视觉是由眼、视神经和视觉中枢的共同活动完成的。外界物体发出的光,透过眼的透明组织发生折射,在眼底视网膜上形成物象,视网膜感受光的刺激,并把光能转变成神经冲动,再通过视神经把神经信息传到大脑皮质的视觉中枢,从而产生视觉。 视网膜中的锥体细胞和杆体细胞是直接感受光刺激的感受器,分别司明视觉和暗视觉。这两种感光细胞都含有感光色素,在光的作用下发生化学变化而产生明、暗视觉。杆体细胞中的感光色素称为视紫红质,是 Vision is done by the common activities of the eye, optic nerve and visual center. The light emitted by the external object refracts through the transparent tissue of the eye, forms an image on the fundus retina, stimulates the light of the retina, transforms the light energy into a nerve impulse, and then sends the nerve information to the visual cortex of the cerebral cortex through the optic nerve, Thus producing vision. Pyramidal cells and rod cells in the retina are photoreceptors that directly sense photoreceptors, respectively, by Seming’s vision and dark vision. Both photoreceptors contain sensitizing pigments that undergo chemical changes under light to produce bright and dark vision. Photosensitizing pigment in rod cells is called rhodopsin, is