Photoreceptors

Question 1

Rods:

Answer 1

• detect shorter wavelengths (green-blue appear brighter at night)
• 100 million rods in each eye
• majority 20 degrees from centre of retina
• low visual acuity
• night vision (need lower levels of light to stimulate them, work in peripheral vision)
• black and white vision
• responsible for detecting movement
• peripheral vision

Question 2

Cones:

Answer 2

• detect longer wavelengths (yellow- green appear brighter in the day)
• 6.5 million cones in each eye
• Centre of retina
• work best in bright light
• day vision
• colour vision
• visual acuity

Question 3

Visual acuity –

Answer 3

sharpness of vision, ability to detect fine detail

Question 4

Fovea

Answer 4

small, cup-shaped area in the middle of retina that contains only cones (about 50,000 tightly packed), visions is sharpest when lens focuses light on the fovea

Question 5

Rods and peripheral vision –

Answer 5

– the eye maintains a radar-like scan for movement in side vision, using rods’ location on the retina and their sensitivity to movement, as we depend on this ability to effectively move around our environment