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Special Senses

Special Senses. Chapter 8. Eye Anatomy. Accessory Structures Eyelids Commissures Palpebral fissure Tarsal gland Lacrimal Apparatus Lacrimal gland Lacrimal canaliculi Lacrimal sac Nasolacrimal duct. Extrinsic Eye Muscles. Layers of the Eyeball. Fibous Layer: Schlera and Cornea

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Special Senses

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  1. Special Senses Chapter 8

  2. Eye Anatomy • Accessory Structures • Eyelids • Commissures • Palpebral fissure • Tarsal gland • Lacrimal Apparatus • Lacrimal gland • Lacrimal canaliculi • Lacrimal sac • Nasolacrimal duct

  3. Extrinsic Eye Muscles

  4. Layers of the Eyeball • Fibous Layer: Schleraand Cornea • Vascular Layer: choroid, ciliary body, ciliaryzonule, iris and pupil • Sensory Layer: retina and pigmented layer

  5. Retina (Neural Layer) • Ganglion cell axons form optic nerve • Bipolar cells • Photoreceptors • Rods=grey tones and dim light, peripheral and night vision • Cones=color, fovea centralis is place of greatest visual acuity

  6. Photoreceptors • Visual Pigment (Rhodopsin) • Opsin + Retinal • Light strikes Rhodopsin causing opsin and retinal to separate • Retinal is converted to vitamin A • Retinal is recombined with opsin in the dark • Different forms of opsin allow us to see color • Red • Green • Blue

  7. Color Blindness • http://colorvisiontesting.com

  8. How do we focus?

  9. Visual Field

  10. Hearing and Equilibrium

  11. Inner Ear • Vestibule =static equilibrium • Cochlea =hearing • Semicircular Canal =dynamic equilibrium

  12. Equilibrium Static Dynamic Positioning when moving Semicirular canals Crista Ampularis Cupula and hair cells Cochlear branch of vestibulocochlear nerve • Positioning a • Maculae • Otolithic membrane • Otoliths • Hair cells • Vesibular branch of vestibulocochlear nerve

  13. Hearing • Cochlea has three membranous chambers • ScalaVestibuli • Scala Media =cochlear duct=spiral organ of corti • Scala Tympani

  14. Cochlear Duct • Stapes causes vibrations in the oval window • Vibrations cause “waves” within fluid of cochlear chambers • Pressure waves cause vestibular and tectorial membranes to move • Movement of tectorial membrane stimulates hair receptors which transmit the signal to the cochlear nerve

  15. Chemical Senses • Olfaction and Gustation detect stimuli dissolved in water • Smell and Taste work together • Combinations of receptors allow us to smell and taste complex substances • Both olfaction and gustation utilize receptors on hair cells

  16. Homeostatic Imbalances • Conjunctivitis • Colorblindness • Nightblindness • Glaucoma • Otitis Media • Deafness • Conduction deafness • Otosclerosis • Sensorineural deafness • Meniere’s Syndrome • Strabismus • Amblyopia • Macular Degeneration

  17. Developmental Aspects • Sense organs are formed early but not all are fully functional at birth • Taste and hearing are fully functional in the womb • Fetuses develop taste and sound preferences while developing • Smell is functional at birth but has a learned component • Vision is not fully functional until about 5 years of age

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