Chapter 10: Physiology

> Pathological pain chronic pain also called nevropathic pain EX: Diabetic neuropathy. developg as a result of BIS. > Olfactong System Smell and taste are forms of chemoreception Olfaction allows us to discriminate among milions of different odors ortacting bulb extension of the forebrain that receives input from the primang Olfactong neuron's Hunan olfactory system congress of (primars) > olfactong epithelin: lines the nasal cavity Altactong sensong-nenmansy sensorg neurons embedded in the offertong epitheliom > off acting pere crimal nerve #1, cames info to Olfactory bulb > Olfactong bulb located on the underside of the frontal lobe Olfactiong tract bypasses the thalamu's (scansong olfactory dors of go to thrices fist) altuctrong cortex in close proximity 7 to amigos dala and huppocampus →olfactong sensong numons home short lives, sout a meriths →Stem cells found in basal layer of of actong epitheliom Olfactong neuron axons (cranial nere#1) cam-es info olfactong bulb →olfactong epitheliom lies high within the nasal cavity, (Secondang neur) DRDER OF SMELL OUPkaary neusons Cranial nerve olfactong bulo olfactory tract) Olfactong cortex Limbic Limbic system surface of epithelium lined & cllia that is embedded into alager of mucus Mucus produced by Olfactong (Bowman's) glands Odorant molecules most dissolve and penetrare muens before binding to olfactong receptor. cach Ofactory receptor sensitive to for smells only. OHactory receptors activate Golf protein which ↑ CAMP, which opens camp chamels dapolariangcell Secondary and higher order nurrmy project from the olfactong bulleolfactiong track Otactong cortex > There is a strong link between smells and emotions because olfactory is close in proximity to the limbic system. VND known to be involved in behavioral responses to sex pheromones →Humans do have a VNO TASTE (Gussation (losely linked to olfaction 5 taste sensations Sreet vmami (Sarory)-lasse assovatel amino acid glutamatel drucleotides bitter sowe (acid) triggered by prescence of H sally triggered by prescence of Nat →receptors of taste located in taste buds olustured together on the surface of the tounee 1 taste bud = 50-150 taste receptor colle+ (Suprerit has al cells) taste buds (composed of tacte cells) found on dorsal surface of the tounge tacte cells fond ontaste buds. →yasto wids have microvill taste pores small openings on the toronger that allon fond to come into codach witaste receptors. Typel Typell, TYPOM. cells (Support) Typel-ghal-like SUPPORT CELLS (receptor ) Typell-respond to syveel, bitter, & umami sensationt > Have G-coupled protein receptors preceptors activate G-protein calle Gustavcen Gustudein activates signal transduction pathways Some pethrenys release cut others open charmets and allow Catt to come in cell. Cast initates ATP release 7ATP leaves typell cells through channel protein CALIPII ATP acts as parack the signal Presynaptic) Typell respond to sour to stes ( 1H" (Sour taste signal) = Change in PH Ht depolanzation results in (Seretanin release 7Serotonin cxaites priming sensong neuron Specite hunger Chaving for a partideler Substance lack of nutrient = craving for substance Ex Salt appetite lack of Nat in body THE EAR HEARING 2 distinct functions the ear is specialized to sonse Hearing & Fauiubrium vestibular complex (in mmear ear) - primang sensor for equilionem rest of ear heanng External car hade up of finna (eat) and auditong canal (car cannal) end of car canal is sealed by car drum (tymemi mimba Eardrum seperates Duter ear and middle ear middle car. air-filled v has & bones HAS-MIS -Haremer (mallene) Anvil (Incus) Stirrup (Stapes) hammer ondattached to eardru stomp end attached to oval midow connects to pharynx through Ectuchian tube inner ear fluid-filled Has 2 major Sensory structures Vestibular apparatus semicircular (responsible for eauльтим Has cochlea which contains fluid looks like a shall basilar membrane seperates Bochla has hairs val vrindava (and round vwindow) Seperate middle ear troom tmer otitis media-middle ear infection Heaning your perception of the energy carried by sound waves, which are pressure nuoves wipeaks & valleys *nich-frequency (Hertz) amplitude-intensty (deubels) Pitch of a sound depends on the frequmug of sound invesi, measured in hertz (Ha) Loudness our interpretation of sound intensity depends on intensity of a sound ware for amplitude, measured in decibels (dB) sounds of gå decibels of more can damage hearing receptors of TRANGDOCTIONS REONIRED FOR HEARING (5STERS) sound waves hit eardrum and became vibrations 2 Vilerations at oral window (from middle for) create waves in the cochlea. ③ movement of cochlear duct openscloses ion channels on hair cell membranes creating clectical signals. ④electical signals atterneurotransmitter release 5 nemotransmittersindeng mitrales action potentials that travel through cochlear barve (CNPs) to the brain THE COCHIER transduction of wave energy into acnon potential takes place in the inner ear (уст) Cochler made Tof 3 Ploid-filled tubes vestilbular duct Ovestibular duct (Scala vesnbul) @cochlear duct (Scala media) organ of corti tympanic cochlear Helicottema (V&T Xonnected! tympanic duct (Scala tumpani) Vestibular and tympane ducts are continuesit each other and they connect at the tip of the cochlea, helicotrema endolymph fluid in cochlear duct that resembles ICF; (↑kt, Nat) Perilymph fluid in vestibular and impanic duct that ion composition resembles plasma Atmik peritemph, plasma, both start IP) つ organ of corts in the cochlear duet, composed of 4 rows of hair cell receptors + Support cells (Sits on basilar membrane Partially Covered by tectonal membrane both flexible tissimes that move in response to Huid wares passing through the vestibular duct Waves bend hair cells transuchen m hair cals apical surface of each hair ce has stereocilig tir-links Stereocitia attach to each other by protein bideges called ' When cilla bends is links pop more channels open, ications(kt and cat) enter the cell Cel depolances excitation (tip links actas like little springs Connected to gates that open clove jon channels) If hair cells bend in opp direction, ion channels close, cell hyperpolances, song nsory neuson signaling decreases 3 properties of sound wives used for disenomination location-processed by both ears and brain Pitch loudness processed by cochlea Coding for pitch is a function of the barilar membrane Dasilar membrane bas vanable scositionby to soved nave frequency along its length. sptf names Plexiblwder (thicker) thinher frea vency low frecvencies displace the distal end. High frequences dreplace proximal end (hear Basilar membrany Pitch aval round undo frequency of sound nares determines the displacement of the basilar membranes determines whot part will vibrate whatever part vibrates creates a code that the brain translates as Information about the pitch of a sound. Loudness is coded by the ear the same way signal strength is coded in somatic receptors louder noise more rapidly action potentials fire in the sensong neuron The brain localizes sound by using timing differences.. Soond directly in front of someone reaches ears at the same time Sound coming from right reaches car first Sound coming from rett reaches car first Hearing Loss 3types conductive >sounds cannot betransmitted esther through external/midok zar scousestexcess Carmax -fluid in middle ear from infection titink) Sounds cannot be conductel! Central results trom damage to nertal pathways between ear and cerebral cortex or from damage to cortell suchos might occur from astuce most common in old ↓ People sensorineura zarises from damage to the structures of the immer ear Including death of harg cells rit LOUD COUNDS Loss of hair cells is. -diseases/trauma hat Impede vibration to s middle ear bones Tx-microsurgical techniques In which bones of middle ear Can be reconstructed *Problem is in middle ear UNCOMMON Irreversible IX HA, cochlear implants prain 90Nof bearing loss in ald ppl Is this typo Sensormeurall *Problem is in immer far TEQUILIBRIUM state of balance Has 2 components dynamic component & static component dynamic tells us about our movement through space tell us if our head is & in its normal uinght position static sensory and visual information play key role in equilibrium Sense of equillonom is mediated by hair cells isning the fruid-filled vestibular apparatus of the inner ear Gravity and acceleration moves Sterocilia (rather that sound hands ilke in cochlear b Vestibular hair cells have a single long cillum, kinociliom 3 semicircular canals monitor rotational celestion Hernuantal cand monitors rotations as the head turns left/right ; such as when shaking mo pastemor canal senses the tipt of the head burward right or weit shoulder, such as when you do a cartwheel supernor canal-sensitive to forcard and hack ropilatony such as nodding your head) front to back (modding "yes" for doing a summersault At the end of cach canal there is an enlarged chamber, ampulla ampula contains crista (Sensory structure) onsta has hair cells god gelatinous mass, the cupula curulla extends from floor to ceiling of ampula, closing it off. How is pration sensed? in the ampullae, drag of endolymph beads the cupuly and its hair cells in the direction opposite to the direction In which the head is tuming head tuins right bt = tupund and hair cilis more to the left 2'like a head turns left Cupula and hau eilig move to the right Paintbrush Otolith organs sense Whear acceleration and stead positioν 2 otolith organs Utricle & Saculo Sense linear forces. Their Sensory Structures called maculae, consist of hair sells and gelatinous mass known as otholith membrane, calcium carbonate and protein particles, otoliths. →Hair cilia is embedded in Otolith mambrant otoliths bink to matrix proteins on cuiface membrane • Otoliths are crystals that more in response to gravitation forces! →maculae are hon antal when head is upnght →if head tips back, gravity displaces otoliths, and the hair cells activate or decelaration thead tilt maculae of vtricle sense find acceleration o opposit macular of saculae are oriented vertically when the hand is grect which makes Them sonsitive to verrical forces (such as dropping from elevator) cerebellum primany site for equilibrivon processing VISION process big which liget reflected from objects in our environment is translated into a mental image STERS light enters eye; lens focuses light on retina 2 Photoreceptors of retina transduce light→electical signal Neural Pathways from retina to brain process electrical signals visual wrages. comen-ruml-lens-retina neural pathways optic nerve optic chiasmorthe tract laterale maculate sugicortex body (thalamus) Coccipital love) Consensual reflex-efferent nemens constrict the pupils in both eyes visual cors ex is in the acceptal 106 Photoreceptors control amount of 119m hitting the retina.. And Pupils! in bright light- pupils now (parasympathetic) pupillary sphincter muscles constict in dim light Pupils widen (sumpathetic) - dilator muscles contract pupils create a depth of field' Shallow depin of wew Folldean of view Full depth of new is created by constricting the puml (or the diaphgram in a camera) In this way, a greater depth of the image is focused on the reting light passing the eye is refracted trices when it resses the comen (2/3 occurs in the corca) ② when a passes the lens ('13 occurs in the lens) lens can change the shape to focus light angle of refraction how much the 119m rays bend) infiuenced by 2 FACTORS difference in density of the I media ②ange at which light rays meet the surface of the pediva into which its Passing. Parallel light rays perpendicular lens = 1 bending when light passer (dirergong lens) paralle light rays concavellens refract vrider ↓ refract wide (Conyerong parallel ligynt rays convex lent = i gat rays converged ind meet at a focal poust!. lens) light pays converge come together at afrual paint focal lenght-dicimnice from cemer of a lens to the focal point focal distance) Focal length is fixed for focal lenght to change-shape of leas has to chang →Focal point most fali on retina to be in taus! Jany object 2011 from eye will be intocus when lens is fiat object closer thah 20fith focce point is behind reina in-focus!! lens must become more rounded to be in focus Accommodation praess by which eye adjust's shape of lens to keep objects in focus Near print of gecomodation closest distance at which it can focus on Objecta accommodation refter Ciliary musele controls changes in lens shape lens is attached to cillang muscle by inelastic ligaments (ZONULES) Olllary muscle relaxed-ligaments pull & fratten lens (atres) olllary muscle contracts - ligaments release tension, lens becomes more thanded. Parasympathichic contracts ciliangmuscle (presbyopia) presbyopia 1085 of abints to accommodate chimnotaccommodate- myopia rear-sightedness" focal point falls in front of retin VISION DISORDERS hyperoper far Cignterdicess & focal point falls behind reting astigmatism-labnormally shaped corned resulting in distorted images Frequency range Fim Spectrum visible lights in humans are limited to electromagnetic enerry I haves that have a frequencry and a wavelength of 400-750 nanometers cycles/sec of 4.0-7.5x10 cycles sec PHOTOTRANSDUCTION Process bly which animale convert light energy into electrical signals 5 types of neurons in the retina: Photoreceptors (odstcones) Bipolar cells ganglioncells amacrime cells honzontal cells + GLIAL CELLS (ASTROLYTES) and Support cell (MILLER CELL photoreceptors negons that covert light enering to electrical signals 2 main tupes rods & cones Pigment epitheliom absorbs excess light, preventing distorting images forea and macula surrounding forea) are the areas of most acute vision There is neurons/wood vessels in foved that heck lighth reception form the visual field *Image falling m the retina is Upside dim Visual brain pricessing later reverses the image agam- OPTIC DISK BLIND SPOTI optic disk has photoreceptors so Images projected onto this region cannot be seen! optic disc is also the region where optic reme and blood vessels leone the eye D Rods Cores -cone shaped -lowlight (nigh vision) -color, clanity objects seen in black/white rather than -8 harpfouns -In friver There is IS NO RODS IN FOVEA In color -HIGH ACUITY (Keenes) cylindrar shape -Outnumber cones 201 EVEρη Pemphenol nism 2 Types of Photoreceptors have the same structure. Liant transducho Takes Place in Segment ① an auter segment whose fir touches the pigment epitheliun inner separent, that contains the cell nucleus and organelles for Amp Potem snyathens. basal segment with a Synapte terminal that relanses glutamater into bipurcells In Outer segments, The cell membrane has folds that form "disc-like" layers Rhodorsin-visual pigment in ROBS 3 visual Pigments in CONES! Red/Careen Blve Visual pigments are bound to disk membranes in outer Segments of photoreceptors color-Bundness condition in which a person inhents, detect in one or more of the 3 types of cores, and has difficulty distinguishing certain colors. RED-GREEN color blondness is the best troude telling red green apart) The perceived color of an object depends on the color(s) of light that the object REFLECTS In darkness retine bindstopsm when activated by light Bleaching when activated rehnallenger binds to from propment in process known as bleaching opsth 15 released Rhodopsin is composed of 2 molecules: opsin of retinal! PHOTOTRANSDUTION IN RODS Darkness Phase Thodopean Is Inachre (UFP) CGMP 15 CNG and kt channels open 1 (Tets Nel Cat (rets koul) rod stays deplanted at 40 mv instead of usual-70m) Voltage gated Ca's channels tre OPEN ↓ tonic (continuous) release Glutamate Onto Bipolar cells RECOVERY PHASE Chidorsin is activated (ON) Francducun cascade VeGmp EXPOSURE TO LIGHT closes CNG channels (@more influx of casted Nat ktefflux continues, causes hyperpolarization (tomu) glutamate release ontol Bipolar cell 6 decreases BRIGITT LIGHT closes all as channels and STOPS neurotransmitter release 100% retinal diftuses out of the rod and is transpared into pigment epithelium. - reverts to its inactive form before moung back the into rod and being reunited with opsin →Retinal REBINDS TO OPSIN RADS contain & maar types of cation channels →ING channels let Nat and Catenter rod cylic nucleotide-galed) →kt channels-det kt leak out of rod →voltage gated Cat channel Tegulatineurotransmitter release Signal processing in the retina is an excellent example of convergence because as many as 15-45 phutoreceptors converge on one bipolar neuron (focal point) Convergence is minimal in the oven) (thats way it has of clanty) Greatest at outer edges of the renna Honzontal cells-Synapse I photoreceptors and bipolar cells to mediate lateral inhibition in the retiия Lateral inhibition enhances stimulus location and contract Amnacrine cells-modulate information flowing betrreen bipolar ganglion cells- 2 types of BIPOLAR CELUS LIGHT ON, Light of f LIGHT ON (ON BIPOLAR cens) - activated in light when glutamate secretion or posates by photoreceptore decreases. in darkness, ON bipolar cells are inhibited by glutamate release OFF bipolar cells-exuted by glutamate release in the dark In light t'less glutarmare, off cells are inhibited In lignt-on receptors actuated OFF receptors inhibit GANGLION CELLS Buolar cells synapse I ganglion cells (lie on surface of retina) →Each ganglion all receives information from a particular area of the retina Visual receptive field- areas in the retina Receptive frelds are roughly circular have centers (yellow) and outer surrounds (gray) this organization allows ganglion cells to use contrast between the its surround to interpret visual information center and its sm →Strong contrast strong exutatong response, or strong inhilatory response →Weak contrast intermediate response ganglion cells in retina mcells (magno cellular) BG Sensitive to morement Pcells (pomocellular firedelalte fum 2 tupes of ganglion receptor fields. Orl-center/off-surround field off-comer/ on-surround Field In an on-center/off surmurd gang lon cell responds most strongly when light is brightest in the center of the fitlul If light is unghtest in off-surround region of the field, the un-center/ off surround field ganglion cell is inhibited and stops firin's action potentials →The reverze happens off-center/on-surround fields Type of gangnon.cells in retina" m cells predominant make up 80% Peells •Im cells (Large Magnocellular ganglion cells)-sensitive to into about movement ►P cells (smaller parvocelular)-more sensitive to signals that pertain to form aand fine detail Subtype ganglion cell (MELANOPS IN FETI) acts as a Photorecer tor to relay information about light cycles to surrachiasmatic nucleus which Contros circadian rhythms Visual acuity is greatest when goinguon cells hare few photorecer fors in its visual freld At the op of the some the fimis from each eyo cross to the other side of the brain for processing Binocular zone thhere I AR sidus of each eye's visual field-oreftan "Central portion of the visual field" (see object's in 3D brain processes ilk diff views into a 3Dobject- → monocular zone Visual field of only one eye Lobjects seen in 20 only Sense of depty perception (whether one Obreet is in frontfor behind of the other) depends on Binocular zone). Binocular zone-3D Monouilar zove-20. fibers that project to ridbrain from the optic chiasm participate in Control of eye movement or coordinate & somatosensory and auditong information for balance and movement most axons project to large gemulate body of thalamus. were optic fibers Synapse onto heurons leaders to the visual cortex in the ouirital lobe. large geniculate body. is organized in layers that Correspond to different Parts of the viral field, which means into from adjacent objects is processed together. ↓ Topographical organization maintained in visualcortes has layers each portion of visual field-Processes into further by form, color, movement.