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The Eye

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The Eye

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    1. The Eye Photoreception Accessory Structures Eyebrows Eyelids Lacrimal caruncle Sebaceous & sweat glands; Sandmans eye sand. Epicanthic fold Eyelashes Innervated with many nerves. Conjuctivatransparent membraneover eyelids and sclera. Important in lubrication of the eye. ConjuctivitisPinkeye. Lacrimal Apparatus Lacrimal gland Nasolacrimal duct Tears contain antibodies and lysozyme.

    4. The Human Eye Corneacontains many nerve endings.transplantation and repair. pupil iris Lens--convex suspensory ligaments ciliary bodies Extrinsic muscles retina cones and rods optic nerve Choroid coatWhy is it dark colored?

    5. Human Eye

    6. Light and Image Formation Electromagnetic Radiation Visible light Reflection Refraction Real image Convex lens Upside down and reversed form left to right.

    7. Image Formation Focal point Focal length Retina Photoreceptors Optic disc Blind spot Optic nerve Rods cones Macula lutea Fovea centralis Forms a pathway for light to get to the photoreceptors. Most cones are in the fovea. This is where important area for hard focusing. Small portion of our field of view.

    8. Human Eye Defects Myopia Causes Eye too long or lens too convex Effects Correctionconcave lens. Hyperopia Causes Eye too short or lens too flat Effects Correctionconvex lens. Presbyopia

    9. Myopia

    10. Hyperopia

    11. Eye Disorders Diplopiamovements of the extrinsic muscles of the 2 eyes are not coordinated. Leads to double vision. Strabismuscross-eyed Affected eye rotates either medially or laterally. Treatments and effects. Retinal Detachment Glaucomaexcessive aqueous humorIntraocular pressure. Cataractclouding of the lens. May be caused by sunlight, diabetes, smoking, vitamin deficiencies,, etc Astigmatism Color blindness Night blindness

    12. Visual Pathways to the Brain From the retina, visual impulses travel to: Optic nerve Optic chiasma Optic tracts Thalamus Optic radiation tract Primary visual cortex in the optic lobe.

    13. Hearing What is sound? Wavelength Frequency Pitch Intensity Amplitude Loudness Decibels Above 90 db is dangerous Hearing range20 to 20000 Hz

    14. Hearing Mechanoreceptors Fluids Outer, middle, and inner ear Outer ear Pinna or auricle Are bigger ears better? External auditory canal Ceruminous glands Tympanic membrane Middle Ear Pharyngotympanic tube Eustachian tube How does this structure function? Ossicles Malleus, incus, stapes Malleus is attached to the eardrum. Stapes is attached to the oval window of the inner ear. Sound amplification

    15. Hearing Transmit vibrations of the eardrum to the middle ear. Inner ear Bony labyrinth Semicircular canals Vestibule Cochlea Membranous labyrinth Inside the bony labyrinth Filled with fluid Vestibuleoval window is attached to this structure. Contains equilibrium receptors. Semicircular canalsposter and lateral to the vestibule. Ampullaequilibrium receptors.

    18. Hearing Cochleaanterior to the vestibule. Cochlear duct Basilar membrane Organ of Corti Hair cells Cochlear nerve Thalamus Auditory cortex in temporal lobes Disorders of the Ear Otitis Media Deafness Conduction Deafness Otosclerosisstapes becomes fused to oval window. Sensorineural deafnessdamage to hair cells or neural pathways. Cochlear implants Tinnitus

    19. Equilibrium Importance of head movements. Inputs from the inner ear, eyes, and stretch receptors Vestibular apparatus Vestibulestatic equilibrium Semicircular canalsdynamic equilibrium Maculaerespond to straight line changes in speed and direction, not to rotation Hairs cells Vestibular nerve Respond only to changes in velocity or acceleration.

    20. Equilibrium Crista ampullaris Semicircular canals Respond to rotation Changes in rotation Hair cells To balance centers in the brain stem or the cerebellum Motion sickness Sensory input mismatch

    21. Taste Chemoreceptors Aqueous chemicals Taste buds Most on the tongue Papillaeprojections of the surface of the tongue. Gustatory and taste cellstaste receptors Taste pore Gustatory hairs Replaced every 7 to 10 daystaste buds 4 basic tastes Sweet, salty, bitter, sour Sweetsugars, alcohols, amino acids Souracids Saltymetal ions Bitteralkaloids; poisons

    23. Taste Impulses travel from taste receptors to: Either the facial nerve or glossopharyngeal nerve or vagus nerve to: Medulla to: Thalamus to: Gustatory cortex in the parietal lobes There are also branches to the limbic system Triggers digestive reflexes.

    24. Smell Olfaction Olfactory epithelium in the roof of the nasal cavity. Olfactory receptor cells Olfactory cilia Mucous covered Life span of 60 days. Olfactory receptors to: Olfactory nerves to: Olfactory bulbs to: Olfactory tract to: Thalamus to the olfactory cortex and the frontal lobe and to the hypothalamus, amygdala, and other parts of the limbic system. Anosmias Zinc deficiencies

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