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CSCI A110: Intro to Computers and Computing
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This 8 page Class Notes was uploaded by De Vs on Wednesday February 25, 2015. The Class Notes belongs to BIL360 at University of Miami taught by Dr. DuBois in Spring2014. Since its upload, it has received 106 views.
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Date Created: 02/25/15
Chapter 14 Sensory Processes Sensitivity ability to distinguish among stimuli with diff Intensity Speci city ability to distinguish among diff types of stimuli Sensory Receptor Cell transduce stimulus energy into an electrical signal receptor potential and encode info about a stimulus via APs to the CNS Stimulus form of electrical energy that a sensory receptor cell responds to Sense Organ structures that are specialized for reception of particular stimuli Sensory System sense organs and all associated processing areas Sensory Transduction when sensory receptor cell coverts stimulus energy into an electrical signal lonotropic Transduction stimulus is received and transduced by same receptor molecule Na centry into the cell causes depolarization touch balance sound Metabotropic Transduction sensory receptor molecule activates metabotropic cascade by activating G protein that activates effecetor molecules that alters conc of second messenger vision olfaction taste Exteroceptor respond to stimuli outside body lnteroceptor respond to internal stimuli Principle Of Labelled Lines sensory modality quality of sensation associated with a stimulus depends solely on which receptor cells are stimulated not how they are stimulated Mechanoreceptors respond to diff types of mechanical stimuli Ouch pressure equilibrium hea ng Touch Sensillum mini sense organ Hollow with sensory neuron endings when the bristles moves it opens stretch activated channels that allow cations to ow through The net inward current produces a receptor potential Receptor Potential primary electrical response of a sensory receptor cell to stimulation In most the receptor potential is a depolarization If suprathreshold the receptor potential depolarizes the sensory neuron enough to make AP that progoate to the CNS Dorsal Root Ganglion sensory neurons Touch receptor cells in mammals are epithelia cells with the distal endings of neurons that have cell bodies in the dorsal root ganglia next to spinal cord They send Sensory Adaptation frq of AP over time decreases to a continuous stimulus Tonic Response slowly adapting Decrease slowly in frq and continue as long as stimulus is present merkel discs and ruf ni endings Phasic Response rapidly adapting Single changes in touch or pressure Gives a burst of AP as stimulus is applied but stops during a maintained stimulus Proprioceptor internal mechanoreceptors that measure tension stress limb position posture Statocyst organ for orientation with respect to gravity Has grains of sand or CaCo3 that singks and stimulates receptor cells by bending the cilia Tympanal Organ thin cuticular eardrum that is displaced by sound waves Mechanosensory cells are attached and stimulated by its movement They are on the thorax abdomen legs etc Hair Cell sensory mechanoreceptor cells for acoustic lateralis system epithelial cell with microvilli at apical side No Aps they release neurotransmitter substance onto afferent neurons that conduct AP to the CNS Hair Bundle tufts of hair cells Stereocilia individual microvilli Vestibular Organs sense acceleration and balance Adjacent to auditory organs in the inner ear that use hair cells The hair cells project into uid lled chambers Semicircular Canals there are three canals in each vestibular organ Detect acceleration of the head and body Otolith Organs there are 2 called sacculus and utriculus for linear movement and acceleration External Ear distal to eardrum Middle Ear air lled Middle ear ossicles transfer sound energy from air to liquid of inner ear they increase pressure to transfer sound Inner Ear liquid lled Cochlea coiled tube with uid chambers Basilar Membrane multicellular membrane separating cochlea into upper and lower chamber As oval window moves it moves uid in cochlea that vibrates the basilar membrane and stimulates auditory hair cells It is narrow and thick at the base near oval window and gets wide and thinner at the apex Organ Of Corti region of cochlea with hair cells that get stimulated by basilar membrane movement Inner And Outer Hair Cells three rows of outer and one row of inner lnner sends most of the auditory signals to the brain Outer change in length and respond to sounds Afferent axons get input from inner hair cells and efferent axons from outer Depolarization makes hair cell shorten and hyperpolarization makes it lengthen 1 Differentiate between sensitivity speci city of sensory receptors 0 Sensitivity is the ability to differentiate btwn diff strengths of stimuli and speci city is for diff types of stimuli 2 In what ways are sensory receptor cells classi ed Sensory modality nature of stimulus 0 Form of stimulus energy electromagnetic chemical Mechanism of transduction ionometabotrophic Location of source of stimulus energy exterointeroreceptors What is the general mechanism by which receptor cells transduce and encode sensory information Describe each process What is the principle of labeled lines 0 Receptor molecules initiate transduction of a stimulus energy to make an electrical response called receptor potential by depolarization which leads to AP carried to CNS The transduction can nbe ionometabotropic The sensory modality depends on which receptor cells are stimulated not how they are stimulated Describe the general anatomy and function of mechanoreceptortouch sensilla in insects Describe the process of receptor potential generation and how the strength of a stimulus is encoded in a train of action potentials The bristle sensillum extends from the cuticle it is attached to a mechanoreceptor dendrite of a bipolar neuron which is surrounded by an epithelial cell The movement of the bristle opens stretch gated ion channels allowing inward current of ions 0 The receptor potential depolarizes the sensory neuron if suprathreshold to generate AP to CNS What is the structureidentity of mechanoreceptor cells in mammalian skin Merkel discs and meissner corpuscles are beneath epidermis pacinian corpuscles and ruffini endings are deeper Endings of neurons with cell bodies in dorsal root ganglia next to spinal cord What is sensory adaptation Compare the tonic and phasic receptors What information is encoded by these types of receptors Sensory adaptationthe frq of AP in response to a constant stimulus will decrease over time Tonic responses decrease over time and are slowly adapting they continue as long as stimulus is present Phasic responses adapt rapidly and signal changes in touchpressure to give a burst of APs but stops during a maintained stimulus Describe how a statocyst allows a jelly sh to orient with respect to gravity Statocyst has grains of sand that sinks down and stimulates receptor cells by bending their cila It gives info to tabout orientation relative to gravity What is sound Describe how sound stimulates the tympanal organ of a noctuid moth How does a moth use sensory information from its quotearquot to respond in an adaptive way to predatory bats Sound is waves of pressure of air or water that propagate away from a vibrating source 0 The auditory organ in insects is the tympanal organ that has a thin cuticular tympanum that is displaced by sound waves Mechanosensory cells are attached to the tympanum and stimulated by its movement Noctuid moths have tympanal organs with only two neurons lts range is ultrasonic at matches frq of bats to hear when they are coming It will y erratically or dive to the ground A1 cell response Describe the structure of a hair cell How does a hair cell transduce mechanical force into action potentials Hair cells are sensory mechanoreceptor cells in vertebrates including vestibular organs balance 0 Hair cells are epithelial cells that have a tuft of microvilli at apical end called hair bundle Individual microvilli are stereocilia Hair cells do not make APs they release neurotransmitters onto afferent neurons that send APs to the CNS 0 Have stereocillia Form synapses with neurons depolarized by movement of hairs Bending of stereocilia gets transduced into a receptor potential 0 The movement away from the neighboring hair creates a change in membrane potential It is directionally sensitive depending on if it moves away or towards 10How do the semicircular canals allow vertebrate animals to sense acceleration and orientation of the head Note their orientation uid and hair cells 0 The canals are oriented at right angles to each other ate detect movement on all axes in space The base of each canal has an ampulla region that has a cluster of hair cells in a structure called crista ampullaris Acceleration of the head causes uid in the ampulla to sosh against hair bundles Fluid movement pushes against the crista ampullaris and de ects bundles to openclose mechanoreceptive channels Movement in any plane moves uid to one side and hair cells get depolarizedhyperpolarized and carry info to the CNS 11Describe the sensation of hearing in the mammalian ear Include the path of sound from the external ear to internal ear including the eardrum ossicles oval window and cochlea What features of the basilar membrane contribute to the speci city of human hearing to particular sound frequencies Describe the anatomy of the cochlea including the three uid lled chambers basilar membrane and organ of Corti How does movement of the basilar membrane in uence hair cells to send signals to the brain via afferent neurons 0 Sound waves enter air in external ear three ossicles of the middle ear transfer the vibration to the oval window of the inner ear 0 As oval window moves it creates uid movement in the cochlea Sterocilia of hair cells get pushed against tectorial membrane as basilar membrane moves up and down This causes hair bundles to get displaced Basilar membrane displacement bends the seterocilia of hair cells against the tectorial membrane that transduces sound vibration into electrical signals of the hair cells 12How do animals such as owls process sound information at their two ears to localize the location of a sound source Owls can localize sounds horizontally and vertically and use time diff of 10us Ears are asymmetrical Vertebrates use time and intensity differences to determine left and right origin of sounds PART TWO Chemoreception sensory response to a chemical stimulus tasteolfaction Taste gustatory sense Liquid stimuli taste sensillum located on tarsus leg antennae or proboscis mouth Taste receptor cells are within sensila It has 24 chemoreceptor cell dendrites and a mechanoreceptor The tip has holes where water and taste molecule enter taste bud groups of taste cells on tongue or back of mouth in mammals papillae clusters of taste buds olfaction the sense of smell Airborne stimuli olfactory sensillum on the antennae Instead of a single or few pores like the taste the olfactory has lots of pores on the bristle vertebrate olfactory epithelium in nasal cavity Each olfactory receptor cell is a bipolar neuron with a cell body in the olfactory epithelium with cilia that contain intramembrane receptor proteins A dendrite extends to the surface into the layer of mucus The receptor cells have unmyelinated axons that extend to the olfactory bulb in the brain life span of 60 days Binding of an odorant to an OR protein initiates the pathway glomerulus where the axon of each receptor cell ends All cells expressing same receptor molecule end in the same two glomeruli so receptor types are segregated olfactory bulb olfactory receptor cells send axons to bulb in the CNS vomeronasal organ 2nCI olfactory system under the olfactory epithelium on each side of the nose It detects pheromones and chemical signals Axons go to a different olfactory bulb photoreception response of a sensory cell to light Hyperpoarize in response to light Photoreceptor cells have increased surface areas for more light sensitivity camera eye formed independently Makes an inverted image that is ipped on the back of the retina The info travels to the brain via optic nerve compound eye evolved from pigment cup Many pigment cups grouped together to make compound eye Formed by ommatidium that makes mosaic image Insects and arthropods Very sensitive to movement Photopigment a pigment that absorbs light made of protein and cromophore mostly rhosopsin Chromophore nonpeptide organic molecule When it absorbs a photon of light it makes a transduction cascade Retinal the chromophore of animal photoreceptors that is bound to opsin Undergoes photochemical change when light hits it all trans shape Opsin integral membrane protein associated with opsin When light hits retinal the opsin has a conformational change too Rhodopsin a photopigment of retinal and opsin Retina the photoreceptor containing layer at the back of the eye Light gets refracted btwn the air and cornea extension of brain tissue Performs the rst stage of vision It is inverted with photoreceptors in the outer layer farthest form the light Contains rod and cone receptor cells Since its inverted the optic nerve faces the lens and axons exit thru the retina at the optic disc making a blind spot Fovea high conc region of photoreceptors in humans its cones Blind Spot region on the retina where you cant see Rod photoreceptor in retina More sensitive long thin cells low light sensitive to dim light Multiple rods connect to bipolar cell The outer segment of rodscones have lamellae with photopigment molecules In rods they are discs Cone used in brighter light for color vision Higher acuity vision Shorter Nocturnal animals have all rods and diurnal animals have mostly cones In cones the lamellae are invaginations of the outermembrane Dark Current made by ow of Na into the cell Dark current must be counteracted by the use of ATP to pump Na out of the cell This current keeps the rod relatively depolarized In response to light the dark current decrease and makes a hyperpolarizing receptor potential Glutamate brains main excitatory neurotransmitter in the dark it regulates Ca Network of neurons in the retina Bipolar Cells receive input from photoreceptors at eh outer plexiform layer Horizontal Cells tangentially connect diff regions of outer plexiform layer Amacrine Cells mediate tangential interconnections in the inner plexiform layer Ganglion Cells provide sensory output of retina with axons that form the optic nerve that extends to brain Receptive Field the area of the retina or visual eld within which the membrane potential of that neuron can by in uenced by light For ganglion cells the eld is larger than rodscones OnCenter cell ganglion cell receptive eld to the left It is maximally stimulated when the entire center of its receptive eld is illuminated It is inhibited when the surrounding but not the center is illuminated OffCenter cell cell on the right that is inhibited by light in its center and excited by light in its surround Mono Di TriTetrachromate mono have one receptor whales and seals no color di have two mammals and humans and primates of three birds and reptiles have four receptors NonSpectral Color purple not in visible light Lateral Pathways horizontal and amacrine cells make the surround of a ganglions receptive eld Straight through pathways receptor bipolar ganglion Make center of ganglions receptive eld What is the difference between taste and olfaction Describe the general anatomy and function of taste receptors in insects 4 chemosensory neurons sensitive to speci c chemicals 0 Each chemoreceptor cell is sensitive to certain chemical ligands Water sugar salt alkaloids Increasing conc makes the cells have higher frq of AP Describe the general anatomy of a taste bud in mammals What are papillae What are the ve basic taste sensations What triggers each and how are the different tastes transduced Epithelial sensory cells 0 Type I II III taste cells type IV makes new taste cells 0 5 categories of taste salt sweet bitter sour umami MSGaspartate soy sauce cheese meats saltysour exhibit ionotropic transduction sweetumamibitter transduced by G protein coupled receptors Exhibit metabotropic transduction salty when Na conc increases in mouth the salt receptor cell depolarizes sour mediated by a channel GPCRs Describe the general anatomy and function of an olfactory receptor in insects What is the adaptive function of odor generalist cells vs odor specialist cells Odor generalists detect a wide variety of odors Odor specialists detect pheromones metabolites released outside the body What is the process of olfaction in mammals Describe the general anatomy of vertebrate olfactory receptors What are glomeruli How is an odorant chemical detected and transduced to an action potential What is the vomeronasal organ Receptors in the nose are specialized for certain odors Receptors are connected by glomeruli depending which glomeruli is stimulated Each olfactory receptor is a bipolar cell will a cell body in olfactory epithelium Each has a dendrite that sticks out of the mucous with lots of silia on it Olfactory receptor proteins are GCPRS that simulate cAMP Epithelial cells around the olfactory cells There is more overlap in humans btwn what detects pheromones Neuronal receptor cella have cilia with receptor proteins Each receptor cell expresses the gene for one membrane receptor protein and all the receptor neurons that express that same protein synapse in the same glomerulus of the olfactory bulb The vomeronasal organ senses pheromones and their sensory cells are micovillar not ciliary that do BPCR are stimulate lP3 and DAG How does the form of an animal39s eye re ect its visual needs What is the difference between a camera eye and a compound eye What animal groups possess each 0 Camera eye vertebates Compound eye insects Has ommotidia 7 Describe the structure of the animal photopigment rhodopsin and how it changes in response to light 0 Made of retinal and opsin Retinal exists in two isomers cis and trans Light triggers a change from cis to trans Opsin has alpha helix regions Rhodopsin is found in the outer segments of rods and cones When rhodopsin absorbs light it acts via aG protein to decrease cGMP conc in cytoplasm which closes the cGMP gated Na channels that keep the photoreceptor depolarized in the dark Light induced closing of these channels hyperpolarizes photorecptors After activation the rhodopsin is deactivated and returned to the cis conformation 8 What are the photoreceptors of the retina What types of vision are enabled by each type of photoreceptor How do they differ in morphology Rods more sensitive dim light Cones are brighter light for color vision 9 Describe the process of phototransduction in a photoreceptor Include the G proteincoupled signaling cascade and how this in uences membrane potential What happens to membrane potential in dark conditions Light conditions How does this affect communication between photoreceptors and bipolar neurons 0 Light photon reaches rhodopsin absorbs photon retinal becomes trans trasducin G protein gets activated GMP phoshpdiesterase gets activated which breaks down cGMP and the lack of cGMP closes the channels so Na stops coming in cGMP is important for ion channels on outer membrane of photoreceptor Ligand gated channels 0 When rhodopsin is activated the cGMP conc is lowered and it dissociates from ion channels on outer cell membrane to close them Light closes channels Na is not coming in and gets hyperpolarized This pathway is why photoreceptors are so sensitive they amplify the signal can activate many proteins DARK high cGMP bound to ion channels open membrane is permeable to Na resting membrane potential is not very negative depolarized membrane potential 0 Dark current the inward movement of Na LIGHT activation of rhodopsin and G protein cascade that breaks down cGMP low cGMP ion channels close the resting membrane potential becomes more negative HYPERpolarizes In the dark calcium channels close so there is a lower ow of Ca into cell 10What are the 4 integrating neurons of the retina Describe the idea of a receptive eld What is encompassed by the receptive eld of a ganglion cell How do oncenter and off center ganglion cells contribute to the perception of contrast Photoreceptor horizontal bipolar amacrine ganglion cells to brain Receptive eld allows us to see contrast depending on ring rates in the center and surround 11Understand the basic mechanism of color vision color opponent systems provided by the different cone pigments Do all animals see color Which are most likely to see color What are some differences in color vision among animals 0 Visual system responds to patterns and contrast changes in light level and color Sessile organisms don39t need eyes Motile animals need them Pigment cup eye doesn39t form images but can detect shadows Flatworms rotifers annelids crustaceans gastropods echinoderms Simple eye design
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