The Eye and Sight

Orbital Cavity– Overview Structures Eye Eye Lids Lacrimal Apparatus Extrinsic Muscles Functions vision protection lubrication, kill bacteria eye movement and focus

Eye Structure Regions of the eye Outer Layer Inner Layer Anterior Cavity Ciliary Body Posterior Cavity

Eye Regions – Outer Layer Structures Functions Cornea (transparent tissue) Sclera (white tissue) Optic Nerve Protection, focus light entering the eye Protection, site of attachment of extrinsic muscles Carry impulses from the eye to the brain

Eye Regions – Anterior Cavity Structures Functions Aqueous Humor Iris Pupil Transports nutrients, maintains eye shape Controls amount of light entering the eye Allows light to enter the eye pupil contraction and dilation video

Eye Regions – Ciliary Body Structures Functions Lens Suspensory Ligaments and Ciliary Muscles Focus light entering the eye Hold lens and adjust its shape video of ciliary body changing lens shape

Eye Regions – Posterior Cavity Structures Functions Vitreous Humor Retina (cones and rods) Choroid Coat Optic Disk Maintain eye shape Receive light and convert it into nerve impulses Nourish the retina, absorb light Point of attachment of retina and optic nerve

Vision– Light Refraction Light waves change speed and direction as they pass through media of different optical densities Refraction: bending of light waves as they pass through a lens.

Vision- Pathways Object reflects light Light through aqueous humor Cornea refracts light Light focused on the retina. Photoreceptors convert light into nerve impulse Iris adjusts amount of light entering the eye. Light enters through the pupil. Light through vitreous humor Ciliary body adjusts lens shape. Lens refracts light

Visual Nerve Pathways Nerve impulses transmitted by the optic nerve Cross over at the optic chiasma Carried to the visual cortex in the occipital lobe visual cortex interprets impulse as image: sight!

Vision: Photoreceptors Photoreceptors on the retina include: Cones: sensitive to different wavelengths of light. Allow color vision. Rods: sensitive to light/dark. Allow black and white vision and night vision.