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A&P 1
(5) Vision
| Question | Answer |
|---|---|
| eyeball is surrounded by... | adipose |
| lacrimal apparatus includes | lacrimal gland and lacrimal ducts |
| lacrimal gland is located in | eye socket superior and lateral to eye |
| the lacrimal gland produces | tears (for flushing) |
| what do tears do | moisten and lubricate surface of eye |
| what do tears contain | lysozyme: enzyme that digests bacterial cell walls |
| what controls lacrimal gland secretions | parasympathetic division (ACH on muscarinic receptors on the lacrimal gland) |
| lacrimal ducts | convey tears that travel across to medial part of eye to drain into ductile system that empties tears into nose |
| what are the extrinsic eye muscles | 4 rectus muscles and 2 oblique muscles |
| what are the 4 rectus muscles | superior, inferior, lateral, medial |
| where are the rectus muscles originated from | optic foramen in sphenoid |
| what nerve controls the rectus muscles | oculomotor (NOT LATERAL RECTUS) |
| what nerve controls lateral rectus | abducens nerve |
| what are the 2 oblique muscles | superior, inferior |
| superior oblique origin | optic foramen in sphenoid |
| what does the superior oblique do | moves eye down and lateral |
| what nerve supplies the superior oblique | trochlear nerve |
| where is the origin of the inferior oblique | on maxilla |
| what does the inferior oblique do | moves eye up and laterally |
| what nerve supplies the inferior oblique | oculomotor nerve |
| the conjunctivital membrane | - transparent mucous membrane lines eyelid and covers anterior white of eye - has goblet cells - lubricates and protects anterior surface of eye |
| conjunctivitis | inflammation of the conjunctiva (pinkeye) |
| sclera | white of eye, tough outermost layer |
| the sclera is where... | extrinsic eye muscles have their insertion |
| the anterior extension of sclera is | the cornea |
| cornea | - lens that refracts light and handles 3/4 of focusing capacity of eye |
| scleral venous sinus | encircles border of cornea, absorbs aqueous humor from anterior chamber into blood |
| glaucoma | blockage of sclera venous sinus, can cause blindness due to fluid buildup compressing and damaging neurons in back of eye (common after 35) |
| corneal opacity | cornea losers its clarity |
| the choroid | middle vascular layer, provides nutrition to other layers |
| the choroid has... | melanin to prevent internal reflection |
| the anterior extension of the choroid is the | ciliary body |
| the ciliary body includes | the ciliary muscle and the ciliary process |
| the ciliary muscles attach to and control the shape of lens via | suspensory ligaments |
| the ciliary muscles is an effector for the | accommodation reflex: changes shape of lens to adjust when looking at different distances |
| when looking in distance, lens has to... | flatten |
| flattening of lens is the... | relaxation of ciliary muscle from sympathetic NS (NT: NE on beta) |
| when looking close, lens has to... | become rounder |
| rounding of lens is.. | contraction of ciliary muscle from parasympathetic NS (NT: ACH on muscarinic) |
| near point | when ciliary muscle has fully contracted and no further accommodation is possible |
| stimulation for accommodation reflex is due to an ____ ____ in primary visual cortex | unclear image |
| ciliary process | secretes aqueous humor into the anterior chamber |
| what does aqueous humor provide | nutrition and support for tissue in anterior eye |
| iris | - regulates light entering posterior chamber of eye through pupil - plays role in formation of clear images |
| what does the iris consist of | sphincter pupillae muscle, dilator pupillae muscle |
| when looking at distant object (or in dark environment) pupil needs to be... | dilated (contraction of dilator pupillae muscle by sympathetic NS- NT: NE on alpha to enlarge pupil) |
| when looking at close object (or in bright environment) pupil needs to... | constrict (contraction of sphincter pupillae muscle from parasympathetic NS- NT: ACH on muscarinic to constricts pupil) |
| the lens | - composed of crystallin - contributes to focusing light rays on retina - only restrictive media that can change its effect on bending of light rays |
| presbyopia | stiffening of lens (inability to see close) |
| cataracts | clouding of lens |
| phacosmulsification | ultrasound extraction of lens followed by an intraocular lens implant |
| vitreous humor | - gelatinous, clear CT that fills posterior chamber of eye - maintains shape of eye, holds retina and lens in place - formed during embryonic life - contributes to focusing of light rays |
| the retina | lines posterior chamber of eye |
| what does the retina contain | photoreceptors (rods and cones), and 2 more layers of neurons (bipolar and ganglion cells) |
| cones | respond to bright light via pigments of retinal and 1 of 3 photopsin |
| what are the 3 photopsin | red, blue, green |
| where are cones concentrated in | fovea centralis, pit in the macula lutea |
| true or false: cones provide high acuity due to 1:1 ration between cones and bipolar cells | true |
| rods | respond to dim light via the pigment rhodopsin |
| what is vitamin A required for | synthesis of rhodopsin |
| where are rods concentrated in | peripheral portion of retina |
| true or false: rods have low acuity due to 50:1 ratio with single bipolar cell | true |
| true or false: rods deal with shades of grey | true |
| bipolar cells | - synapse with photoreceptors - transmit a signal to ganglion cells |
| ganglion cells | generate action potentials in response to bipolar cells |
| what do axons of ganglion cells form | optic nerve + ultimately synapse in thalamus |
| what is the optic disc | where optic nerve exits from back of eye |
| blind spot | where no rods/cones are present ("filling in" occurs) |
| when no light, rods + cones will be... | "on". Na and Ca channels open causing depolarization and release the inhibitory NT glutamate |
| in light, rods and cones will be... | "off". pigments break apart, causing closure of Na and Ca channels causing hyperpolarization to stop releasing glutamate |
| dark adaptation | - when moving from bright to dim light, surroundings appear pitch black - cones stop functioning - rhodopsin of rods takes 20-45 min to reform pigments in dim light for vision |
| light adaptation | - when moving from dim to bright light, surroundings appear extremely bright - rods stop functioning, cones provide vision in minutes |
Created by:
katiew0