Which responses occur in the iris of the eye when a person walks from a brightly lit area to a dimly lit area?

14.2.1 Define sense organs as groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicals

14.2.2 Identify the structures of the eye, limited to cornea, iris, pupil, lens, retina, optic nerve and blind spot

14.2.3 Describe the function of each part of the eye, limited to: – cornea – refracts light – iris – controls how much light enters pupil – lens – focuses light onto retina – retina – contains light receptors, some sensitive to light of different colours – optic nerve – carries impulses to the brain

14.2.4 Explain the pupil reflex in terms of light intensity and pupil diameter only

14.2.5 Explain the pupil reflex in terms of light intensity and antagonistic action of circular and radial muscles in the iris

14.2.6 Explain accommodation to view near and distant objects in terms of the contraction and relaxation of the ciliary muscles, tension in the suspensory ligaments, shape of the lens and refraction of light

14.2.7 State the distribution of rods and cones in the retina of a human

14.2.8 Outline the function of rods and cones, limited to greater sensitivity of rods for night vision and three different kinds of cones absorbing light of different colours for colour vision

14.2.9 Identify the position of the fovea