BIO 121 Lecture Notes - Lecture 22: Arthropod, Sarcomere, Prati
Document Summary
Photoreceptors: sensory cells with light-absorbing pigment molecules (all light detectors: genes that specify where and when they arise during embryonic development are shared among flatworms, annelids, arthropods, vertebrates. Nocturnal mammals have high proportion of rods in the retina keen night vision. Light-detecting organs: ocelli in planaria (eyespots): located in the head region; they receive light only through an opening where there are no pigmented cells, compound eyes: contain many ommatidia detectors that each have its own light-focusing lens. Detects light from a tiny portion of the visual field. Effective and detecting movement; have wide field of view: single-lens eyes: found in jellies, worms, molluscs, vertebrates. Pupil and iris that contracts/expands to let more/less light. Rods: sensitive to light, do not distinguish color: allow night vision (black and white) Cones: provide color vision: 3 types of cones (red, green, blue) Sensory transduction (cis to trans-retinal conversion of light)
