Lecture 23 -- NS IX -- Sensory Organs II Flashcards by Jonah Chang

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

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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)

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LO2: state the role of outer ear structures in sound transmission

what is auricle function?

directs sound into auditory canal

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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

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LO2: state the role of outer ear structures in sound transmission

what is tympanic membrane (eardrum) function?

vibrates in response to sound wave

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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

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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

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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

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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

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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

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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

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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

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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

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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

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LO5: identify the structures of the cochlea:

it has ___ ___ chambers separated by ___

3 fluid-filled chambers separated by membranes

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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

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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

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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

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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

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LO6: describe the Organ of Corti:

what is the Organ of Corti?

a sensory epithelium

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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

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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

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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

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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

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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

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Lecture 23 -- NS IX -- Sensory Organs II Flashcards

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