Retinal, also called retinaldehyde or vitamin A aldehyde, is one of the many forms of vitamin A (the number of which varies from species to species). Retinal is a polyene chromophore, and bound to proteins called opsins, is the chemical basis of animal vision. Bound to proteins called type 1 rhodopsins, retinal allows certain microorganisms to convert light into metabolic energy.

Vertebrate animals ingest retinal directly from meat, or produce retinal from one of four carotenoids (beta-carotene, alpha-carotene, gamma-carotene, and beta-cryptoxanthin), which they must obtain from plants or other photosynthetic organisms (no other carotenoids can be converted by animals to retinal, and some carnivores cannot convert any carotenoids at all). The other main forms of vitamin A, retinol, and a partially active form retinoic acid, may both be produced from retinal.

Invertebrates such as insects and squid use hydroxylated forms of retinal in their visual systems, which derive from conversion from other xanthophylls.

Read more about Retinal:  Vitamin A Metabolism, Vision, Type 1 Rhodopsins, History

Other articles related to "retinal":

Central Retinal Vein
... The central retinal vein (retinal vein) is a short vein that runs through the optic nerve and drains blood from the capillaries of the retina into the larger veins outside the eye ... of the veins of the orbit of the eye varies between individuals, and in some the central retinal vein drains into the superior ophthalmic vein, and in some it drains directly into the cavernous sinus ...
Macular Telangiectasia - Management
... OCT can help to identify the abnormal vessels, pigment plaques, retinal crystals, fovealatrophy and intra-retinal cysts associated with this disorder ... over 10 to21 years showed deterioration of vision in more than 84% of eyes, either due to intra-retinal edema and serous retinal detachment (Type 1) or pigmented RPE scar formation or CNV (Type 2) ... actually enhance vessel ectasia and promote intra-retinal fibrosis in these individuals ...
Macular Telangiectasia - Pathophysiology
... unknown, it has been speculated that chronic venous congestion caused by obstruction of the retinal veins as they cross retinal arteries at the horizontal raphe may be a contributory ... It is thought that this collective loss of retinal cells may induce intraretinal neovascularization and, ultimately, subretinal or choroidal neo-vascularization (CNV) ...
Blood–retinal Barrier
... The blood–retinal barrier, or the BRB, is part of the blood–ocular barrier that consists of cells that are joined tightly together to prevent certain substances from entering ... It consists of non-fenestrated capillaries of the retinal circulation and tight-junctions between retinal epithelial cells preventing passage of ...