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Equilibrium. The equilibrium receptors are located in the There are 2 types of equilibrium: Static Equilibrium – Dynamic Equilibrium – . Static Equilibrium. Maculae – Composed of Otoliths – As the head moves, the otoliths
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Equilibrium • The equilibrium receptors are located in the • There are 2 types of equilibrium: • Static Equilibrium – • Dynamic Equilibrium –
Static Equilibrium • Maculae – • Composed of • Otoliths – • As the head moves, the otoliths • The hair cells send the electrical signal to the cerebellum to make the body aware of the head’s position
Dynamic Equilibrium • Semicircular canals are arranged in the • Crista ampullaris - • Contain hair cells covered by a gel-like cap called the • As the head moves, the
Accessory/External Structures of the Eye • Eyelid & eyelashes – • Tarsal glands – • Located on • Conjunctiva - • Conjuctivitis
Lacrimal Apparatus Lacrimal gland • Lacrimal gland • Flow of Tears: Canals Lacrimal sac Nasolacrimalduct
Extrinsic eye muscles • Usually coordinate movement in both eyes S S M Lateral rectus (cut) I I
Internal Structures of the Eyeball • The wall of the eyeball is composed of 3 layers:
Outermost Fibrous Layer Sclera Cornea • Sclera • Cornea • Can be transplanted without fear of rejection
Lasik Surgery • Procedure that • Process: • A flap of the cornea is cut and pulled back • A “cool” laser destroys tissue of the cornea to shape it for the best focusing power • Flap is placed back over pupil Animation of Lasik Surgery: http://www.youtube.com/watch?feature=fvwp&NR=1&v=Bb8bnjnEM00 Video of actual Lasik Surgery: http://www.youtube.com/watch?v=O4kDC4sZ5Jg
Middle Vascular Layer Choroid Iris • Choroid • Modified at front into two structures: • Ciliary Body - • Iris - Pupil Ciliary Body
Constriction/Dilation of Pupil • Dim light • Bright light Radially arranged Smooth muscle fibers Parasympathetic motor nerve fiber Sympathetic motor nerve fiber Circularly arranged smooth muscle fibers Pupil In bright light In dim light In normal light
Inner Sensory Layer Retina • Retina • Does not contain photoreceptor cells, thus known as the “blind spot” Optic Nerve Optic Disc (blind spot)
Photoreceptor Cells: Rods & Cones Cones Rods • Rods • Cones • Located near blind spot Rod Cone (c)
Cones • Cone Sensitivity (c)
Lens & Humors Lens • The lens divides the eye into two segments: • Area anterior to lens contains a • Area posterior to lens contains a Aqueous Humor Vitreous Humor
Cataracts • Causes: • Symptoms: • Eventually causes blindness in affected eye • Treatment: Same photo viewed with normal vision and vision with a cataract
Glaucoma • Normally, • Glaucoma is the result • Symptoms: • Treatment:
h. a. i. k. b. l. c. d. m. e. f. g. n.