Special Senses Visual Sense

Visual Sense The Eye … Video Clip

Visual Sense Eyes Eyelid Eyelashes Tarsal Glands Conjunctiva Specialized organs designed for vision Eyelid Eyelashes Tarsal Glands Prevents eyelashes from sticking together Lipid secretion Conjunctiva Mucous membrane covering inner surface of eyelid & surface of eye Provides a fluid, which prevents friction

Visual Sense Nasolacrimal Duct Lacrimal Apparatus Lacrimal Puncta Drains tears into nasal cavity Lacrimal Apparatus Produces tears in glands Tears: Nutrients, Oxygen, Antibacterial enzymes (Lysozyme) & lubricants Lacrimal Puncta Pores that drain into medial canthus Lacrimal Canaliculi Collect tears from collect tears from lacrimal puncta Lacrimal Sac Collect tears from lacrimal canaliculi

Eye Anatomy Sclera Cornea 3 Layers: Iris Retina Choroid Pupil Sclera Ciliary body Lens Choroid Retina 3 Layers: Retina Choroid Sclera

Eye Anatomy Video Clip Optic Nerve Optic Disk – Blind Spot Vitreous Humor Aqueous Humor Retina contains photoreceptors: Rods Cones

Gaucoma Pressure builds up May cause damage to the Optic nerve Aqueous humor is not drained effectively …

Eye Anatomy Rods & Cones initiate the Nerve Impulse and send it towards the brain …. Retina Rods: 125 million adapted to night vision No color or detail Cones: 6 million Adapted for day vision Provide color and detail Bipolar cells – synapse with Rods & Cones Ganglion Cells– synapse with Bipolar cells & merge to become optic nerve

Eye Anatomy Bipolar Cells Ganglion Cells Synapse with Rod & Cones Synapse with Bipolar Cells Merge to become Optic Nerve Rods Bipolar Cells Ganglion Cells

Eye Anatomy Macula Fovea centralis Optic disk Concentration of cones Visual image Fovea centralis High concentration of rods Optic disk Passes impulse on to Optic Chiasm

Visual Pigments – How do we actually see? Visual pigments (in rods & cones) change shape when they absorb light Rods -> pigment rhodopsin. 2 Proteins: rods & opsin Rhodopsin changes shape due to light -> action potentials. Cone cells contain other pigment molecules that are similar to rhodopsin.

Visual Pigments Cones have proteins that are able to absorb 3 different wave length: Blue Green Red Combined those proteins give us Color Vision Rhodopsin & similar Proteins are found in disks, which are frequently replaced.

Visual Pigments Disk Cone cell Rhodopsin Rod cell

Review - Eye Anatomy Bipolar Cells Ganglion Cells Video Clip Bipolar Cells Synapse with Rod & Cones Ganglion Cells Synapse with Bipolar Cells Merge to become Optic Nerve Rods Bipolar Cells Optic Nerve Impulse is passed on from Ganglion Cells to Optic Nerve to the Optic Chiasm Ganglion Cells

Optic Chiasm –> 3 D- Vision