Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh Edition Solomon Berg Martin Chapter 41 Sensory Reception
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Sensory receptors Neuron endings Specialized receptor cells in close contact with neurons Sense organs Sensory receptors Accessory cells
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Mechanoreceptors Transduce mechanical energy Animal functions –Feeling –Hearing –Maintaining balance
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Chemoreceptors Transduce certain kinds of chemical compounds Allow taste and olfaction
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Thermoreceptors Transduce thermal energy In endothermic animals, thermoreceptors provide cues about body temperature Some invertebrates use thermoreceptors to locate endothermic prey
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Thermoreception
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Electroreceptors Used by predatory fishes to detect prey Respond to electrical stimuli
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Photoreceptors Transduce light energy Serve as the sensory receptors in eyespots and eyes
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Receptor cells Absorb energy Transduce it into electrical energy Produce receptor potentials –Depolarizations or hyperpolarizations of the membrane –Graded responses
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Sensation process Sensory receptors transmit coded signals Brain interprets signals
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Sensory adaptation Decrease in frequency of action potentials in a sensory neuron Occurs even when the stimulus is maintained Decreases response to the stimulus
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Mechanoreceptors Touch Pressure Gravity Stretch Movement
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Mechanoreceptors are activated when they change shape as a result of being mechanically pushed or pulled
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Tactile receptors Found in the skin Respond to mechanical displacement of hairs Respond to displacement of the receptor cells
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Nociceptors Pain receptors Free nerve endings of certain sensory neurons –Strong tactile stimuli –Temperature extremes –Certain chemicals
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Proprioceptors Enable the animal to perceive orientation of the body and positions of its parts –Muscle spindles –Golgi tendon organs –Joint receptors
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Proprioceptors
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Statocysts Gravity receptors Found in many invertebrates
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Statocysts
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Vertebrate hair cells Detect movement Found in –Lateral line of fishes –Vestibular apparatus –Semicircular canals –Cochlea
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Vertebrate hair cells Single kinocilium –True cilium Stereocilia –Microvilli –Contain actin filaments
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Lateral line organs Supplement vision in fish and some amphibians Inform the animal of moving objects or objects in its path
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Lateral line organ
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Vertebrate inner ear Labyrinth of fluid-filled chambers Canals that help maintain equilibrium
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Vestibular apparatus Upper part of the labyrinth Saccule Utricle Semicircular canals
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Human ear
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Otoliths Stimulate hair cells that send signals to the brain Enable the animal to perceive the direction of gravity
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Saccule and utricle Change position when the head is tilted Change position when the body is moving in a straight line Semicircular canals Inform the brain about turning movements
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Inner ear
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Cristae Clumps of hair cells Located within each bulblike enlargement Stimulated by movements of the endolymph –Fluid that fills each canal
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Organ of Corti Found within the cochlea Contains auditory receptors
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Path taken by sound waves Sound waves pass through the external auditory canal Tympanic membrane (eardrum) vibrates Ear bones transmit and amplify the vibrations through the middle ear
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Vibrations pass through the oval window to fluid within the vestibular duct Pressure waves press on the membranes that separate the three ducts of the cochlea Bulging of the round window serves as a pressure escape valve
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Pressure waves cause movements of the basilar membrane Movements stimulate the hair cells of the organ of Corti by rubbing them against the overlying tectorial membrane
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Neural impulses Initiated in the dendrites of neurons that lie at the base of each hair cell Transmitted by the cochlear nerve to the brain
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Chemoreceptors for taste and smell Taste receptor cells –Specialized epithelial cells in taste buds Olfactory epithelium –Specialized olfactory cells –Axons that extend to the brain
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Olfactory epithelium
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Taste and smell process Molecule binds with a receptor –Taste receptor cell –Olfactory receptor cell Signal transduction process involving a G protein is initiated
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Eyespots (ocelli) Found in cnidarians and flatworms Detect light Do not form images
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Eyespots
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Compound eye of insects and crustaceans Visual units called ommatidia –Collectively produce a mosaic image –Transparent lens –Crystalline cone –Focuses light onto retinular receptor cells
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Human eye structures and functions Light enters through the cornea Light is focused by the lens Image is produced on the retina Iris regulates the amount of light
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Human eye
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Photoreceptor cells in the retina Rods –Function in dim light –Black and white images Cones –Function in bright light –Color vision
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Bipolar cells Send signals to ganglion cells
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Lateral interneurons Integrate information Horizontal cells –Receive signals from the rods and cones –Send signals to bipolar cells
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Amacrine cells –Receive signals from bipolar cells –Send signals back to bipolar cells and to ganglion cells
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Neural pathway in the retina
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Human vision process Light strikes the photopigment rhodopsin in the rod cells Retinal portion changes shape Initiates a signal transduction process that involves transducin
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception G protein activates an esterase that hydrolyzes cGMP Reduces cGMP concentration Ion channels close Membrane becomes hyperpolarized
Copyright © 2005 Brooks/Cole — Thomson Learning Biology, Seventh EditionCHAPTER 41 Sensory Perception Rod cells release less glutamate Fewer signals are transmitted Bipolar cells become depolarized Bipolar cells release neurotransmitter that stimulates ganglion cells