Lecture 23 -- NS IX -- Sensory Organs II Flashcards
LO1: sequence the events of sound detection:
1) auricle
2) auditory canal
3) tympanic membrane (eardrum)
4) malleus
5) incus
6) stapes
7) oval window
8) cochlea
LO2: state the role of outer ear structures in sound transmission
list the 3 structures of the outer ear in order:
1) auricle
2) auditory canal
3) tympanic membrane (eardrum)
LO2: state the role of outer ear structures in sound transmission
what is auricle function?
directs sound into auditory canal
LO2: state the role of outer ear structures in sound transmission
what is auditory canal function?
earwax (cerumen) secretion
earwax helps clean and lubricate ear and prevent entry of bacteria
LO2: state the role of outer ear structures in sound transmission
what is tympanic membrane (eardrum) function?
vibrates in response to sound wave
LO3: state the role of middle ear structures in sound transmission
list the 4 structures of the middle ear:
4) malleus
5) incus
6) stapes
7) oval window
LO3: state the role of middle ear structures in sound transmission
what is the function of malleus, incus, stapes, and oval window?
what is the malleus, incus, and stapes collectively referred to as?
vibrations from tympanic membrane get carried to oval window
increases pressure of sound waves before reaching inner ear
ossicles
LO3: state the role of middle ear structures in sound transmission
why do we need to increase pressure of sound waves before reaching inner ear?
inner ear consists of liquid –> vibrations must transfer into liquid
vibrating liquid is hard –> need a lot of pressure to have adequate vibrations
LO3: state the role of middle ear structures in sound transmission
how do middle ear muscles attenuate sound levels by dampening vibration of the ossicular chain?
stapedius –> stiffens attachment of stapes to oval window of cochlea
tensor tympani –> pulls on malleus medially, increases tension of tympanic mb
LO4: differentiate the bony labyrinth from the membranous labyrinth. Where are the perilymph and endolymph?
what is the structure of the inner ear and what is special about it?
cochlea – contains the organ for hearing
LO4: differentiate the bony labyrinth from the membranous labyrinth. Where are the perilymph and endolymph?
bony labyrinth vs membranous labyrinth:
bony labyrinth –> temporal bone passages that house the inner ear
membranous labyrinth –> continuous system of ducts filled w/ endolymph
LO4: differentiate the bony labyrinth from the membranous labyrinth. Where are the perilymph and endolymph?
what does the bony labyrinth contain and what is special about it?
what fluid fills the bony labyrinth?
semicircular canal –> regulates equilibrium
cochlea – contains the organ for hearing
perilymph –> CSF
LO4: differentiate the bony labyrinth from the membranous labyrinth. Where are the perilymph and endolymph?
what does the membranous labyrinth contain and what is special about it?
what fluid fills the membranous labyrinth?
semicircular ducts
cochlear duct
endolymph –> intracellular fluid
LO4: differentiate the bony labyrinth from the membranous labyrinth. Where are the perilymph and endolymph?
perilymph vs. endolymph
perilymph –> fills bony labyrinth, made of CSF
endolymph –> fills membranous labyrinth, made of intracellular fluid
LO5: identify the structures of the cochlea:
it has ___ ___ chambers separated by ___
3 fluid-filled chambers separated by membranes
LO5: identify the structures of the cochlea:
how many chambers of the cochlea?
what are the chambers filled with?
what are the chambers separated by?
3 fluid-filled chambers separated by membranes
LO5: identify the structures of the cochlea:
what are the 3 cochlear chambers and what are they filled with?
top –> scala vestibuli –> filled w/ perilymph
middle –> scala media (cochlear duct) –> filled w/ endolymph
bottom –> scala tympani –> filled w/ perilymph
LO5: identify the structures of the cochlea:
what are the 3 membranes of the cochlea?
where are they located?
what are their functions?
vestibular membrane – separates off scala vestibuli
- separates endolymph-perilymph and helps to maintain a chemical difference b/n them
tectorial membrane – located above Organ of Corti
basilar membrane – separates off scala tympani, supports the Organ of Corti
LO5: identify the structures of the cochlea:
what is the Organ of Corti?
where is it located?
what is its function?
Organ of Corti == spiral organ
located w/in the cochlear duct, supported on the basilar mb
the receptor organ for hearing
LO6: describe the Organ of Corti:
what is the Organ of Corti?
a sensory epithelium
LO6: describe the Organ of Corti:
what kind of hairs are in the Organ of Corti?
describe the function of the outer cochlear hair cells
outer and inner hairs
receive descending inputs from the brain to assist w/ the modulation of inner hair cell function
LO7: explain how the cochlear hair cells transduce sound-evoked mechanical vibrations into electrical signals that are then relayed to the brain:
1) (cochlea contains liquid). When stapes hits cochlea, liquid in cochlea starts vibrating
2) specialized cells in cochlea convert vibrations into electrical signals –> sent to brain
3) cochlear hair cells (mechanoreceptors in auditory system) will move
4) for both types of cochlear hair cells (IHC, OHC) –> the mechanical bending of stereo cilia opens potassium channels at tips of stereo cilia that allow depolarization of cells
LO7: explain how the cochlear hair cells transduce sound-evoked mechanical vibrations into electrical signals that are then relayed to the brain:
describe mechanotransduction in the hair cell:
what happens in:
- upward movement of basilar mb
- positive mechanical deformation
1) mechanical deformation
–> hair bundle moves toward longer stereovilli
–> opens channels at the tips of the stereovilli
–> allows K+ influx
–> leads to depolarization
2) depolarization activates voltage-sensitive Ca2+ channels
–> causes release of synaptic vesicles
–> stimulation of accompanying sensory neuron
LO7: explain how the cochlear hair cells transduce sound-evoked mechanical vibrations into electrical signals that are then relayed to the brain:
describe mechanotransduction in the hair cell:
what happens in:
- downward movement of basilar mb
- negative mechanical deformation
1) hair bends away from longer stereovilli
–> channels close
–> hyperpolarization
LO8: sequence the auditory projection pathway:
name the 7 steps:
1) stimulation of hair cells activates sensory neurons
2) info carried on cochlear nerve of CN-8 (vestibulocochlear)
3) cochlear nuclei (medulla)
- each ear sends fibers to both sides of the medulla
4) superior olivary nucleus (pons)
- binaural hearing – identify direction of sound source
5) inferior colliculus
- helps locate origin of a sound in space
6) medial geniculate nucleus (on thalamus)
7) auditory cortex (in temporal lobe)
- conscious perception of sound
LO9: list components of vestibular apparatus:
vestibular apparatus maintains ___ and ___ of the body’s ___ ___
consists of:
maintains balance and awareness of body’s spatial orientation
- 3 semicircular ducts
- 2 chambers (otolith organs) –> utricle and saccule
LO10: indicate the functions of the utricle and saccule:
what are they reponsible for? what do they sense?
responsible for static equilibrium
sense head positions
sense linear acceleration
LO10: indicate the functions of the utricle and saccule:
what do the utricle and saccule contain?
utricle and saccule –> horizontal or vertical?
contain a sensory epithelium –> macula
utricle –> horizontal
saccule –> vertical
LO11: describe the macula:
otoliths – protein-calcium carbonate granules
- add weight to the layer, pulling it down w/ gravity
hair cells are connected to nerve fibers that combine to form the vestibular nerve
LO12: analyze how the macula utriculi detect the tilt of the head:
utricle detects ___ and head-tilts in the ___ plane
saccule detects ___ and head-tilts in the ___ plane
linear accelerations
head-tilts in horizontal plane
linear accelerations
head-tilts in vertical plane
LO12: analyze how the macula utriculi detect the tilt of the head:
what happens when head is erect?
gelatinous layer bears down evenly on utricle
–> cilia remains straight
–> no signals generated
LO12: analyze how the macula utriculi detect the tilt of the head:
what happens when head is tilted?
gelatinous layer beards down unevenly on utricle
–> bends stereo cilia
–> stimulates hair cells
LO13: what is the ampulla?
what is it?
where is it located?
what does it contain?
a bulbous expansion at the base of each semicircular canal
houses the sensory epithelium (crista) that contains the hair cells
LO14: which type of movement does the semicircular ducts and ampulla detect?
rotational movement (angular acceleration)
rotation of head in different planes – stimulates a different duct
movement of endolymph thru the duct (caused by rotation of head) will move the stereocilia in the hair cells of the ampulla
LO14: which type of movement does the semicircular ducts and ampulla detect?
what is the sensory receptors of the vestibular system?
hair cells
LO15: sequence the path that tears follow from the lacrimal gland to the nostril
9 steps:
1) lacrimal gland
2) ducts
3) lacrimal punctum
4) lacrimal canaliculus
5) lacrimal sac
6) nasolacrimal duct
7) inferior meatus of nasal cavity –> (lots of tears = runny nose)
8) nostril
9) throat –> swallowed
LO15: sequence the path that tears follow from the lacrimal gland to the nostril
what is function of tears?
cleanse and lubricate the eye surface
deliver oxygen and nutrients to conjunctiva
contain lysozyme (protect from infection)
LO16: differentiate the aqueous humor from the vitreous humor
together, the optical components of the eye are transparent elements that ___ light rays, ___ (___) them, and ___ images on the ___
admit
bend (refract)
focus
retina
LO16: differentiate the aqueous humor from the vitreous humor
what kind of substance?
aqueous humor vs. vitreous humor
aqueous –> water-like fluid
vitreous –> gel-like substance
LO16: differentiate the aqueous humor from the vitreous humor
function?
aqueous humor vs. vitreous humor
aqueous:
- flows from posterior chamber to anterior chamber
- provides nutrients for cornea and lens
vitreous:
- maintain round shape of eye
- vision clarity –> it is clear –> light is able to pass thru to reach retina
LO16: differentiate the aqueous humor from the vitreous humor
where are they located?
aqueous humor vs. vitreous humor
aqueous –> b/n cornea and lens
vitreous –> b/n lens and retina
LO17: describe the components of the 3 layers (tunics) of the eye
what are the 3 layers?
outer –> fibrous layer
middle –> vasculature layer
inner layer –> retina
LO17: describe the components of the 3 layers (tunics) of the eye
what is the outer layer composed of?
outer layer = fibrous layer
consists of sclera (white of eye) and cornea
LO17: describe the components of the 3 layers (tunics) of the eye
describe sclera:
- what layer is it part of?
- what is it composed of?
- what is its function?
outer –> fibrous layer
composed of dense collagenous connective tissue w/ blood vessels and nerves
provides attachment for extrinsic muscles
LO17: describe the components of the 3 layers (tunics) of the eye
describe cornea:
- what layer is it part of?
- what is it composed of?
- what is its function?
outer –> fibrous layer
anterior transparent region of modified sclera
contains stem cells –> regeneration after injury
admits light into eye
pumps Na+ and water out of eye
LO17: describe the components of the 3 layers (tunics) of the eye
middle layer AKA ___
what is the middle layer composed of?
vasculature layer
composed of:
- iris
- ciliary body
- choroid
LO17: describe the components of the 3 layers (tunics) of the eye
what is the iris?
what layer is it part of?
what is its function?
what does it contain?
middle/vasculature layer
adjustable diaphragm –> controls pupil diameter
contains chromatophores –> cells that contain melanin
LO17: describe the components of the 3 layers (tunics) of the eye
what is the ciliary body?
what layer is it part of?
what is its function?
middle/vasculature layer
thickened extension of the choroid
forms a muscular ring around lens
secretes aqueous humor
LO17: describe the components of the 3 layers (tunics) of the eye
what is the choroid?
what layer is it part of?
what is its function?
middle/vasculature layer
made of a lot of blood vessels
provides oxygenation, nourishment, and waste-removal services to the retina
LO17: describe the components of the 3 layers (tunics) of the eye
what are the neural components of the eye?
optic nerve
inner layer (or retina)
LO17: describe the components of the 3 layers (tunics) of the eye
what is the inner layer of the eye?
retina
LO18: sequence light path from cornea to retina, explaining function of each structure:
5 steps:
1) cornea –> admits light and begins refractive process
2) iris –> controls pupil and diameter size –> enlarges and shrinks –> controls amount of light entering eye
3) lens –> shortens and lengthen width to focus light rays
4) vitreous body –> light passes thru gel-like substance
5) retina –> transforms light image into electrical impulses –> carried by optic nerve to brain
LO19: explain the refraction of light by the cornea:
define refraction:
bending of light rays
LO19: explain the refraction of light by the cornea:
the ___ surface is the site of greatest refraction although it also occurs in the lens and elsewhere
cornea
LO19: explain the refraction of light by the cornea:
the cornea’s refractive power bends the light rays in such a way that they pass freely thru the ___
pupil
LO19: explain the refraction of light by the cornea:
the image that passes thru the cornea is ___ and ___
inverted and reversed
LO20: analyze how the iris muscles control pupil diameter in response to dim and bright light:
iris consists of ___ sheets of ___ muscle w/ contrary actions: ___ and ___
together, the circular muscle of the iris is AKA as the ___
2 sheets of smooth muscle
dilation and contraction
circular muscle of iris AKA pupillary constrictor
LO20: analyze how the iris muscles control pupil diameter in response to dim and bright light:
what does iris do in dim light? controlled by what NS fiber?
what does iris do in bright light? controlled by what NS fiber?
dim light –> iris dilates pupil –> admits more light
- controlled by sympathetic nerve fiber
bright light –> iris constricts pupil –> admits less light
- controlled by parasympathetic nerve fiber
LO21: describe the 3 processes involved in the adjustment to close-range vision:
what is the adjustment to close-range vision called?
what does it do?
accommodation reflex AKA near response
brings near objects into focus thru
(1) eye convergence
(2) pupillary constriction
(3) lens thickening
LO21: describe the 3 processes involved in the adjustment to close-range vision:
(1) convergence of eyes
what is a disorder?
eyes rotated inward by medial rectus
orients visual axis of each eye toward object in order to focus image on each fovea
if eyes can’t converge properly –> diplopia
LO21: describe the 3 processes involved in the adjustment to close-range vision:
(2) pupillary constriction
parasympathetic NS causes pupils to constrict –> increases depth of focus and decreases spherical aberration
spherical aberration –> light passing thru periphery of cornea and lens focus at slightly different location –> results in decreased image quality
LO21: describe the 3 processes involved in the adjustment to close-range vision:
(3) accommodation of lens:
what is a disorder?
change in curvature of lens
parasympathetic NS cause ciliary muscles to contract –> causes lens to become thicker –> easier to see near objects
presbyopia –> lens harden at old age and unable to change shape to thicken –> lose ability to see objects clearly at near distance
LO22: define the structure of the fungus (rear) of the eye:
where is the fundus?
inside, back surface of eye
LO22: define the structure of the fungus (rear) of the eye:
what are the 4 structures of the fungus?
(1) optic disc (blind spot)
(2) fovea centralis
(3) macula
(4) retina
LO22: define the structure of the fungus (rear) of the eye:
describe the optic disc (blind spot):
- where is it
- what does it contain?
exact place where optic nerve leaves rear of eye
doesn’t contain photoreceptors –> blind spot
LO22: define the structure of the fungus (rear) of the eye:
describe the fovea centralis
- where is it?
- what does it do?
pit or depression at center of macula
provides greatest visual acuity
LO22: define the structure of the fungus (rear) of the eye:
describe the macula
- where is it?
- what does it do?
pigmented area in center of retina
responsible for:
- central vision
- color vision
- fine detail
LO22: define the structure of the fungus (rear) of the eye:
describe the retina
- where is it?
- what does it contain?
innermost layer of eye
contains photoreceptors
