Ch 10: Sensory Physiology

endocochlear potential

+80mv

TRP channels

- warm transduction - respond to painfully hot stimuli - respond to painfully hot chemicals - respond to painful mechanical stimulation

describe how taste receptors are able to detect the four primary tastes.

-A single taste bud contains 50-100 taste cells representing all 5 taste sensations (so the classic textbook pictures showing separate taste areas on the tongue are wrong). -Each taste cell has receptors on its apical surface. These are transmembrane proteins which admit the ions that give rise to the sensation of salty; -bind to the molecules that give rise to the sensations of sweet, bitter, and umami. -A single taste cell seems to be restricted to expressing only a single type of receptor (except for bitter receptors). -A stimulated taste receptor cell triggers action potentials in a nearby sensory neuron leading back to the brain. -However, a single sensory neuron can be connected to several taste cells in each of several different taste buds. -The sensation of taste — like all sensations — resides in the brain [evidence].

spinothalamic tract1

-Cold signals are transmitted along this pathway. - The first-order neuron synapses with the second order neuron in the spinal cord dorsal horn. -Warm signals are transmitted along this pathway. - Pain signals are transmitted along this pathway.

hair cells in inner ear

-Hair cells are surrounded by endolymph. - When potassium channels in hair cells open, potassium ions move into the cell, depolarizing it. -Only the inner hair cells of the cochlea function directly in sound transduction. -There are three rows of outer hair cells and one row of inner hair cells

how light is converted to electrical energy in the eye?

-Light enters the visual system through the eye and strikes the retina at the back of it. The retina is composed of specialized cells, the rods and cones, which convert light energy into neural activity. -light-sensitive pigments located on the discs in the outer segments of the rods and cones.When light strikes these pigments, they change form, causing a cascade of chemical reactions in these photoreceptors. -these reactions make the photoreceptors' membranes less permeable to certain ions, such as sodium. This change in permeability alters each photoreceptor's membrane potential and allows it to send a nerve signal to cells in the next layer of the retina.

semicicular canals

-at one end of each canal: ampulla, enlarged chamber that contains a sensory structure called a crista and hair cells -crista contains hair cells and gelatinous mass (cupula) -how rotation is sensed: head turns, bony skull and membranous labyrinth move, fluid in labyrinth doesn't move bc inertia. in ampullae: drag of endolymph bends cupu;a and hair cellls in opp direction to which head is turning -K+ opens and moves in ,depol

sounds are processed first in the cochlea

-auditory system processes sound waves -initial processing is done by cochlea -basilar membrane: codes for pitch -3 parts: scala media, scala tympani, and the scala vestibule(The stereocilia and kinocilium on the hair cells of the ampulla project into the scala vestibule)

nocioreceptor pathways

-begin with activation of neuron's free nerve endings -ion channels (TRP channels) respond to variety of stimuli and if graded potentials are large enough: action potential ex) vanilloid receptors respond to stove heat ex) chemicals that mediate inflammatory responses: K+, histamine, prostaglandin, serotonin, substance P (responsible for the transmission of a painful stimulus between first- and second-order neurons) -inflammatory pain: increased sensitivity to pain at site of tissue damage -primary sensory neurons terminate in dorsal horn of spinal cord -2 pathways: reflexive protective responses integrated at level of spinal cord and ascending pathways to cerebral cortex that become conscious sensation -deep somatic pain: pain felt deep in skeletal muscles -ischemia: muscle pain b/c of lack of adequate blood flow, reduced O2) occurs during myo infarct -visceral pain: pain in heart and other internal organs -referred pain: pain from one area spreads to another -chronic pain: long term changes in nervous system ... long term potentiation? -chronic pain is pathological, neuropathic

auditory pathways project to auditory cortex

-cochlea transfers sound waves into electrical signals, sensory neurons relay this to brian -vestibulochochlear nerve and projections into cohclear nuclei in medulla oblongata -in medulla: secondary sensory neurons project to ipsilateral and contralateral nuclei -then locallization of pathways and sound source -auditory cortex found on temporal lobe

light enters eye through cornea

-enter through cornea -modified by: amnt of light tha reaches photoreceptors is modulated by change in size of pupil and light is focused by changes in shape of the lens -human eye: 100,000 fold range of light intensity -bright sunlight: pupils constrict tp 1.5 mm by pupillary sphincter muscles -dark: dilate to 8mm my dilator muscles -pupils create a depth of field: like zooming camera, full depth of field: constrict pupil -Which of the following is true of photoreceptors in the light (relative to the dark):phosphodieterase is more active

skull protects eye

-eyes are protected by orbit: bony cavity formed by facial bones of skull -extrinsic eye muslces are skeletal muscles that attatch to the out surface of the eyeball and control eye movements -upper and lower eyelids: anterior surface of eye -lacrimal appartatus: system of glands and ducts that keeps continuous flow of tear to keep moist and free of debris -pupil: opening through which light passes into interior of eye..black spot iinside of colored ring of pigment...The amount of light that impinges on the retina is primarily regulated by the iris -pupil size varies with the contraction and relaxation of a ring of smooth pupillary muscle -iris: pigmented part of eye -eye itself: hollow sphere dividedby 2 compartments separated by lens -sympathetic nervous system, causes dilation -lens: suspended by disks called zonules that focus light... refractive power of lens can be altered to focus light -anterior chamber: filled with aqueous humor, low-protein , plasma like (secreted by ciliary endothelium), nourishes the lens and cornea -beind lens: vitreous chamber: filled with vitreous body, clear, gelatinous, keeps shape of eye -sclera: outer wall of eyeball

thermoreceptors

-free nerve endings that terminate in subcutaneous layers -cold recpetors: sensitive to temps lower than body temp -warm receptors: temps higher than body temp, above that: pain receptors -fam of cation channels called transient receptor potential channels (TRP) initiate action potential, transduction of pain or irritating stimuli

bipolar cells

-glutamate release from photoreceptors on bipolar neurons begin signal processing - light on: activated in light, glutamate secretion dec (depends on mGluR6: hyperpolarizes cell to bind glutatmate in dark) and light off bipolar cells: excited by glutamate release in dark

pain modulation

-pain can be magnified by past experiences or suppressed in dorsal horn of spinal cord -gate control theory: a delta fibers carrying sensory info about mech stimuli help block pain transmission, enhance interneurons inhibitory activity.. basically prevent pain sensation -analgesic drugs: alleviation of pain, asprin to opioids -endogenous opioids: endorphins, enkephalins(pain suppression), dynorphins

the ear

-hearing and equilibrium -external ear: pinna(physical ear) and ear canal(sealed at end by typmanic membrane or eardrum, separates external ear from middle ear) -middle air: air filled pathway that connects with phayrnx through eustachian tube -otitis media: ear infection -3 bones of middle ear: conduct sounds from external env to inner ear: malles (hammer), incus(anvil) and stapes (stirrup) -inner ear: vestibular apparatus(cochlea: contains sensory receptors for hearing) and semicircular canals -oval window and round window separate liquid filled cochlea from air filled middle ear -vestibulocochlear nerve lead from inner ear to brain -cochlea: transduction of sound waves into neural impulses

after passing through pupil

-light strikes the lens which has two convex surfaces: cornea and lens bend light rays so they focus on the retina (light sensitive lining of eye that contains photoreceptors) -optic disk:where neurons of visual pathway form the optic nerve (cranial nerve 2) and exit eye -light striking optic disk is not detected by photoreceptors? -optic nerve from retina goes to optic chiasm (indentation in the retina that contains the fovea): fibers cross to opposite side - ganglion cells from the nasal portion of the retina cross over, whereas the ganglion cells from the temporal portion of the retina remain on the same side -synapse in lateral gentricular body of thalamus: vision neurons terminate in occipital lobe at visual cortex -testing pupillary reflex, light hitting retina activates reflex, constrict pupils (consensual reflex)

vsetibular apparatus

-membranous labyrinth, interconnected fluid channels -2 sacclike organs(tell us about linear acceleration and head position): saccule(linear: up and down), utricle ...and three semicircular canals (rotational acceleration of head) -angular acceleration: hair cells in semicircular canals -The mass of the gelatinous material within the saccule and utricle is enhanced by the presence of what type of crystals: calcium carbonate -meniere's disease: excessive accumulation of endolymph

touch receptors

-most common receptor in body -found in skin and deeper regions -free nerve endings, more complex, pacinian corpuscles: respond to high frequency vibration (large), rapidly adapting phasic receptors, deep layers of skin.. superficial mechanoreceptors located in both glabrous and hairy skin. -merkel receptors: nonneural sensors in somatic senses, superficial layers of skin, slow adaptation...found in fingertips and lips -ruffini corpuscles: superficial layers of skin, slow adaptaion -meissners corpuscles: superficial layers, rapid adaptation -free nerve endings: respond to noxious stimuli, sense hair movment

nocioreceptors

-neurons with free nerve endings that resond to a variety of strong noxious stimuli that cause or have potential to cause nerve damage -found in skin, joints, muscle, bones, but not CNS -their activation initiates adatptive, protective responses -aff signals carried to CNS: 2 sensory fibers: a delta and c fibers -pain: subjective perception, individual, vary with emotional state -fast pain: sharp and localized, rapidly transmitted to CNS by myelinated c fibers (rapid warm associated with c fibers) -slow pain: dull, diffuse, carried by small unmyelinated a delta fibers -itch: comes from nocioreceptors in the skin, characteristic of rashes and other skin conditions -sensory receptors that respond to tissue-damaging stimuli or stimuli that have the potential to damage tissue? -Chemical nociceptors respond to chemical substances released by damaged tissue.

two types of pain

-nociceptive pain: common sensical pain that arises from damaged tissue -neuropathic pain: damage to nervous system

receptors are sensitive to particular forms of energy

-nonneural sensors: hair cells of ear, cells that synapse into sensory neurons -nonneural accessory structures: critical to operation of sensory systems ex) somatosensory receptors: hair on arms, sense movement in air mm above skin surface -lack free nerve endings -4 main types of receptors -chemoreceptors: respond to chemical ligands and bind to receptor, detect free hydrogen ion content of blood -mechanoreceptors: respond to mechanical energy (pressure, vibration, sound).. mechanoreceptors located in skin: Meissner's corpuscles, Pacinian corpuscles, hair follicle receptors, merkel's disks -thermoreceptors: respond to temp -phtotoreceptors: respond to light

glaucoma

-norm: aqueous humor is secreted by ciliary epithelium and flows through pupill, drains out of canal of schlemm into anterior chamber of eye -if outflow is blocked, aqueous humor is bloced, inc in intraoccular pressure: risk factor for glaucoma (degeneration of optic nerve) -leading cause of blindness worldwide - An increase in pressure within the eye due to expansion of the aqueous humor that can eventually compromise blood flow to the eye is called

lens focuses light on retina

-opitcs: physics that describes the\ behavior and properties of light -refract: when light rays pass from air to medium density, like glass of water, they bend,"refract" -angle of refraction depends on: difference in density b/t two media, angle at which light rays meet surface of medium its passing thru -concave lens: wider beam, convex lens: focus inwards to a point and converge light waves -focal point: when parallel light rays pass through a convex lens, single pt where rays converge -focal length: distance from center of lens to its focal pt -accommodation: eye adjusting shape of lens to keep objects in focus ex) rounding lens: light rays converge on retina instead of behind it and focus on object -near pt of accommodation: closest distance at which eye can focus an object -lens doesn't change shape b/c of ciliary muscleL ring of smooth muscle that surrounds it and is attached by zonules -ciliary muscle:connective tissue that connect the lens to muscles -presbyopia: reason most people wear reading glasses as they age: loss of accommodation -accommodation: In order to focus light coming from a near source onto the retina, the lens adjusts its refractive power -myopia: near sightedness, focal pt in front of retina... light, originating from a distance, is focused in front of the retina?... concave lens corrects this -hyperopia: far sightedness, focal pt behin retina..light, originating from a close-up source, is focused behind the retina... convex lens correct this -astigmatism: cornea is not a perfectly shaped dome: distorted images

processing beyond retina

-optic nerve enters brain at optic chiasm, cross to other side -binocular vision: central point of visual field, where left and right side of eye visual field overlap -monocular zone: objects that fall in visual field of only one eye -topographical organization: lateral gentriculate body organized into layer: correspond to diff parts of visual field, info from adjacent objects is processed together

hearing

-perception of sound -sound: brains interpretation of frequency, amp, duration, of sound waves that reach our ears -brain translates frequency of sound waves into pitch of sound -sound wave frequency measure in Hertz (Hz) -human range: 20-20,000 Hz -loudness: interpretation of sound intensity, influenced by sensitivity of ear -amplitude: intensity of sound wave -intensity measured in decibels

receptive field

-region of skin that, when activated, will result in the change of activity within a particular afferent neuron -somatic sensory and visual neurons activated by stimuli that fall w/in this specific area --primary sensory neuron: receptive field associated with one sensory neuron -secondary sensory neuron: turn synapses on one CNS neuron -also called "first order and second order neurons" -afferent neuron="first order" neuron

Phototransduction

-rhodopsin: opsin (protein embedded in rod disks) and retinal (vit A deriv) -no light: retinal binds to site on opsin, when activated by light photon, no longer binds to opsin, released from pigment: bleaching -electrical signals in cells: result of ion movement b/t ECF and ICF -3 types of cation channels for rods (cyclic nuecleotide gated channels)

photoreceptors transduce light into electrical signals

-rods: fxn in low light, night vision, seen in black and when, outnumber cones 20:1, except in fovea (only cones) most abundant in retina, more sensitive to light -cones: high acuity vision, color vision daytime, to sharpen/keenness, fovea: sharpest visual acuity also 1) outset segment, tip touches pigment epithelia of retina 2)inner segment with cell nucleus and organelles for ATP synthesis and protein syn 3)basal segment with synaptic terminal that releases glutamate on bipolar cells -visual pigments: bound to disk membrane in outer segment of photoreceptors, convert light energy into change in mem potential -Disks of a photoreceptor are located in the outer segment and contain photopigment -rhodopsin: type of visual pigment in rods, excited by wavelengths of light, allow us to see color, red, green, blue: colors of visible light -color blindness: defect in one or more cones, difficulty distinguishing certain colors (red-green)

olfaction

-sense of smell -olfactory bulb: extension of forebrain that recieves input from primary olfactory neurons -second order neurons synapse with this -basal cells are precursor for olfactory cells

coding and processing distinguish stimulus properties

-tell difference b/t pin prick to toe and hand -CNS distinguishes b/t 1) its nature/ modality -depends on which sensory neurons are activated and where their signals terminate 2) location -phantom limb pain: secondary sensory neurons become hyperactive -lateral inhibition: inc contrast b/t activated receptor fields and inactivated neighbors (isolate location of stimulus)produces contrast within the nervous system, Lateral inhibition enhances acuity.decreases the two-point discrimination threshold, occurs when communication is inhibited to second-order neurons receiving information from afferents associated with neighboring receptive fields. -lateral displacement;of bipolar and ganglion cells within the macula lutea allow for an unhindered pathway for light to reach the cones of the fovea -population coding: the way multiple receptors function together to send CNS more info than would b possible from a single receptor 3)its intensity -not determined by single "all or none" action potential -number of receptors activated (population coding) and frequency of action potentials from those receptors (frequency coding) -Frequency of sound is coded for by the location of the hair cell stimulated in the cochlea 4) its duration -coded by duration of action potentials by sensory neuron -generally, longer stimulus: longer action potentials -stimulus persist, some receptors adapt or cease to respond 2 classes of receptors 1) tonic receptors: slowly adapting receptors that fire rapidly when first acitivated 2)phasic receptors: rapidly adapting receptors tha fire when they first receive stimulus but cease if strength of stimulus remains constant

3 classes of skin receptors

-thermoreceptors -nocionreceptors -chemoreceptors -cutaneous mechanoreceptors: Ruffini's end organ (stretch), Meissner's (change in texture, slow vibrations), Pacinian (deep pressure, fast vibrations) * all go to somatosensory cortex for processing

signal processing begins in retina

-third step -multiple neurons synapse on postsynaptic cell -horizontal cells: synpase with photoreceptors and bipolar cells to mediate lateral inhibition in retina -lateral inhibition enhances stimulus location and cotnrast -amacrine cells: modulate info bt bipolar and ganglion cells

nontraditional taste sensations

-tongue: taste receptor for fats -CD 36 receptor -taste sensations related to somatosensory rather than taste receptor cells -specific hunger: lacking a particular nutrient: develop craving for that substance -salt appetite: lack of Na+ in the body

primary sensory neuron

-triggered by action potential of receptor activation -in PNS they are pseudounipolar neurons whose nerve cell bodies lie in the dorsal root ganglia alongside spinal cord -their axon terminals synapse in the CNS onto interneurons that serve as secondary sensory neurons -secondary cross midline of body: sensations from left produced in right side (vice versa) -secondary synapse onto tertiary sensory neruons in thalamus, project to somatosensory region of cerebral cortex

salt taste

-type 1? -na+ entry, depolarization

sour taste

-type III presynaptic cells -increasing H+ -H+ mediated depolarization, release in serotonin by exocytosis, excites primary sensory neurons

Oolith organs

-utricle and sacule arranged to sense linear forces -hair cells in utricle: used to detect linear acceleration forward or backward -maculae (sensory structures): hair cells and gelatinous mass (oolith membrane), calcium carbonate particles (ooliths) -hair cell cilia embedded in oolith membrane and bind to matrix proteins on membrane surface -gravity or acceleration causes ooliths to slide, membrane slides with them, bending hair cilia and sending off a signal

vestibular nerve

-vestibular cells release neurotransmitter onto primary sensory neurons of vestibular nerve -synapse with vestibular nuclei(located in brainstem) or to the cerebellum (equilibrium processing)

parallel processing

-visual system, visual details are transmitted along separate pathways to the primary visual cortex where they are then integrated.

Phototransduction occurs at retina

-when light hits retina, photoreceptors convert light energy into electrical signals --large spectrum of light, brains can only percieve a small range of this light -visible light: limited to electromagnetic energy with waves of 4.0-7.5x10^14 Hz, wv of 400-750nm -electromagnetic energy is measured in photons -our eyes don't respond to ultraviolent and infared -photransduction: animals convert light energy into electrical signals -5 types of neurons in retinal layers: photoreceptors, bipolar cells, ganglion cells, amacrine cells, horizontal cells -retina has glial cells(astrocytes) and müller cells, support cell -pigment epithelium layer: back photosensitive portion of human retina, absorbs light rays that escape photreceptors -photoreceptors: neurons that convert light energy into electrical signals (rods and cones) -fovea: free of neurons and blood vessels, blocks light reception, photoreceptors receive light directly -fovea and macula: immediately surround area of acute vision and form center of visual field -sensory info about light passes from photoreceptor to bipolar neurons to ganglion cells. axons of ganglion cells form optic nerve, leaves eye at optic disk. no pr in optic disk, images on this spot can't be seen: blind spot -trasmit info directly to bipolar cells, graded potential proportional

olfactory signal transduction

1) Odorant binding to olfactory receptor -(G-protein linked receptor) 2) G-protein cascade activation - odorant molecules with olfactory creates G(olf), inc cAMP, inc cAMP gated channels, depolarizes cell, can create action potential 3) Opening of the ion channel

summary of speicificty of sensory pathway

1) receptor is sensitive to particular type of stimulus 2)stimulus above threshold initiates action potenail in sensory neuron that projects to CNS 3) stimulus intensity and duration are coded in patterns of action potential reaching CNS 4)stimulus location andmodality are coded according to which receptors ar activated by timing of receptor acivation 5)each sensory pathway projects to spcific region of cerebral cortex dedicated to particular receptive field. brain can tell oringin of each incoming cell

sensory tradsduction converts stimuli into graded potentials

1) transduction: conversion of stimulus energy into info that can be processed by nervous system - convert stimulus energies into changes in membrane potential? 2) each sensory receptor has adequate stimulus: particular form of energy to which it is most responsive 3)threshold: minimum stimulis to activate receptor 4) conerted into membrane potential by opening/closing ion channels in receptor membrane 4) change in sensory membrane potential: receptor potential (graded potential)

cochlea filled with fluid

3 parts of cochlea 1) vestibular duct 2) cochlear duct 3) tympanic duct -vestibular and tympanic connect at helicotrema -vestibular and tym simiilar in ion comp to perilymph -cochlear duct filled with endolymph (high K+, low na+ conc)...endolymph found in scala media -duct contains organ of corti:, which sits on basilar membrane and it partially covered by tectorial membrane (tips of stereocilia embedded here) -hair cells: nonneural receptor cells, apical surface is modified into stiffened cilia (stereocilia) -hair cells move in response to sound waves, stereotcilia flex one way and the =other -stereocilia attatched by tip links -Bending of the stereocilia on the hair cell can induce either a closure or an opening of a potassium channel based upon the direction the stereocilia move

adaptation

A decrease in the amplitude of a receptor potential over time in the presence of a continued stimulus is called habituation.

general properties of sensory systems

It begins with a stimulus in the form of physical energy acting on a sensory receptor. Transducer concerts stimulus into intracellular signals to change membrane potential. If above threshold, action potentials travel to CNS to be integrated -simplest systems: single sensory neurons -complex systems: multicell sense organs (ear, eye)

cribiform plate

The bone overlying the olfactory epithelium is called the

How is the intensity of a stimulus encoded during information transmittal to the central nervous system?

The frequency of action potentials transmitted to the central nervous system is greater for a stronger stimulus.

olfactory pathways

The olfactory epithelium lies high within the nasal cavity, -olfactory sensory neurons project to the cavity -axons of olfactory neurons form olfactory nerve -olfactory nerve synapses with secondary neurons in olfactory bulb -secondary and higher order neurons project from olfactory bulb through olfactory tract to olfactory cortex\ -complex processing and pathways

baroreceptor

type of receptor detects blood pressure

signal transduction

The process whereby a sensory receptor converts a stimulus modality into a change in membrane potential is called

third order neuron

What type of neuron in the thalamus communicates sensory information to the cerebral cortex?

polymodal nociceptors

type of receptor responds to chemicals like histamine and bradykinin that are released from damaged tissue

olfactory epithelium

a thin layer of tissue, within the nasal cavity, that contains the olfactory sensory neurons -olfactory sensory neurons have very short lives -in rodents: vomeronasal organ: accessory olfactory structure, behavioral response to sex pheromones

Proprioception

awareness of body movement and position in space -mediated by sensory receptors (proprioreceptors), unconscious or conscious - The perception of the position of one's joints and limbs is called

ganglion cells

bipolar cells synapse with ganglion cells which group together to form the optic nerve -lie on surface of retina -ganglion receives info from visual receptive fields -receptive fields are circular, round center and doughnut shaped surround -on center and off center ganglion cell receptive fields ex) if light is brightest in off, on is inhibited -M cells( more sensitive to info) and P(sensitive to signal) cells make up ganglion cells in retina and melanopsin retinal ganglion cell: relay info about light cycles to suprachinistic nucleus - The first neurons capable of generating action potentials in the transmission pathway for visual information detected by rods and cones are the ganglion cells.

gustatory nucleus located in the

brainstem

The closure of sodium channels is mediated by a decrease in the cytosolic concentration of ________, which is degraded by ________.

cGMP, phosphodieterase

sustenacular cells

cells in the olfactory mucosa maintain the extracellular environment surrounding the receptor cells

hearing loss: mechanical or neural damage

conductive hearing loss: sound can't be transmitted through external or middle ea, conductive hearing loss -central hearing loss: damage to neural pathways b/t ear and cerebral cortex, damage to cortex itself -sensorineural hearing loss: damage to structures of inner ear, death of hair cells -presibycusis: hearing loss in elderly (90%), sensoneurial: hearing aids and cochlear implants(microphone, speech processor, transmitter)

Osmoreceptors

detect t swelling of receptor cells

The cornea and lens are ________ surfaces that cause light to converge on a ________.

convex, focal point

Glossopharyngeal nerve (IX)

cranial nerve that transmits taste information to the central nervous system?

adaptation

decrease in the amplitude of a receptor potential in the presence of a continuing stimulus called

In the absence of light, the membrane potential of a photoreceptor is relatively ________ by the presence of open ________ channels.

depolarized, sodium

How are we able to perceive the three-dimensional character of the world around us?

depth perception: our ability to see objects in three dimensions, even though our retinas receive two-dimensional images. Without depth perception, we would be unable to judge distance , height, or depth

Whether the hair cell in the semicircular canal is depolarized or hyperpolarized is dependent upon which of the following?

direction toward which the stereocilia are bent relative to the kinocilium

CNS integrates sensory info

enters through spinal cord, down ascending pathways to brain -each division of brain processes one or more types of sensory info -all these pathways then are relayed to the thalamus which relays and proceses info to the cerebrum -only olfactory info is not routed through the thalamus (goes straight to olfactory cortex in cerebrum) -perceptual threshold: level of stimulus intensity for you to be aware of a particular sensation -decreased perception of stimulus (habituation) accomplished by inhibitory modulation: diminishes suprathreshold stimulus until its below perceptual threshold

the ear: equilibrium

equilibrium: state of balance, dymanic component (tells about movement) and static component (tells us if we are upright) -sense of equilibrium mediated by hair cells linin vestibular apparatus in inner ear -vestib hair cells have single long ciliium (kinocilium) ref point for direction of bending

In a neural pathway, when an excitatory synapse follows an inhibitory synapse, this is called disinhibition.

false

Receptive field sizes are approximately the same over all parts of the body for a specific modality.

false

Taste receptor cells are located only on the tongue

false

The second-order neurons in the olfactory pathway are called ________ cells.

glomeruli

taste

gustation -sweet, sour (acid), salty, bittter, umami -sweet, bitter, umami activated by g-protein coupled receptors (gustducin: activates signal transduction pathways,causes K+ channels to close), taste II receptors cells, ATP released through calcium homeostatis modulator (wide pore channel protein) -salty, sour: ion channels

Depolarization of hair cells in the utricle occurs when the

hair bends towards kinocilium

he ganglion cells of the retina synapse with neurons in the ________ that ascend to the ________.

lateral gentriculate body, primary visual cortex

greatest tactile acuity

lips

The primary afferent neurons from taste receptor cells terminate within what structure of the central nervous system?

medulla oblongata

First-order olfactory neurons synapse with ________. These synapses occur in clusters called ________.

mitral cells, glomeruli

In the optic chiasm, ganglion cells from the ________ portion of the retina cross over, whereas the ganglion cells from the ________ portion of the retina remain on the same side.

nasal, temporal

near vision/ distant vision

near: Ciliary muscles contract, causing zonular fibers to become slack, and the lens becomes rounder distant:ciliary muscles relax, lens becomes flat, long distance

Molecules must be dissolved in fluid to interact with the receptor for which of the following

olfaction

sensory system does NOT need to transmit information through the thalamus to reach the cortex

olfaction

In terms of a bad smell, why is it better to stay in its presence than to leave and return several times?

olfactory receptors are rapidly adapting

Ciliary muscle is innervated by what branch of the nervous system?

parasympathetic -nder parasympathetic control to regulate the refractive power of the lens

somatosensory cortex

part of the brain that recognizes where ascending sensory tracts originate -each sensory tract has corresponding region of cortex: sensory field -fMRI and PET scans watch brains at work -found in parietal lobe

phasic receptors vs tonic receptors

phasic:are better able to provide information on whether a stimulus has changed, tonic:better adapted to provide information on the extent of that change.

order of communication of visual information in the retina

photoreceptor, bipolar cell, ganglion cell

components of the neural pathway for vision in the correct order, starting with the photoreceptor and ending with the visual cortex

photoreceptor, bipolar cell, ganglion cell, optic nerve, optic chiasm, optic tract(neural pathway from the lateral geniculate body to the visual cortex), lateral geniculate body, optic radiations, visual cortex

vision

process through which light reflected from objects in our environment is translated into a mental image 3 steps 1) light enters eye, focuses light on retina (neural tissue that includes bipolar cells) 2)photreeceptors of retina transduce light energy into an electrial signal 3) neural pathways from retina to brain process electrical signals into visual images

afferent division of nervous system

provide us with info about environment and inside our bodies

mechanical nocioceptors

receptor type is used to detect intense mechanical stimuli

modality

refers to the form of energy that defines a specific stimulus.

law of specific nerve energies, single sensory receptor responds to

responds best to a specific energy modality. -defined by the pathway over which the sensory information is carried. Hence, the origin of the sensation is not important. Therefore, the difference in perception of seeing, hearing, and touch are not caused by differences in the stimuli themselves but by the different nervous structures that these stimuli excite

The light-absorbing portion of the photopigment is ________; its sensitivity to a particular wavelength of light is altered by ________.

retinal, opsin

When we enter a dark room, the retinal and opsin molecules within the ________ must first ________ before low light levels can be detected.

rods, associate

sensory-discriminative dimension of pain and affective- motivational dimension of pain

sensory: associated with processing in the primary and secondary somatosensory cortex, encompasses the perceived intensity, location, and quality of painful affective: perceived unpleasantness of an event

sensory unit

single afferent neuron and all of the sensory receptors associated with that neuron.

Two point discrimination test

size of secondary receptive fields determines how sensitive a given area is to a stimulus found in more sensitive areas of skin and have smaller receptive fields the 2 stimuli activate separate pathways to the brain

Chemoreception

smell and taste

What two taste qualities use a G protein during the transduction process

sweet, bitter

The radial muscles of the iris are innervated by the ________ nervous system and their contraction causes pupillary ________.

sympathetic, dilation

taste pathways

taste buds: receptors for taste..one taste bud=50-150 taste receptor cells -taste receptor cells : has receptor cells that are modified epithelial cells -taste buds: four cell types: I,II,III, basal (IV) brain stem, taste center in the thalamus (gustatory cortex in frontal lobe)

location of the medial geniculate body

thalamus

second order neurons terminate in the

thalamus

The ability to detect the direction from which a sound originates is determined by

the time delay between that sound reaching the right and left cochlea.

Proprioceptors provide the body with continuous information that changes little as a particular joint angle is maintained, and are therefore an example of ________ receptors.

tonic, slowly adapting

somatic senses

touch, temperature, pain, itch, proprioception

Along a large portion of the retina, light must pass through two layers of cells before reaching a photoreceptor.

true

Capsaicin causes a burning sensation in the mouth because it binds to TRPV1 receptors.

true

Extensive convergence exists from the cones to the bipolar cells within the fovea.

true

Modulation of sensory information as it is transmitted from receptors to the cerebral cortex can only occur at synapses.

true

The concentration of cGMP in a photoreceptor is relatively high in the dark, thereby maintaining rods and cones in the depolarized state.

true

We generally do not perceive information transmitted by visceral afferents

true

the dorsal column-medial lemniscal pathway carries mechanoreceptive and proprioceptive information to the thalamus, whereas the spinothalamic tract carries thermoreceptive and nociceptive information.

true

sound transduction

turns air waves into mechanical vibrations then fluid waves which open ion channels in hair receptors, ion flow creates electrical signals which release neurotransmitter (chemical signal), and finally action potentials

Sound waves traveling through the air initiate a vibration of the ________. The sound waves are then transmitted along the ________ to the cochlea.

tympanic membrane, ossicles

spinothalamic tract cross over to the opposite side

ventral white commissure in anterior spinal cord

Afferent neurons (first-order neurons) from the semicircular canal, the utricle, and the saccule enter the brainstem where most terminate within the

vestibular nuclei -brainsteam holds dorsal columns

special senses

vision, hearing, taste, smell, equilibrium

anterior segment

within the eye, between the iris and lens