Physio Ch. 10, Sensation

hrdcorhrvivor's version from 2017-03-07 11:27

Section 1

Question Answer
sensationconscious or unconscious awareness of changes in external or internal environment
4 general properties of sensory systems1. stimulus, physical energy that acts on receptor. 2. receptor, acts as a transducer. 3. sensory neruon, sends AP if the stimulus reaches threshold. 4. CNS, site of integration of signals
general sensessomatic -> touch, pain, proprioception. visceral -> provide info about condition in the internal organs, stretch, pressure, hunger
special sensessmell, taste, vision, hearing, equilibrium
mechanoreceptormechanical stimulus
3 ways we classify receptors based on locationexteroreceptor, located at/near body surface. interoreceptor: bv, internal organs, NS. proprioceptor: muscles, tendons, joints, inner ear equilibrium
sensory transductionconverting physical stimulus into electrical impulse
law of specific nerve energythe nature of perception is defined by the pathway that the sensory info is carried
receptor potentialstimulus activates a receptor that causes change in membrane potential creating a graded potential, can cause AP or influence NT release
small v large receptor fieldsone field with one secondary sensory neuron. multiple fields associated with one secondary sensory neuron, overlap
punctuate distributionsensory receptor fields are not evenly distributed among body
tactile localizationthe ability to identify without looking the exact point on the body where a stimulus is applied
what is habituation and how can it be achieved?decreased perception of a stimulus, must reach perception threschold, accomplished by diminishing stimulus that is above threshold

Section 2

Question Answer
distinguishing stimuli 4 properties1. modality 2. intensity 3. location 4. duration
modality in stimulibrain will perceive a signal coming from a certain receptor, cold receptor always senses cold
location of stimuliwhich receptive fields are activated, lateral inhibition: enhances contrast between receptive fields, primary neuron same as stimulus strength, secondary inhibits nearby neurons
intensity of stimuliCNS cannot code for intensity just using AP because its not the size of AP but how many are activated and the frequency
duration of stimuliusually long stimulus means long AP, some adapt. tonic receptors: slow adapting, pain. phasic receptors: fast adapting, wearing glasses on head.
encapsulated touch receptorsmeissner's corpuscle, pacinian corpuscle, ruffini corpuscle
unencapsulated touch receptorsfree nerve endings, merkel receptors (discs)
meissner's corpusclelight touch
pacinian corpusclepressure
ruffini corpusclelight touch
free nerve endingsitch
merkel receptors light touch
range of warm thermoreceptorsbetween 37 C and 45 C, anything higher than 45 C nociceptors activated
nociceptors fast painsharp localized, delta fibers, myelinated
nociceptors slow paindull diffuse, c fibers, slow fibers
referred painpain is perceived as arising in one area when another area is receiving the pain, brain freeze

Section 3

Question Answer
proprioreceptors allow us to recognize parts of our body belong to us, where head/ limbs are
muscle spindlesencapsulated sensory nerve fibers and intrafusal fibers (sensory and motor receptors) monitor changes in length of muscle, stretch relfex
golgi tendon organjunction of a tendon and a muscle, protect tendons from excessive tension, encapsulated
olfaction | type of receptor, specific receptor, region of brain integration occurschemoreceptor, N/A, olfactory apparatus in temporal lobe. ligand binding activates GPCR Golf, creates cAMP -> AP to olfactory bulb
glomerulieach cell responds to 1 smell
gustation | type of receptor, specific receptor, region of brain integration occurschemoreceptor, taste buds, primary gustatory area in parietal lobe.
sour and saltymediated by ions, sour H+ passes through channels, Ca2+ channels activated. salty Na+ passes through channels, Ca+ channels activated
sweet, bitter, umamimediated by macromolecules. sweet: sugar binds to receptor w special g protein gustducin, AC activated, cAMP produced, K+ channels close. bitter: quinine binds to receptors w gustducin, activated IP3 released Ca2+. umami, glutamate is the ligand
hearing | type of receptor, specific receptor, region of brain integration occursmechanoreceptors, hair cells (stereocilia), primary auditory area in temporal lobe
vision | type of receptor, specific receptor, region of brain integration occursphotoreceptors, rods and cones, primary visual area in occipital lobe
equilibrium | type of receptor, specific receptor, region of brain integration occursmechanoreceptors, maculae and ampulla, cerebrum

Section 4

Question Answer
depolarization of earstereocilia bent TOWARD the kinocilium, NT release, increase AP in cranial nerve 8
hyperpolarization of earstereocilia bent AWAY from kinocilium, less NT, decrease AP to cranial nerve 8
membranous labryrinthendolymph
bony labrynthperilymph
otolith organsdetect linear acceleration and head position
semicircular canalsdetect rotational acceleration
ampullaat the base of each semicircular canal, contains the cristae, inside gelatinous cupula
how is rotation sensed?head turns, endolymph moves slower than head, bends capula and stereocilia in opposite direction of movement, AP stimulated
maculareceptor found in each otolith organ, hair cells embedded in gelatinous otolithic membrane, calcium carbonate crystals called otoliths
reception of stimulusgravity or acceleration moves otoliths, membrane slides with otoliths, hair cells are bent AP
outer ear containspinna (auricle), external auditory meatus, tympanic membrane PET
middle ear containsossicles, eustachian tube
inner ear contains oval window, cochlea
cochlea chamber: scala vestibulisuperior, perilymph
cochlea chamber: scala tympaniinferior perilymph
cochlea chamber: cochlear ductmiddle, endolymph, organ of corti
cochlea membrane: vestibular membraneseparates cochlear duct from scala vestibuli
cochlea membrane: basilar membraneseparates cochlear duct from scala tympani
cochlea membrane: tectorial membranerigid membrane
organ of corticontains stereocilia and supporting cells, attatched to basilar and partially covered by tectorial membrane
hearing processsoundwaves hit tympanic membrane and become vibrations, vibrations go to ossicles, ossicles vibrate the oval window which moves fluid within cochlea, fluid pushes against membranes of cochlear duct, hair cells bend ion channels open, NT release onto sensory neurons creates AP, travels through cochlear nerve to brain, energy from waves transforms across cochlear duct to tympanic duct and is back out the middle ear

Section 5

Question Answer
scleraouter white coating, apaque, clear anterior region is cornea
choroidmiddle vascular layer, ciliary body: SM connected to lens, aqueous humor.
irisSM changes size of pupil, controls amount of light entering eye, SNS: dilation, PSNS: contraction
aqueous humorliquid, nutrition for the ye, anterior cavity
vitreous humorgelatinous, maintains shape of eye, posterior cavity
refractionlight passing from one media to the next will be bent
site of refraction: 1st cornea, 2nd lens, 3rd, aqueous humor, 4th vitreous humor
accommodationability to keep image focused as distance varies
emmetropianormal vision
astigmatismirregular cornea or lens
retnaneutral layer, contains photoreceptors rods and cones, macula lutea (focal point) and fovea centralis (highest concentration of cones)
axons of the retina exit via the optic disc
rodsdim light, black/white vision, rhodopsin (adjusting)
coneshigh light, color vision, 3 pigments: red, blue, green
bleaching reactionlight causes rhodopsin to dissociation into opsin and retinal, opsin activates transducin cascade. leads to drop in cGMP, CNG channels close, NT release decreases
dark adaptionwhen there is no light: rhodopsin intact, rods increase sensitivity, high amount of cGMP, NT released
pathway to the brain1. photoreceptors activated 2. synapse with bipolar cells 3. bipolar cells synapse with ganglion cells (m cells:movement p cells: fine detail) 4. ganglion cell axons exit via optic nerve
optic nerves cross atoptic chiasma