BIO 123 Chapter Notes - Chapter 50: Optic Chiasm, Visual Cortex, Photopsin
27 Mar 2019
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Concept 50. 3: the diverse visual receptors of animals depend on light-absorbing pigments. Photoreceptors: sensory cells that contain light-absorbing pigment molecules. In planarians: ocelli located in the head region, photoreceptors in each ocellus receive light only through an opening where there are no pigmented cells. Insects, crustaceans, some polychaete worms have compound eyes. Compound eyes: type of multifaceted eye in insects and crustaceans consisting of up to several thousand light-detecting, focusing ommatidia. Ommatidia: one of the facets of the compound eye of arthropods and some polychaete worms. Camera-like eye found in some jellies, polychaete worms, spiders, and many molluscs. Pupil: a small opening through which light enters. Iris: expands or contracts, changing the diameter of the pupil to let in more or less light. Lateral inhibition: sharpens edges and enhances contrast in the image -- occurs in brain as well as the retina. Receptive field: the part of the visual field to which that ganglion cell can respond.
