ZOO 2090 Lecture Notes - Lecture 20: Sclera, Platypus, Pigment

• School: University of Guelph
• Department: Zoology
• Course: ZOO 2090
• Professor: Jinzhong Fu

Document Summary

Function: the sense organs perceive and integrate sensation, and initate action. Components of sensory organs: sensory receptor: is usually composed of the dendrites of a neuron and can include tissue that amplifies the stimulis. The receptor is a transducer that transforms a stimulus into an electrical impulse or burst of electrical impulses that spread to the cell body and along its axon to other neurons, usually in the central nervous system. Photoreceptors: cells capable of phototransduction i. e. generate electrical potential with photon absorption. Photoreceptor neurons are organized into the complex epithelium of the retina in eyes. Retina: sclera: rigid housing of the ye, choroid layer: nourishment, pigment layer: prevents reflection, lens and cornea: form image. Adaptation to dim light: large eyes: large pupil, large lens close to retina, few cones or none, slender rod cells are closely packed, tapetum lucidum (mirror) can be present (e. g. deer in the headlights)