have allergic reactions to cephalosporins. When allergy

Define eye balling, Q. Define Eye Balling? Ans. Two-dimensional ec...

Q. Define Eye Balling? Ans. Two-dimensional echocardiography provides a good visual perception of cardiac functions. With experience, the echocardiologist learns to percei

Chordata, what is meant by "pelagic"?

what is meant by "pelagic"?

Metabolism, What is Metabolism ?  The  sum total of vital activities ( ...

What is Metabolism ?  The  sum total of vital activities ( movements , nutrition, growth, respiration, excretion , reproduction, behaviour ,etc.  Is the  life  of a living  bei

Define the theory or principle of drying, Define the Theory or Principle of...

Define the Theory or Principle of Drying? Drying can be illustrated as the application of heat under controlled conditions to eliminate the majority of the water generally avai

How does the intensity of simple diffusion differ, How does the intensity o...

How does the intensity of simple diffusion differ in relation to the concentration gradient of the moved substance? The higher the concentration gradient of a substance the ext

What is crystallization of a virus, What is crystallization of a virus? Wha...

What is crystallization of a virus? What is the importance of this process? Crystallization is the method of transformation of viral components into organized solid particles.

Write the definition of counselling, Q. Write the definition of counselling...

Q. Write the definition of counselling? The counselling process, involves various steps in a sequence as given below: 1. Rapport-Building 2. Locating the Problem 4. Pl

Give an example of structural protein, Give an example of each of the follo...

Give an example of each of the following types of proteins: a. Enzyme b. Structural protein c. Motor protein

Neuston - aquatic ecosystem, Neuston - Aquatic Ecosystem These are una...

Neuston - Aquatic Ecosystem These are unattached organisms which live at the air-water interface such as floating plants and several types of animals. Some spend most of their

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