15 Figure 12-1 A Functional Overview of the Nervous System. Organization of the Nervous SystemCentral Nervous System (CNS) (brain and spinal cord)Integrate, process, and coordinate sensory data and motor commandsSensory informationwithinafferent divisionMotor commandswithinefferent divisionPeripheral Nervous System (PNS) (neural tissue outside the CNS)includesSomatic nervous system (SNS)Autonomicnervous system (ANS)Parasympathetic divisionSympathetic divisionReceptorsEffectorsSmooth muscleCardiac muscleGlandsAdipose tissueSpecial sensory receptorsVisceral sensory receptorsSomatic sensory receptorsmonitor smell, taste, vision, balance, and hearingmonitor internal organsmonitor skeletal muscles, joints, and skin surfaceSkeletal muscleSkeletal muscle
24 Figure 12-2a The Anatomy of a Multipolar Neuron. DendritesPerikaryonCell bodyTelodendriaNucleusAxonThis color-coded figure shows the four general regions of a neuron.a
25 Figure 12-2b The Anatomy of a Multipolar Neuron. Nissl bodies (RER and free ribosomes)Dendritic branchesMitochondrionAxon hillockInitial segment of axonAxolemmaAxonTelodendriaDirection of action potentialGolgi apparatusAxon terminalsNeurofilamentNucleolusNucleusDendriteSee Figure 12–3Presynaptic cellbAn understanding of neuron function requires knowing its structural components.Postsynaptic cell
36 Figure 12-4 Structural Classifications of Neurons. Anaxonic neuronBipolar neuronUnipolar neuronMultipolar neuronDendritesDendritesInitial segmentCell bodyDendritic branchesAxonDendriteCell bodyCell bodyAxonAxonCell bodyAxonAxon terminalsAxon terminalsAxon terminalsaAnaxonic neurons have more than two processes, and they are all dendrites.bBipolar neurons have two processes separated by thecell body.cUnipolar neurons have a single elongated process, with the cell body located off to the side.Multipolar neurons have more than two processes; there is a single axon and multiple dendrites.d
37 Figure 12-4a Structural Classifications of Neurons. Anaxonic neuronCell bodyaAnaxonic neurons have more than two processes, and they are all dendrites.
38 Figure 12-4b Structural Classifications of Neurons. Bipolar neuronDendritic branchesDendriteCell bodyAxonAxon terminalsbBipolar neurons have two processes separated by the cell body.
39 Figure 12-4c Structural Classifications of Neurons. Unipolar neuronDendritesInitial segmentAxonCell bodyAxonAxon terminalsUnipolar neurons have a single elongated process, with the cell body located off to the side.c
40 Figure 12-4d Structural Classifications of Neurons. Multipolar neuronDendritesCell bodyAxonAxon terminalsdMultipolar neurons have more than two processes; there is a single axon and multiple dendrites.