Test 3 Review Chapter 8 Eyelids help circulate fluids over eye by blinking reflex closing for protection Eyelashes trap debris prevent large particle from entering eye Glands located between the eyelashes tarsal glands modified sebaceous glands – produce an oily secretion that lubricates the eye ciliary glands – modified sweat glands Conjunctiva membrane that lines the eyelids connects to the outer surface of the eye secretes mucus to lubricate the eye and keep it moist Lacrimal apparatus = lacrimal glands and ducts lacrimal gland – produces lacrimal fluid; situated on lateral aspect of each eye excretory ducts – fluid produced in lacrimal gland enters eye laterally via ducts lacrimal canaliculi – drain lacrimal fluid from eyes medially lacrimal sac – provides passage of lacrimal fluid towards nasal cavity nasolacrimal duct – empties lacrimal fluid into the nasal cavity Function of the lacrimal apparatus protects moistens, and lubricates the eye empties into the nasal cavity Extrinsic eye muscles six muscles attach to the outer surface of the eye produce eye movements o lateral rectus; moves eye laterally; VI (abducens) o medial rectus; moves eye medially; III (oculomotor) o superior rectus; elevates eye and turns it medially; III (oculomotor) o inferior rectus; depresses eye and turns it medially; III (oculomotor) o inferior oblique; elevates eye and turns it laterally; III (oculomotor) o superior oblique; depresses eye and turns it laterally; IV (trochlear) Structure of the eye: the fibrous layer sclera o white connective tissue layer o seen anteriorly as the “white of the eye” cornea o transparent, anterior portion of sclera o allows for light to pass through o repairs itself easily
o the only human tissue that can be transplanted without fear of rejection Structure of the eye: vascular layer choroid is a blood-rich nutritive layer in the posterior of the eye o iridescent dark pigments prevent light from scattering modified anteriorly into two intrinsic muscles: o 1.) ciliary body – smooth muscle attached to lens by ciliary zonule (suspensory ligament) o 2.) iris – smooth muscle that regulates amount of light entering the eye pigmented layer that gives eye color pupil – rounded opening in the iris Structure of the eye: sensory layer retina contains two layers o 1.) outer pigmented layer absorbs light, prevents it from scattering o 2.) inner neural layer contains receptor cells (photoreceptors) rods cones fovea centralis – area of greatest visual activity signals leave the retina toward the brain through the optic nerve optic disc (blind spot) is where the optic nerve leaves the eyeball o no receptors for vision – cannot see images focused on the optic disc cones o allow for detailed color vision o densest in the center of the retina o fovea centralis – lateral to blind spot area of the retina with only cones
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