IGCSE›Oxford AQA IGCSE Biology›Mind mapsThe human nervous systemOxford AQA IGCSE Biology: Mind mapStudy pack PDFAlso for this subtopic:Revision notesFlashcardsSubtopic testCover factsOrganisationCNS: brain and spinal cordPNS: peripheral nervesCerebellum: coordination and balanceMedulla: automatic functionsHypothalamus: homeostasisNeuronesSensory: receptors to CNSRelay: within the CNSMotor: CNS to effectorsNeurotransmitters cross the synaptic cleftReflex arcStimulus → receptor → sensory neurone→ relay neurone → motor neurone→ effector → responseFast, automatic, bypasses the brainNervous systemneurones, reflexes, eyeThe eyeCornea and lens focus light on retinaRods: low light, black and whiteCones: bright light, colourOptic nerve carries image to brainFocus and defectsNear object: ciliary muscles contract, lens thickerDistant object: muscles relax, lens thinnerShort-sighted: concave lens correctsLong-sighted: convex lens correctsExam tipsWrite the reflex arc in exact orderName ciliary muscles and ligamentsSensory neurones carry impulses to the CNS