Photoreceptors, Biology

Assignment Help:

Photoreceptors

Photoreceptors are concerned in absorption of light by photosensitive pigments. The chemical change involved produces the impulse concerned in the nerve cells. The pigments involved are carotenoid derivatives containing retinine (vitamin A aldehyde) combined with a protein (opsin). Rhodopsin is one of the general pigments. Simple eyes are extremely common; extremely differentiated compound eyes have evolved in many arthropods, and well differentiated camera type eyes, as comparable to vertebrate eyes occur in cephalopods. You will see among several non-chordates a variety of eyes ranging between these extremes. Simplest eyes in Platyhelminthes and annelids are in the form of pigment spots containing sensory cells associated with pigment cells. They serve differentiation of light from darkness. In several polychaetes they reach higher level of organization. The cup may often secrete a lens. The cephalopod eye is the result of highest elaboration of vesicular eye. Actually the eye in Octopus reaches the structural complexity of that of vertebrate eye, resembling it in considerable details. Though, the cephalopod retina is direct type with sensory ends of the receptor cells directed towards the source of light whereas the retina of vertebrate eye is inverted with the sensory ends turned away from the source of light.


Related Discussions:- Photoreceptors

Adverse effect to intestinal mucosa, Q. Adverse effect to intestinal mucosa...

Q. Adverse effect to intestinal mucosa? Alcohol: Alcohol is known to cause damage to intestinal mucosa independent of gastric acid content. Thus high amounts are not advised.

Endocrine, Adrenal causes of hypertension are: 1) Excess of aldosterone ...

Adrenal causes of hypertension are: 1) Excess of aldosterone production in primary aldosteronism. The diagnosis may be suspected when persistent hypokalemia is detected. Most of

Fungai, introduction in fungai

introduction in fungai

What would most likely be true, You are given a metaphase chromosome prepar...

You are given a metaphase chromosome preparation (a slide) from an unknown organism that contains 12 chromosomes. Two that are clearly smaller than the rest appear identical in len

Explain the absorption and transport of vitamin e, Explain the Absorption a...

Explain the Absorption and Transport of Vitamin E? Absorption of vitamin E from the intestine depends on adequate pancreatic function, biliary secretion and micelle form

Define caution for the use of pipettes - food microbiology, Caution for the...

Caution for the use of Pipettes - Food Microbiology? (1) Never do pipetting with mouth. (2) For culturing, sterilized pipettes should be used. (3) Never keep pipettes on

Death, DE A T H - It is terminal end of the degeneration changes of ...

DE A T H - It is terminal end of the degeneration changes of old age. Death occurs when vescular system & respiratory system stop working. Failure of nervous system ma

Classification of hypertension, Q. Show basic Classification of hypertensio...

Q. Show basic Classification of hypertension? Unlike many other diseases, hypertension develops insidiously (without symptoms). In 90% of hypertension cases, the cause is unkn

Professional guidance in diabetes mellitus, Counselling refers to professi...

Counselling refers to professional guidance in resolving personal conflicts and emotional problems. Counselling is a process which enables a person to identify problems and find a

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