Nervous System

Name: __________________ Topic: Nervous System LO:Statetherelationshipbetweenreceptors,thecentralnervoussystemandtheeffectors ● Receptoror senseorgansdetectstimulusandis stimulated, generatingnerveimpulses.● Sensoryneuronetransmitsnerveimpulsesto therelayneuronein thecentralnervous system (CNS)which consists of thebrain/spinalcord.● Beforetransmittingnerveimpulsesalongthe motorneuroneto the effector(muscles/ glands) to carry out the response. LO:Statethatthenervoussystem– brain,spinalcordandnerves,servestoco-ordinate and regulate bodily functions Concepts Summary NotesNan Hua High School Biology 1

Name: __________________ Topic: Nervous System LO:Outlinethe functionsof sensoryneurones,relayneuronesandmotorneurones ● Neurones arenervecellsthatfunctionto transmitnerveimpulses withinthenervous system.● Neurones differ inshapesandsizes.● Basic components of a neurone:o Soma –cellbodycontainingthenucleusandorganelles, whereessentialmetabolic processes occur to maintain cell survivalo Axon andDendron– nervefibreswhichare strandsof cytoplasmextendingfromthe cell bodythattransmitnerveimpulsesto otherneurones or effectorso Dendrites- short-branchednervefibresthatconvertchemicalinformationfrom other neurons or receptor cells intoelectricalnerve impulses Concepts Summary NotesNan Hua High School Biology 2

Name: __________________ Topic: Nervous System Concepts Summary NotesNan Hua High School Biology 3

Name: __________________ Topic: Nervous System Types of neurones ● Sensoryneuronestransmitnerveimpulsesfromreceptorstotherelayneuronesinthespinal cord or brain. ● RelayneuronesintheCNS(spinalcord/brain)receivenerveimpulsesfromsensoryneuronesand transmit them along the CNS to themotorneurones. ● Motorneuronestransmitnerveimpulsesfrom the CNS to the effectors(muscles/glands)for an action to occur. ● Synapse–ajunctionorconnectionbetweentwoneurones(fromanaxonto a dendron)bychemicalmeansthroughneurotransmitters Concepts Summary NotesNan Hua High School Biology 4

Name: __________________ Topic: Nervous System LO:Discussthefunctionofthebrainandspinalcordinproducingaco-ordinatedresponse as a result of a specific stimulus in a reflex action ● Reflexactionisanimmediateinvoluntaryresponsetoaspecificstimuluswithoutconscious control.● Reflexarcistheshortestpathwaybywhichnerveimpulsesaretransmittedfromthereceptortotheeffector. Thenerveimpulsesgeneratedbythereceptoraretransmitted along thereflex arc.● Spinal cord and brain are known as thereflex centres. Concepts Summary NotesNan Hua High School Biology 5

Name: __________________ Topic: Nervous System Example of brain / cranial reflexes – pupil reflex ● Changein lightintensitystimulatesphotoreceptorsontheretinato generatenerve impulses.● Nerveimpulseswillbetransmittedalongthesensoryneuroneintheopticnerveacrossa synapsetotherelayneuroneinthebrainandacrossanothersynapseto themotor neuroneand to theeffector which isthemuscles of the iris.● Thecircularandradialmusclesoftheiriscontractandrelax(orviceversa)tobring about theconstriction and dilationof thepupil. Example of spinal reflex - Knee Jerk(no relay neurone involved): ● Tapstimulatesthetendonunderthe kneecap.● Nerve impulses are generatedand transmitted along thesensory neuroneto thespinalcordandacross a synapseto themotor neuroneand to theeffector (no relay neuroneinvolved). Concepts Summary NotesNan Hua High School Biology 6

Name: __________________ Topic: Nervous System ● Theeffectoris thethigh muscles which contracts, bringing abouta suddenkicking of the legs. Example of spinal reflex - touching a hot object ● Heat on the objectstimulatesthethermoreceptorsin the skin.● Nerve impulses are generated and transmittedalong the sensory neuroneto thespinal cord.● Nerve impulses are transmittedacross asynapseto therelay neuronein thespinal cordand thenacross another synapseto themotorneurone.● Nerve impulses are transmitted along themotorneuroneto theeffectorwhich is thearm musclewhichcontracts, bringing about asuddenwithdrawal of the hand.● At the same time,a relay neurone from thespinal cordwill also transmit nerve impulses tothebrainto bring about thepain sensation. Example of voluntary action – picking up a hot pan voluntarily ● Nerve impulses areinitiated and generated at thebrain.● Transmitted via therelay neuroneto thespinal cord● Acrossa synapseto themotorneuroneandto theeffectorwhichis thearmmuscles.● Arm muscles contractandhand is withdrawn. Concepts Summary NotesNan Hua High School Biology 7

Name: __________________ Topic: Nervous System Comparereflex actionandvoluntary action: Concepts Summary NotesNan Hua High School Biology 8