Organization of Sensory Systems

• Sensory receptor cells can be classified in four different ways
• Sensory receptor cells transduce and encode sensory information

Mechanoreception and Touch

• Insect bristle sensilla exemplify mechanoreceptor responses
• Touch receptors in the skin of mammals have specialized endings
• Proprioceptors monitor internal mechanical stimuli

Vestibular Organs and Hearing

• Insects hear with tympanal organs
• BOX 14.1 Echolocation
• Vertebrate hair cells are used in hearing and vestibular sense
• Vertebrate vestibular organs sense acceleration and gravity
• Sound stimuli create movements in the vertebrate cochlea that excite auditory hair cells
• The localization of sound is determined by analysis of auditory signals in the CNS

Chemoreception and Taste

• Insect taste is localized at chemoreceptive sensilla
• Taste in mammals is mediated by receptor cells in taste buds
• BOX 14.2 Genomics and sweet taste in hummingbirds

Olfaction

• The mammalian olfactory epithelium contains odor-generalist receptor cells
• The vomeronasal organ of mammals detects pheromones

Photoreception

• Photoreceptor cells and eyes of different groups have evolved similarities and differences
• Rhodopsin consists of retinal conjugated to opsin,  a G protein–coupled receptor
• Phototransduction in Drosophila leads to a depolarizing receptor potential
• The vertebrate eye focuses light onto retinal rods and cones
• Rods and cones of the retina transduce light into a hyperpolarizing receptor potential
• Enzymatic regeneration of rhodopsin is slow

Visual Sensory Processing

• Retinal neurons respond to contrast
• The vertebrate brain integrates visual information through parallel pathways
• BOX 14.3 What roles do individual neurons play in higher visual integration?
• Color vision is accomplished by populations of photoreceptors that contain different photopigments

Copyright 2016 Sinauer Associates