What you’ll learn9 learning objectivesChoose one objective for a focused lesson, or study the complete topic.14.2.1Sense organs as groups of receptor• Describe sense organs as groups of receptor cells responding to specific stimuli: light, sound, touch, temperature and chemicalsSyllabus objective14.2.2Structures of the eye• Identify in diagrams and images the structures of the eye, limited to: cornea, iris, pupil, lens, retina, optic nerve and blind spotSyllabus objective14.2.3Function of each part of the eye• Describe the function of each part of the eye, limited to: (a) cornea – refracts light (b) iris – controls how much light enters the pupil (c) lens – focuses light on to the retina (d) retina – contains light receptors, some sensitive to light of different colours (e) optic nerve – carries impulses to the brainSyllabus objective14.2.4Pupil reflex• Explain the pupil reflex, limited to changes in light intensity and pupil diameterSyllabus objective14.2.5Pupil reflex in terms• Explain the pupil reflex in terms of the antagonistic action of circular and radial muscles in the irisSyllabus objective14.2.6Accommodation to view near and distant• 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 lightSyllabus objective14.2.7Distribution of rods and cones• Describe the distribution of rods and cones in the retina of a humanSyllabus objective14.2.8Function of rods and cones• Outline the function of rods and cones, limited to: (a) greater sensitivity of rods for night vision (b) three different kinds of cones, absorbing light of different colours, for colour visionSyllabus objective14.2.9Position of the fovea and state its• Identify in diagrams and images the position of the fovea and state its functionSyllabus objective