3.维生素A原 、CH oxidation of aldehyde Retinoic acid ->Hormonal to acid (d) signal to epithelial CHs cells CHa CH CHs CHa CHs CHs CHs 7 CHs visible CHg light CHa CH3 CH3 Neuronal point of oxidationof signal cleavage 11 alcohol to to brain aldehyde 11 11 CH3 CH CH 1。CH2OH H人0 CH H Vitamin A 11-cis-Retinal CH3 4.缺乏症： CHa 夜盲症，干眼病，皮肤干燥 B-Carotene (a) 3.维生素A原： 维生素A原即胡萝卜素，有多种类似 物，其中以β-胡萝卜素活性最强. 4.缺乏症： 夜盲症，干眼病，皮肤干燥