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A&P.eyes.c15
A&P.eyes.chap15
| Question | Answer |
|---|---|
| eyelids | palpebrae |
| space between the two eyelids | palpebrae fissure |
| angles where eyelids join | canthi (corners) |
| canthus beside nose (or medial canthus) | caruncle "mound of tissue" - contain sweat and sebaceous glands |
| conjunctiva (2 kinds) | palpebral conjunctiva - covers inner surface of eyelids 2. bulbar conjunctiva - covers anterior white surface of the eye |
| where do the palpebrae & bulbar conjunctiva meet? | called the superior (upper eyelid) and infereior (lower eyelid) conjunctival fornices |
| conjunctivits - pinkeye - inflammation | |
| lacrimal apparatus | lacrimal gland above eye - washes eye toward nose - parasympathetic fibers from FACIAL NERVE VII - lucky 7 - you'll cry when you hit 7!! |
| how many tears per day? | 1 mL- tears are water, salts, mucus, & lysozyme (kills bacteria) |
| where do tears go? | most evaporate; rest collected in lacrimal canalicul (canals) & go through lacrimal sac to nasolacrimal duct |
| extrinsic muscles - 6 in all | superior, inferior, medial and lateral RECTUS (straight) muscles - controled by Oculomotor nerve III |
| superior muscles | it's so superior - it needs a pulley - the trochlear nerve controls Cranial nerve IV - |
| lateral rectus muscle | innervated by abducent nerve (VI) |
| three tunics of eye | fibrous tunic (sclera, cornea) the vascular tunic (choroid, ciliary body and iris and 3. nervous tunic - retina |
| sclera | dense collagenous connective tissue with elastic fibers |
| what is connected to the sclera? | the bulbar conjunctiva is loosely connected to the sclera |
| cornea IMPORTANT | avascular - transparent structure - is a lens that bends light - connective tissue - few large collagen fibers and low water content |
| vascular tunic | short ciliar arteries - pierce the sclera in a cirlce around the optic nerve |
| ophthalmic artery | branc of internal carotid artery |
| what supplies blood to the sclera? | the choroid (means membrane) eye is surround by thin layer of blood vessels |
| ciliary body is continous with | choroid |
| iris is attached to | ciliary body |
| ciliary body consists of | outer ciliary ring - inner group of ciliary processes |
| how are the ciliary processes attached to the lens | by suspensory ligaments |
| ciliary muscles | change shape of lens to focus |
| iris consists of two muscle groups | a circular group called the sphincter pupillae (innervated by oculomotor nerve III) - and a radial group called the dilator pupillae (radiator-dilator) |
| retina | pigmented retina - melanin - black background (does not diffuse light) |
| sensory retina 3 layers | 3 layers of neurons: photoreceptor; bipolar and ganglionic |
| plexiform layers | the three layers synapse with each other |
| rods | rhodopsin - noncolor, low light - over most of retina - but not fovea centralis |
| cone | iodopsin (eye drops of color)- color vision; visual acuity - numerous in fovea |
| fovea centralis | 35,000 cones and no rods |
| 120 million rods | 10-20 times more plentiful |
| what is the general area where light is focused? | macula lutea |
| what is the small area where light is focused? | fovea centralis |
| what is the white spot in the eye? | the optic disk - no photoreceptor cells- blind spot |
| three chambers of the eye | anterior, posterior (with aqueous ) and vitreous with gell |
| aqueous humor is | 1. a blood filtrate that is retunred to circulation via the CANAL OF SCHLEMM (also called the scleral venous sinus) |
| what happens if canal of schlemm is blocked? | glaucoma - abnormal increas in introcular pressure |
| lens is | BICONVEX - with greatest convexity in the back (posterior) side - |
| how does eye see? | light striking retina is converted into action potentials that are relayed to the brain |
| convex lens focuses light | light tends to converge on a point |
| reflection | light rays bounce off an object that is not transparrent |
| emmetropia | "measure" lens normal focus |
| far point of vision | point at which lens does not have to thicken to focusing |
| what happens when object is brought closer than 20 feet to the eye (3 things) | 1. accommodation - objjects are brought closer to eye, so lens is made thicker to focus 2. pupil constriction - depth of focus 3. convergence-both eyes watch moving object |