LAB 3 Flashcards
what are sensory receptors?
specialized cells or dendrites of sensory neurons that provide CNS w/ info abt body’s internal/external conditions
why are photoreceptors in retina stimulated by light rays but not smells or sounds?
most receptors are sensitive to one particular stimulus but relatively insensitive to others
what are the general senses?
- pain, warmth, cold, tactile, proprioception
- stretch, chemical, pressure
what are the special senses?
- vision
- olfaction
- gustation
- hearing
- equilibrium
what must happen for a sensation to be consciously perceived?
nerve impulse initiated by sensory receptor must be conducted to CNS and must reach region of brain where stimulus perceived and interpreted
what happens to nerve impulses that reach cerebral cortex?
they are consciously perceived as sensations
what happens to nerve impulses that are interpreted at the level of the spinal cord or brainstem
they do not reach cerebral cortex, so they cause a reflex response but conscious perception does not occur
what are the somatic senses?
- tactile
- warmth
- cold
- pain
- proprioception
where are somatic sense receptors located?
in the skin, or embedded in muscles, tendons, and joints
what are cutaneous sensations?
sensations perceived by somatic sense receptors located in the skin
where are receptors for visceral senses located?
in the internal organs
what are the visceral senses?
- stretch
- chemical
- pressure
where are stretch receptors found?
walls of hollow organs
where are chemical receptors found?
in epithelium of hollow organs
what are the two structural types of somatic sensory receptors?
- free nerve endings
- encapsulated nerve endings
what is special about encapsulated dendrites’ capsule?
type of connective tissue capsule around encapsulated nerve endings enhances its sensitivity or specificity to a stimulus
what structural type of neurons are the free and encapsulated nerve endings?
pseudounipolar neurons
what are tactile corpuscles?
- encapsulated nerve endings
- **detect onset of touch
- detect low frequency vibration**
- found in dermal papillae of highly sensitive areas of hairless skin
what are hair root plexuses?
free nerve endings wrapped around hair follicles
- detect movement that disturb hairs
what are nonencapsulated sensory corpuscles?
- Merkel discs/tactile discs
- free nerve endings
- associate w/ tactile epithelial cells in stratum basale of highly sensitive areas of hairless skin
- detect pressure and continuous touch
- numerous in fingertips, hands, lips
what are bulbous corpuscles?
- ruffini corpuscles
- encapsulated receptors deep in dermis, in ligaments and in tendons
- detect stretching and steady pressure
what are lamellar corpuscles?
- encapsulated dendrites
- in dermis and subcutaneous regions
- detect high frequency vibrations
- detect steady pressure
what are free nerve endings?
- stimulated by certain chemicals
- tickling is result of stimulation of a free nerve ending
- found in skin
- senses pain, itch, cold, warmth
Describe how to detect touch/test the hair root plexus
- observe fine hairs on arm or back of hand
- gently move one hair in multiple directions w/ pencil tip
- flick hair rapidly several times
should there be difference in sensation felt between slow and fast stimuli when testing hair root plexus?
flicking hair rapidly will cause more frequent nerve impulses while gently moving the hair will send less frequent nerve impulses
should there be difference in sensation felt when two or three hairs are touched simultaneously when testing hair root plexuses?
Yes, stronger stimulus because more receptors are stimulated
what is tactile localization?
the ability to determine which portion of skin has been touched
why do some areas of the body have greater tactile sensitivity than others?
there are greater numbers of sensory receptors that detect tactile sensations in those body areas than other body areas
describe the relationship between receptor density and sensitivity
the greater the receptor density, the greater the sensitivity
describe the procedure for testing tactile localization
- subject closes eyes, arms held loosely away from body, elbows vent, one palm facing up with fingers spread while other hand hold green marker, tester touches subject’s fingertip w/ red marker
- subject tries to touch exact point w/ green marker, measure distance error
- repeat two times, aiming for same red spot and recording distance error
- repeat procedure on upper anterior forearm w/ no hair
which body areas have smallest area of localization?
fingertips
Can the ability to localize stimulus improve w/ subsequent attempts?
No, receptor density does not change
Describe the procedure for the two-point discrimination test
- subject’s eyes closed, start w/ closed caliper arms, tester should touch subjects palm w/ both points simultaneously w/ equal light pressure and ask if subject feels 1 or 2 pts.
- increase distance btwn caliper pts, continue until subject reports 2 pts contact is felt, measure distance
- repeat procedure w/ fingertip, back of hand, upper anterior forearm, back of neck, and forehead/cheek
what is the two-point threshold?
distance that two distinct and separate points of contact are felt
which body areas have the lowest two-point threshold?
fingertips
which body areas have highest two-point threshold?
back of head
describe the distribution of touch receptors in areas of body w/ lowest and highest two-point touch thresholds
areas w/ lowest two-point touch threshold have high density of cutaneous mechanoreceptors
areas w/ highest two-point touch threshold have low density of cutaneous mechanoreceptors
what type of touch receptors respond to two-point touch threshold test?
- cutaneous mechanoreceptors
- tactile corpuscles
- tactile discs
what detects thermal sensations?
free nerve endings
what are cold receptors?
free nerve endings in stratum basale that detect 10-35°C
what are warm receptors?
free nerve endings in dermis that detect 30-45°C
describe thermal receptor distribution test
- draw rectangle 4x10mm on anterior surface of subject forearm w/ marker, diving rectangle into 10 squares, avoid hairy areas
- subject’s eyes closed, tester dried cold probe and touches small square w/ dry cold probe
- if cold, mark “c” on square, if no cold, “x”, if no touch felt, “o”
- repeat procedure on other 9 squares
- repeat procedure w/ dry warm probe, if hot, “h”
explain results of thermal receptor distribution test in terms of specificity and distribution of hot and cold receptors
warm and cold receptors distributed independently, there are more cold receptors on skin, hot receptors do not perceive warm stimuli as accurately as cold receptors
what are nociceptors?
free nerve endings that detect pain
- found in all body tissues except brain
- stimulated by chemical/physical damage to tissue
what is proprioception?
sense of body position in a three dimensional space
- enables you to walk w/o looking at feet, or touch ear w/o looking at mirror
where are proprioceptors found?
- synovial joints
- tendons
- skeletal muscles
what are proprioceptors?
nerve endings that convey info abt position of a joint, degree of muscle contraction, and amount of tension in tendons
which major parts of brain receive input from proprioceptors?
- cerebellum
- brainstem
describe procedure for testing proprioception?
- using pencil, draw small circle (1cm diameter) in middle of sheet of paper
- using red pen, place tip in middle of circle, remain in position w/ eyes closed for 15s, only elbow and pen touches table
- w/ eyes closed, lift pen 5-8cm off paper and make mark in circle, repeat until 10 marks made on paper
- repeat procedure w/ non-dominant hand and blue pen
why is there a difference in accuracy between dominant hand and non-dominant hand when testing for proprioception?
- dominant hand more accurate, higher density of proprioceptors
- more sensitive to pressure and tension changes
- brain hemisphere that controls dominant hand more developed for motor skills
where are sensory receptors for olfaction?
in olfactory epithelium lining roof of nasal cavity
what classification are sensory receptors for olfaction?
chemoreceptors - responds to chemicals in solution
what do olfactory glands in lamina propria secrete?
mucus
how are odorant molecules smelled by olfactory cilia?
odorant molecules diffuse through air to nose and dissolve in mucus to stimulate olfactory cilia
describe pathway of olfactory stimuli to olfactory nerve
air → nose → dissolve in mucus → olfactory cilia
olfactory sensory neurons’ axons → cribriform plate of ethmoid bone → olfactory bulbs
what are olfactory cilia?
hairs that project from dendrites of olfactory sensory neurons
why do colds or allergies affect sense of smell
- olfactory sensory neurons are affected/destroyed by pathogens
- too much mucus blocks odorant molecules from coming into contact w/ olfactory cilia
- inflammation obstructs olfactory epithelium
what is the olfactory tract?
bundle of axons extending posteriorly from olfactory bulb to olfactory regions of cerebral cortex
what is the olfactory bulb?
swollen ends of olfactory nerve, synapses w/ axons of olfactory sensory neurons coming from olfactory epithelium, conveys olfactory info to brain
what is the ethmoid bone?
bone where olfactory nerves pass through, contains cribriform plate and cribriform foramina
what is the cribriform plate?
process on ethmoid bone where cribriform foramina are located, where olfactory nerves pass through
- olfactory epithelium covers inferior surface of cribriform plate
what is the nasal cavity?
cavity containing olfactory epithelium that occupies its superior portion
what are the olfactory glands?
glands that produce mucus carried to surface of epithelium by ducts
- within connective tissue that supports olfactory epithelium
- innervated by parasympathetic fibres of facial (VII) nerve
what is the mucus made by olfactory glands?
mucus moistens olfactory epithelium surface, dissolves odorant molecules so transduction of olfactory stimuli can occur
what are olfactory sensory neurons?
bipolar sensory neurons found in olfactory epithelium that transduces odors into neural signals, responds to chemical stimulation of odorant molecules by producing receptor potentials
what are odorant molecules?
chemicals that bind to and stimulate olfactory sensory neurons by coming into contact w/ olfactory cilia
Describe procedure for testing olfactory adaptation
- Vial A: peppermint, Vial B: pepprmint+cloves
- smell each vial and identify odours
- smell Vial A continuously for 4min and note time until no longer notice smell
- Quickly switch to Vial B and note what odor is smelled
what happened in terms of adaptation of the smell receptors in the olfactory adaptation test?
- olfactory sensory receptors send receptor potentials at lower amplitude than initially due to maintained, constant stimulus
- lower amplitude = less frequent nerve impulses
- perception of sensation fades/disappears
when does olfactory adaptation occur in real life?
olfactory sensory neurons adapt by 50% in 1st sec after stimulation but adapt very slowly thereafter
- complete insensitivity to certain strong odours occur ~1min after exposure
is olfactory adaption desirable?
Yes, can allow us to focus on other stimuli in a strong-smelling environment
where are sensory receptors for gustation located?
in taste buds of tongue, soft palate, pharynx, and epiglottis
what are taste buds?
onion-shaped groups of cells located in stratified squamous epithelium of tongue, on lingual papillae
what are lingual papillae?
elevated areas of tongue
what are gustatory epithelial cells?
epithelial cells w gustatory microvilli (hairs) that projects through taste pore at apical end of taste bud
what classification of receptors are taste buds?
chemoreceptors; food molecules must be dissolved in saliva to make contact w/ gustatory microvilli
what happens at basal end of taste buds?
gustatory epithelial cells synapse w/ dendrites of 1st order taste neuron that has contact w many gustatory epithelial cells in several taste buds
what are the cranial nerves that transmit from sensory information from taste buds to brain?
- Facial (VII) nerve
- Glossopharyngeal (IX) nerve
- Vagus (X) nerve
describe the procedure for testing the effect of smell on taste
- subject sniffs vials w/ peppermint and clove oil and try to identify them
- subject dries tongue, closes eyes, and plugs nose; tester dips new cotton swab in cloves, and touches anterior 1/3 of tongue w/ swab and note if subject can detect the flavour
- have subject unplug nose and note change in sensation, rinse mouth
- have subject sit w/ eyes closed and mouth open, tester dips new swab in peppermint and new swab in cloves, hold peppermint under nose while simultaneously touching clove on tongue and note flavour subject tastes
is smell or taste more important in proper identification of strong substance?
smell, smells trick us into thinking we are tasting that substance
describe the procedure for testing chemoreception in gustation
- dry tongue surface w/ paper towel and place freshly unwrapped candy on anterior 1/3 tongue, keeping mouth open
- time how long it takes to taste the candy
- remove candy, rinse mouth
- repeat experiment w/ well moistened mouth, use new candy if you wish
what conclusions can you draw about chemoreception and gustation in their respective test?
IDK
what are the two types of receptors found in the retina?
- rods
- cones
how is the eye protected?
- eyelids, eyelashes, eyebrows
- lubrication system of tear glands and ducts
what is the lacrimal gland?
secretory cells located at superior anterolateral portion of each orbit
- secretes tears into excretory ducts that open onto surface of conjunctiva
what is the lacrimal sac?
superior expanded portion of the nasolacrimal duct that receives the tears from a lacrimal canal
- in lacrimal fossa of lacrimal bone
describe the path tears take from lacrimal glands to excretion
lacrimal gland → lacrimal canaliculi → lacrimal sac → nasolacrimal duct
what is the eyelid?
palpebrae
- shades eyes during sleep
- protects eyes from excessive light and foreign objects
- spreads lubricating secretions over eyeballs
what is the pupil?
hole in center of iris
- autonomic reflexes regulate pupil diameter in response to light lvls
what is the iris?
colored muscle of eyeball that regulates amount of light entering eyeball through pupil
- suspended btwn cornea and lens
- attached at its outer margin by ciliary processes
what is the sclera?
“whites” of the eye
- layer of dense connective tissue, mainly collagen fibres and fibroblasts
- gives eyeball its shape, makes it more rigid, protects inner parts
- covers entire eyeball except cornea
- serves as attachment site for extrinsic eye muscles
what innervates superior rectus?
oculomotor (III) nerve
what innervates inferior rectus?
oculomotor (III) nerve
what innervates lateral rectus?
abducens (VI) nerve
what innervates medial rectus?
oculomotor (III) nerve
what innervates superior oblique?
trochlear (IV) nerve
what innervates inferior oblique?
oculomotor (III) nerve
superior rectus
elevates, adducts, and medially rotates eyeballs
inferior rectus
depresses, adducts, and laterally rotates eyeballs
lateral rectus
abducts eyeballs
medial rectus
adducts eyeballs
superior oblique
depresses, abducts, and laterally rotates eyeballs
inferior oblique
elevates, abducts, and laterally rotates eyeballs
what is ciliary body?
what the choroid becomes in anterior portion of vascular tunic of eyeball
- dark-brown, contains melanocytes
- contains ciliary muscles that alters shape of lens to adapt for near/far vision
what are the ciliary muscles?
circular band of smooth muscle
- contraction/relaxation changes tightness of zonular fibres, altering shape of lens to adapt for near/far vision
what are the ciliary processes?
folds on internal surface of ciliary body
- contains blood capillaries that secrete aqueous humour
what is the anterior segment of the eye?
space btwn cornea and lens that contains aqueous humour, maintaining shape of eyeball, suppliying oxygen to lens and cornea
what is aqueous humour?
transparent, watery liquid that nourishes lens and cornea
- replaced completely every ~90min
what is the anterior chamber of the eye?
- part of anterior segment, space btwn cornea and iris
what is the posterior chamber of the eye?
- part of anterior segment, space btwn zonular fibres&lens and iris
what is the cornea?
nonvascular, curved, and transparent fibrous coat covering the iris that helps focus light onto retina
- central part receives oxygen from air
- admits and refracts light
what is the lens?
cavity of eyeball, behind pupil and iris that helps focus images on retina to facilitate clear vision
- crystallins in cells of lens make up refractive media of the lens
what are the zonular fibres of the lens?
suspensory ligaments
- thin, hollow fibrils that extends from ciliary processes and attached to the lens
- ciliary muscle changes their tightness, adapting eyes for near/far vision by altering shape of lens
what is the bulbar conjunctiva?
thin, protective mucous membrane of nonkeratinized stratified squamous epithelium w/ goblet cells supported by areolar CT
- passes from eyelids onto eyeball surface, covering entirety of sclera but not cornea
what is the retina?
inner layer of eyeball consisting of nervous tissue that receives light and transduces it into receptor potentials and nerve impulses
- beginning of visual pathway
- consists of pigmented layer of epithelial cells that contact choroid
what is the choroid?
highly vascularized layer that lines most of internal surface of retina
- blood vessels provide nutrients to posterior surface of retina
- melanocytes in choroid absorbs stray light rays, so image cast on retina is sharp & clear
what is the macula?
“yellow spot” in exact center of posterior portion of retina, at visual axis of eye
- contains receptors for linear acceleration/deceleration and head tilt
what is the fovea centralis?
small depression in center of macula only containing cones
- area of highest visual acuity (sharpness of vision)
what is the optic disc?
site where optic (II) nerve exits eyeball, no photoreceptors found so light rays focused here won’t be interpreted as an image
what is the optic (II) nerve?
- exits eyeball through optic disc
- receives visual input from eyeball and transducts to brain for conscious processing
what is the posterior segment of the eyeball?
posterior portion of eyeball lying btwn retina and lens
- contains vitreous humour
what is the vitreous humour?
transparent, jellylike substance that holds retina flush against the choroid, giving retina even surface for reception of clear images
- mainly water, collagen fibres, and hyaluronic acid
- contains phagocytic cells, removing debris and keeping eyes unobstructed
which photoreceptors are involved in visual acuity?
cones
which photoreceptors are used to see in low light conditions?
rods
what is the Snellen eye chart?
chart that tests a person’s visual acuity/ their ability to see objects clearly at various distances
what is 20/20 vision?
normal vision
at a 20ft distance, a person w/ normal vision can read small 20/20 line on Snellen eye chart
what is emmetropia?
normal vision (20/20)
what is 20/100 vision?
difficulty seeing distant objects, you can see at 20ft what a person w/ normal vision can see at 100ft
what is myopia?
nearsightedness, lens of a person is unable to focus distant objects on retina, distant object is focused in front of retina and appears blurry
what is 20/15 vision?
objects you can clearly see at 20 ft are seen clearly by person w/ normal vision at 15ft
what is hyperopia?
farsightedness, lens of a person may focus nearby objects behind the retina, nearby objects appear blurry
describe the procedure for testing visual acuity
- subject stands 20ft from chart, covering left eye and reading each row of letters from left to right beginning at top of chart while tester tests for accuracy
- check line that was last read accurately
- have subject cover right eye and read chart w/ left eye
- repeat test w/ both eyes open
describe the test for colour blindness?
the book for congenital colour vision tests for colour blindness
what is colour blindness?
absence/deficiency of one of three photopigments located in the cones
- can be inherited/acquired
what is the cause of red-green colour blindness?
missing red/green photopigment in cones, preventing affected person from distinguishing red from green
- sex-linked recessive trait, passed on from mother to son via X-chromosome
what is astigmatism?
condition caused by irregular curvature of cornea/lens, images appear blurry/distorted due to improper focusing
describe procedure for testing astigmatism
- start 10ft from astigmatism chart and cover one eye, noting any disparity of thickness of the line groups
- switch eyes and repeat procedure
describe the procedure for testing the blind spot
- hold page of star and circle ~50cm from face
- close right eye and focus left eye on black dot, not letting it wander from dot
- slowly bring page closer to face until star disappears
- note distance page is from space
- slowly bring page even closer and note if star reappears
- move book away, star should disappear and reappear
- switch eyes in same manner, staring at star instead
what are intrinsic muscles of the eye?
muscles found inside eye
ex. ciliary muscles, circular and radial muscles of iris
what are extrinsic muscles of the eye?
muscles attached to outer surface (sclera) of eye
ex. rectus and oblique muscles
what do the extrinsic muscles accomplish?
attached to exterior of eye, makes it possible to keep moving object focused on fovea centralis
what happens when the eye is focusing on a close object?
ciliary muscles contracted, lens is more curved
what happens when the eye is focusing on a distant object?
ciliary muscles relaxed, lens is flat
describe the procedure for testing the accommodation pupillary reflex
- have subject stare at far wall for 1min
- tester observes diameter of subject’s pupils from front w/o blocking subject’s view
- while observing pupil size, tester holds an object 6-10in from subject’s face and have them read few words from object
how does size of pupil change as a person switches from looking at distance object to near object
pupil constricted to direct light waves from close object to fovea (accommodation)
what is convergence?
medial rotation of eyeballs as an object moves closer to us, allowing light rays to strike same points on both retinas
describe procedure for testing convergence reflex
- have subject stare at far wall for 1min
- tester observes diameter of subject’s pupils from front w/o blocking subject’s view
- while observing pupil size, tester holds a pencil 6-10in from subject’s face
describe the path soundwaves take through eye
external acoustic meatus → tympanic membrane → auditory ossicle → vestibular window
what happens after sound waves travel to vestibular window?
perilymph and endolymph in cochlea move, resulting pressure waves cause microvilli on hair cells to bend, triggering receptor potential
nerve impulses travel via cochlear branch of CN (VIII) to thalamus to be processed and interpreted as sound
what happens to pressure built up inside cochlea?
released via cochlear window into middle ear
what is the auricle?
flap of elastic cartilage, part of external ear
- attached to head by ligaments and muscles
- collects soundwaves and channels them inward
what is the helix?
rim of auricle
what is the lobule?
inferior portion of auricle
what is the external acoustic meatus?
curved tube in temporal bone that leads to middle ear
- directs soundwaves to tympanic membrane
what is the tympanic membrane?
thin, semitransparent partition of fibrous connective tissue btwn external acoustic meatus and middle ear
- vibration from soundwaves to tympanic membrane cause malleus to vibrate
what are the auditory ossicles?
smallest bones of body, joined by synovial joints, transmits and amplifies vibrations from tympanic membrane to vestibular window
what is the malleus?
attached to internal surface of tympanic membrane
- articulates w/ body of incus
what is the incus?
articulates w/ head of stapes
what is the stapes?
fits into vestibular window
what is the vestibular window?
small, membrane-covered opening btwn middle and inner ear where foot plate of stapes fits
what is the cochlear window?
small opening btwn middle and internal ear
- directly inferior to vestibular window
- covered by 2ndary tympanic membrane
what is the eustachian tube?
connects tympanic cavity w/ nasopharynx
- opens during swallowing/yawning
- allows pressure in tympanic cavity to equalize w/ atmospheric pressure
what is the vestibular branch of the vestibulocochlear (VIII) nerve?
contains 1st order sensory neurons and efferent neurons that synapse w/ receptors for equilibrium
what is the cochlear branch of the vestibulocochlear (VIII) nerve?
contains 1st order sensory neurons and motor neurons that synapse w/ inner and outer hair cells on spiral organ for hearing
what are the semicircular ducts?
portions of membranous labyrinth that lie inside the bony semicircular canal, connecting w/ utricle of vestibule
- contains receptors for detecting rotational deceleration/acceleration
what are the semicircular canals?
3 bony channels that contain receptors for equilibrium
what are ampullae?
swollen enlargements at end of each semicircular canal
- contains cristae
what are cristae?
small elevations in ampulla of each semicircular duct
- contains receptors for rotational acceleration/deceleration
what is the cochlea?
winding, cone-shaped tube forming portion of inner ear
- transmits vibrations to spiral organ
what is the cochlear duct?
scala media
membranous cochlea consisting of spirally arranged tube enclosed in cochlea & lying along its outer wall
what is the scala vestibuli?
superior spiral-shaped channel of the bony cochlea
- ends at the vestibular window
what is the scala tympani?
inferior spiral-shaped channel of bony cochlea
- ends at cochlear window
what is the vestibular membrane?
membrane that separates cochlear duct from scala vestibuli
what is the basilar membrane?
membrane in cochlea that separates cochlear duct from scala tympani
- on which spiral organ rests
- bodies of hair cells rest on basilar membrane
what is the spiral organ?
organ of Corti
organ of hearing, consists of hair cells that produce receptor potentials from vibrations, eliciting nerve impulses in cochlear branch of CN VIII
what is the tectorial membrane?
gelatinous membrane projecting over & in contact w/ hair cells of spinal organ
- ends of stereocilia of hair cells embedded in tectorial membrane
what is the vestibule?
small space in bony labyrinth of inner ear, contains utricle
what is the utricle?
two sacs inside membranous labyrinth of vestibule
- contains receptor organs for linear acceleration/deceleration that occurs in head tilt and horizontal direction
what is the saccule?
inferior & smaller of the chambers in the membranous labyrinth inside vestibule of inner ear
- contains receptors for linear acceleration/deceleration that occurs in vertical direction
what is the macula?
small, thickened region on utricle wall & saccule wall
- contains receptors for linear acceleration/deceleration and head tilt
what are otoliths?
calcium carbonate crystals embedded in otholithic membrane, detects linear acceleration/deceleration and head position
Describe procedure for examining structures of outer ear using otoscope
- determine which diameter tip will fit comfortable in subject’s external acoustic meatus
- clean in and out of top w/ alcohol and attach to otoscope handle
- tester holds lit otoscope and inserts tip of otoscope into external acoustic meatus while grasping subject’s upper auricle pulling it up and back
- examine tympanic membrane, noting shape, colour, blood vessels, hair, earwax
- remove and clean tip of otoscope w/ alcohol, ensure light is switched off
describe procedure for testing auditory acuity
- have subject sit in quiet location w/ eyes closed and plug left ear
- tester holds softly ticking clock very close to right ear
- slowly move clock directly away from ear until subject indicated ticking no longer heard
- measure distance at which ticking no longer heard
- repeat w/ other ear
describe the procedure for testing auditory localization
what happens if you cup your hands behind ears to gather sound during the auditory localization test?
sound is resonated, sounds echo-like, background noise reduced, enhancing ability to determine position of sound
describe procedure for testing vertical acceleration/deceleration
going up and down elevator
what are the receptors being tested when going up and down an elevator?
receptors in saccule of vestibule
describe procedure for testing horizontal acceleration/deceleration
have subject stand upright w/ eyes closed
have subject tilt head forward, raising chin up again
what receptors are being tested by tilting head forward and raising chin up?
receptors in utricle of semicircular canal
describe procedure for testing receptors for rotational acceleration/deceleration
multiple rotations (10 turns in 20 seconds)
what happens when you turn multiple times in a short period?
endolymph in semicircular ducts continue to move after subject’s body stops rotation
vertigo and dizziness can occur
what receptors are being tested when turning multiple times in a short period of time?
cristae on ampullae on semicircular ducts
describe function of sensory receptors
they receive external/internal stimuli from environment and transduce them into receptor potentials
what are 3 somatic sensations that are detected by free nerve endings?
- pain
- temperature
- itching
- tickling
what are 3 somatic sensations detected by encapsulated nerve endings?
- pressure
- vibration
- some touch sensations
why might lack of cutaneous receptors be dangerous?
sensations on skin will be gone, reflexes and responses to evasive stimuli will be gone and take longer to happen
several minutes after applying perfume, you notice you cannot smell it anymore. should you apply more?
No, sensory adaptation occurred in only your olfactory receptors, others’ haven’t
what is the sensory limb of the pupillary light reflex?
optic (II) nerve
what is the motor limb of the pupillary light reflex?
parasympathetic fibres of oculomotor (III) nerve
briefly describe the pupillary light reflex test
shine a flashlight into each eye noting the direct and consensual constriction of pupils
what is the swinging flashlight test?
used to test relative sensory pupillary defect
swinging flashlight back and forth btwn the 2 eyes identifies if one pupil has less light perception than the other
describe procedure for swinging flashlight test
shine flashlight at one eye noting size of both pupils, then swing flashlight to other eye
what is the abnormal response to the swinging flashlight test?
if both pupils dilate after flashlight shines on one eye, then that eye has perceives less light stimulus than opposite eye, indicating defect in sensory pathway
what are vergence eye movements?
when eyes move simultaneously inward (convergence) or outward (divergence)
briefly describe the accomodation test
patient is asked to follow an object that is brought from distance to tip of their nose
what happens when a distant object is brought closer?
- eyes converge
- pupils constrict
- lens round up
which areas are the smallest and most dense sensory units found in?
areas w/ the greatest somatosensory cortical representation (the areas of the body that are biggest on the somatosensory homunculus)
- lips
- fingers
