Sensation --> stimulation of sense organs
perception --> the organization of the sensory inputs.
THE VISUAL SYSTEM:
• the eye channels light to the neural tissue - retina
• light enters the system through a transparent window. - cornea
• the cornea and a crystalline lens behind it form an upside down image of objects
on the retina.
• lens --> transparent eye structure that focuses light ray falling on the retina.
• nearsightedness - close objects are clear, far objects are blurry.
• the eye can adjust how much light reaches retina - iris (colour part of the eye) -
• the iris surrounds the pupil (dark circle)
• pupil --> helps control the amount of light passing into the eye.
• when the pupil constricts it lets less light into the eye - sharper image
• when the pupil dilates it lets more light into the eye - less sharp of image.
• saccades --> the movement of the eye.
• images seen by the eye appear upside down on the retina.
• retina --> neural tissue that lines the inside back surface of the eye and it absorbs
light, processes images and sends visual info to brain.
• the axons that run from the retina to the brain meet at a point called the optic
• optic disk --> hole in the retina where the optic nerve fibres exit the eye.
• because its a whole you cannot see the image that falls into it. - blind spot.
• the retina contains 2 types of receptors - cones and rods.
• cones --> play a keyhole in daylight vision and colour vision.
• fovea --> tiny spot in the cents of the retina that contains only cones.
• rods --> play a key role in night vision and peripheral vision.
• they are more sensitive than cones, to dim light.