Exam #5 Chapter 17 Flashcards
- shade and protect eyes from excessive light and foreign objects
- spread lubricating secretions
palpebrae (eyelids)
- reddish elevations medial to nasal bone
- contains sebaceous and sudoriferous glands
lacrimal caruncle
-thin protective mucous membrane composed of nonkeratinized stratified squamous epithelium with numerous goblet cells
conjunctiva
- passes from the eyelids onto the surface of the eyeball, where it covers the sclera (white of eyeball)
- vascular
- bloodshot eyes
bulbar conjunctiva
- transparent region that forms the outer anterior surface of the eyeball
- curved, helps focus light onto the retina
- receives oxygen from outside air
- admits and bends light
cornea
- modified sebaceous glands
- secrete fluids that keeps eyelids from sticking together
tarsal glands
-thick fold of connective tissue that forms eyelids
tarsal plate
-water, salts, mucus, and lysozyme, a bactericidal enzyme
lacrimal fluid (tears)
-lacrimal glands—>excretory lacrimal ducts—>superior or inferior lacrimal canalículi—>lacrimal sac—>nasolacrimal duct—nasal cavity
flow of tears
-superficial layer of the eyeball and consist of the anterior cornea and posterior sclera
fibrous tunic
- whites of eye, layer of dense connective tissue made of collagen fibers and fibroblasts
- covers entire eyeball except cornea, gives shape, protects inner parts, serves as attachment for extrinsic eye muscles
sclera
- middle layer
- composed of choroid, ciliary body, and iris
vascular tunic
- third and inner tunic of the eyeball
- lines the posterior three-quarters and is the beginning of the visual path-way
- converts light into receptor potentials and nerve impulses
retina
- lines most of the internal surface is the sclera
- vascularized. and produces melanocytes
- melanin absorbs light and prevents light scattering in the eye
choroid
- anterior protein of the vascular tunic
- ciliary processes contain capillaries and secrete aqueous humor
- ciliary muscle alters the shape of the lens for near/far vision
ciliary body
-colored portion of the eye, regulates amount of light entering the eye
iris
- contract the iris (sphincter pupillae) decreasing pupil size
- parasympathetic, bright light
circular muscles
- increase pupil size (dilator pupillae)
- sympathetic, dims to light
radial muscles
- sheet of melanin containing epithelial cells
- absorbs stray light rays
pigmented layer
- sends nerve impulses into axons that form optic nerve
- contains 3 layers of retinal neurons: photoreceptors (rods and cones), bipolar cell layer, and ganglion cell layer
neural (sensory) layer
-black and white vision, in dim light
rods
-color vision, bright light, blue, green, and red
cones
- more medial, site where the optic nerves exits the eye
- blind spot, b/c it has no rods and cones
optic disc
-small, flat yellowish spot, exact center of posterior portion of the eye
mácula lutea
- small depression in the center of the macula lutea, dense region
- contains only cones, area of highest visual acuity
fovea centralis
- photoreceptors (rods & cones)—>bipolar cell layer—>ganglion cell layer—>optic nerve
- light comes in through optic nerve
neural pathway of light
- behind the pupil and iris, within the cavity of the eyeball is the _____
- refracts light
lens
- filled with aqueous humor
- has two chambers, the anterior and posterior
anterior cavity
-lies between the cornea and the iris
anterior chamber
- lies behind the iris and in front of the lens
- sometimes can create floaters you see in eye, also contains vitreous body
- not continuously replaced
posterior chamber
-within vitreous chamber, transparent jellylike substance that holds the retina flush against the choroid, given the retina an even surface for the reception of a clear image
vitreous body
- light traveling from one medium into another if a different density is called _____
- anterior and posterior corneal surfaces and lens refract light
refraction
- ____% of refraction occurs the the cornea
- ____% is the remaining refraction that occurs in the lens which also changes the focus to view near or distant objects
75%
25%
- a surface that curves outward is said to be
- light rays refracted towards each other that will eventually intersect
convex
- if the lens curves inward, it is said to be
- light rays refract away from each other
concave
-_____for near vision, convex surfaces cause the light to converge (rays get closer together)
accommodation
-images produces are _____ and _____, but the brain learns (via interacting with objects) how to coordinate the visual inputs with their actual orientation
upside and reversed
- light converges before the retina, corrected with diverging lens
- light enters to early (nearsightedness)
myopic
- light converges behind retina, corrected with converging lens
- light enters late (farsightedness)
hyperopic
- irregular curvature of the cornea or lens
- image is out of focus or distorted as a result
astigmatism
-clouding of the lens
cataracts
-isn’t a refraction problem, increased intraocular pressure damages optic nerve
glaucoma
- in plasma membranes of outer segments of rods and cones
- absorbs light and undergoes a structural change, leading to receptor potential
photopigment
-single type of photo-pigment in rods is
rhodopsin
- 3 different types are in the retina, blue, green, and red
- creates color vision
cone photopigments
- all photopigments associated with vision contains two parts:
- a glycoprotein called _____
- a derivative of vitamin A called _____
opsin and retinal
-isomerization—>bleaching(trans-retinal separates from opsin)—>conversión(converts trans to cus-retinal)—>regeneration(cis-retinal binds to opsin)
rhodopsin cycle
-the process by which light energy is converted into a receptor potential in the outer segment of a photoreceptor
transduction
- light causes a conformation change in the photopigment
- cGMP is broken down, cGMP-gated channels not open
- less Na+ is allowed in, less NT vesicles bind
**less inhibitory NT’s = positive signal
transduction (light—>signal)
-lateral inhibition of rods and cones and bipolar cells
horizontal cells
-lateral inhibition of bipolar and ganglion
amacrine cells
-optic nerve(II)—>optic chia am—>optic tract—>lateral geniculate nucleus of thalamus—>optic radiation—>primary visual area of cerebral cortex
visual pathway
-the external ear consist off:
auricle
external auditory ear
ear drum
-collects sound waves
auricle
-small hairs and ceruminous glands trap dust and foreign objects
external auditory canal
-transmits sound vibrations to middle ear, eardrum
tympanic membrane
-the middle ear consist of the auditory ossicles called:
malleus (hammer)
incus (anvil)
stapes (stirrup)
-base of the stapes fits in the _____ of the inner ear
oval window
-round window to the inner ear is enclosed by the ______
secondary tympanic membrane
-connects nasopharynx to middle ear to relieve pressure during swallowing and yawning
auditory tube (eustachian tube)
-bony labyrinth (inner ear) has 3 parts:
semicircular ducts
vestibule
cochlea
-the bony labyrinth is lined with periosteum and contains _____ (like CSF), which surrounds the _____
perilymph
membranous labyrinth
-the membranous labyrinth is filled with _____, which has lots of K+
endolymph
-branching of the nerve ______ shows which portion of the inner ear is equilibrium and which is for hearing
vestibulocochlear VIII
- auricle directs sound waves down canal
- sound waves cause eardrum to vibrate (slowly for low-frequency, low pitch)
- vibrations transmitted through ossicles
- vibrations at oval window 20x more vigorous
- fluid pressure waves in perilymph (in scala vestíbuli)
- waves transmitted to scala tympani and eventually round window
- waves in the SV and ST deform the cochlear duct, causing fluid waves
- waves in the endolymph move the hair cells, leading to an impulse
- round window bulges outward towards middle ear (allowing fluid movement)
sound wave pattern
-oval central portion of the bony labyrinth
vestibule
-continuation of the membranous labyrinth into the cochlea, filled with endolymph
cochlea duct
-channel above the cochlear duct, ends at the oval window
scala vestibuli
- the receptors for hearing, inside cochlea
- have inner cells arranged in a single row
- have outer cells arranged in three rows
- _____ of the spinal organ convert a mechanical vibration into a receptor potential
hair cells
- at the apical tip of each hair cell
- long hairlike microvilli arranged in several rows of graded height
stereocilia
-alternating high and low pressure regions traveling in the same direction through some medium(such as air)
sound waves
-______ gated channels are the key in hair cell transduction
mechanically
-partially open channel, small amount of NT
resting hair
- hair cells bend towards the tallest stereocilum
- open channel, high amount of NT
strong depolarized hair cell
- hair cells bend away from tallest stereocilium
- closed channel, no NT
hyperpolarized hair cell
vestibulocochlear nerve VIII-cochlear nuclei (in medulla, some axons may decussate)—>lateral lemincus (on opposite side)—>inferior colliculus(of midbrain)—>superior olivary nucleus—>medical geniculate—>primary auditory area—
auditory pathway
-the utricle and saccule of the vestibule
otolithic organs
-attached to inner walls of both the utricle and the saccule, small thickened region
macula
-layer of dense calcium carbonate crystals
otoliths
- functions are analogous
- movement causes displacement of an accessory structure, which moves ______
hair cells
- gelatinous material, analogous to otoliths
- as head rotates in one direction, they are dragged through endolymph and bent in opposite direction
cupula
- most VC nerve VIII axons go to vestibular nuclei in ______ and ______ (also collects info from other nerves )
- remaining axons go through ______ to cerebellum
medulla and pons
inferior cerebral peduncles
-detects linear acceleration or deceleration that occurs in a horizontal direction and also head tilt
utricle
-detects linear acceleration or deceleration that occur in a vertical direction
saccule
-ganglion cell layer have ______ cells
1st order
-trans-retinal can’t receive _____
light
