Bellwork 1. Explain the difference between rods and cones. What happens if someone is missing a certain kind of cone? Answer: Rods work in the dark and see gray tones, shape and movement. Cones see in color and only work in bright light. If someone is missing a certain kind of cones, they will be colorblind (not able to see that specific color. SWBAT describe the structure of the eye. SWBAT explain the pathway of light. SWBAT differentiate between different types of vision. Example
Special Senses The Eye and Vision
Anatomy of the Eye Lens: focuses light entering eye onto the retina When we are young, lens is flexible and clear. As we age it gets hard and opaque causing cataracts Cataracts can eventually cause blindness, can be treated by surgical implant
Anatomy of the Eye Lens divides eye into 2 fluid filled chambers Anterior segment Contains aqueous humor (clear, watery) Posterior segment Contains vitreous humor (gel-like) These fluids maintain intraocular pressure, Glaucoma is the result of high pressure. It can cause pain, vision problems, and blindness.
Pathway of Light When light passes through a substance, it is refracted Refracting power of cornea and humors is constant Lens changes shape to help focus light Ciliary body contracts to change lens More convex = light more bent Ability to focus on close objects is called accomodation
Pathway of Light
Correcting Vision Emmetropia: Correct focus Myopia: Nearsightedness Distant objects are blurry Focus of light in front of retina Happens when - Hyperopia: far sightedness Near objects are blurry Focus of light beyond the retina
Correcting Vision Astigmatism – unequal curvatures in different parts of cornea or lens
Visual Fields Binocular vision – “two-eyed” allows for depth perception because our brain fuses a slightly different image from each eye
Practice Label the parts of the eye on your worksheet. Words to Use: Aqueous humor Choroid Conjunctiva Cornea Iris Lens Optic disc Optic nerve Pupil Retina Sclera Vitreous humor On the back find the word that doesn’t belong and explain why it doesn’t belong. Due Tomorrow! Vocab Due Wednesday!
http://www.aoa.org/patients-and-public/resources-for-teachers/classroom-exercises/activity-sheets/activity-sheet-1-how-the-eyes-work