IGCSE›Cambridge IGCSE Biology›Mind mapsSense OrgansCambridge IGCSE Biology: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsSense organsGroups of receptor cellsEyes detect light, ears soundSkin: touch and temperatureNose and tongue: chemicalsEye structuresCornea refracts lightIris controls light enteringLens focuses lightRetina detects lightOptic nerve carries impulses to brainPupil reflexBright light: pupil constrictsDim light: pupil dilatesCircular muscles make pupil smallerRadial muscles make pupil biggerSense organsthe eyeAccommodationNear: ciliary muscles contract, ligaments slack, lens fatterFar: ciliary muscles relax, ligaments taut, lens thinnerRods and conesRods: dim light, no colourCones: colour vision, three typesFovea: densest cones, sharpest visionExam tipsLearn structure-function pairs togetherCircular = constrict, radial = dilateNear object: lens fattens