Fundamentals of the Nervous System and Nervous TissueIntroductionNervous System FunctionsSlide 4Organization of the Nervous SystemOrganizationOrganizationSlide 8Innervation of Visceral OrgansSlide 10Peripheral Nervous SystemHistology of the Nervous TissueSupporting CellsSupporting Cells in the CNSAstrocytesSlide 16MicroglialSlide 18Slide 19EpendymalOligodendro- cytesSupporting Cells of the PNSSatellite CellsSchwann CellsNeuronsNeuron CharacteristicsSlide 27Neuron structureNeuron Cell BodySlide 30Slide 31Neuron Cell BodiesNeuron ProcessesSlide 34Slide 35DendritesSlide 37AxonsSlide 39Myelinated AxonSlide 41Myelinated ProcessesMyelination of an AxonSlide 44Myelinated AxonsSlide 46Slide 47CNS AxonsSlide 49Classification of NeuronsStructural ClassificationMultipolar NeuronsBipolar NeuronsUnipolar NeuronFunctional ClassificationSensory NeuronsSensory Neurons: BipolarSlide 58Motor NeuronsAssociation Neurons or InterneuronsTurn to Basic Concepts of Neural IntegrationNeural IntegrationNeuronal PoolsSlide 64Slide 65Slide 66Types of CircuitsDiverging CircuitsSlide 69Converging CircuitsSlide 71Reverberating (oscillating) CircuitsSlide 73Parallel After-Discharge CircuitsSlide 75Patterns of Neural ProcessingSerial ProcessingReflexesSerial Processing: A Reflex ArcParallel ProcessingSlide 81Slide 82Slide 83Chapter 11: Fundamentals of the Nervous System and Nervous TissueFundamentals of the Nervous System and Nervous TissueChapter 11IntroductionThe nervous system is the master controlling and communicating system of the bodyIt is responsible for all behaviorAlong with the endocrine system it is responsible for regulating and maintaining body homeostasisCells of the nervous system communicate by means of electrical signalsNervous System FunctionsThe nervous system has three overlapping functionsGathering of sensory inputIntegration or interpretation of sensory inputCausation of a response or motor outputIntroductionSensory inputThe nervous system has millions of sensory receptors to monitor both internal and external changeIntegrationIt processes and interprets the sensory input and makes decisions about what should be done at each momentMotor outputCauses a response by activating effector organs (muscles and glands)Organization of the Nervous SystemOrganization There is only one nervous system; however, for convenience the nervous system is divided into two partsThe central nervous system•Brain and spinal cord•Integrative and control centersThe peripheral nervous system•Spinal and cranial nerves•Communication lines between the CNS and the rest of the bodyOrganizationThe peripheral nervous system has two fundamental subdivisionsSensory (afferent) division•Somatic and visceral sensory nerve fibers•Consists of nerve fibers carrying impulses to the central nervous systemMotor (efferent) division•Motor nerve fibers•Conducts impulses from the CNS to effectors–(glands and muscles)OrganizationThe motor division of the peripheral nervous system has two main subdivisionsThe somatic nervous system•Voluntary (somatic motor)•Conducts impulses from the CNS to skeletal muscleThe autonomic nervous system (ANS)•Involuntary•Conducts impulses from the CNS to cardiac muscles, smooth muscles, and glandsInnervation of Visceral OrgansOrganizationThe autonomic nervous system has two principle subdivisionsSympathetic division•Mobilizes body systems during emergency situationsParasympathetic division•Conserves energy•Promotes non-emergency functionsThe two subdivisions bring about opposite effects on the same visceral organsWhat one subdivision stimulates, the other inhibitsPeripheral Nervous SystemVisceral organs are served by motor fibers of the autonomic nervous system and by visceral sensory fibersThe somata (limbs and body wall) are served by motor fibers of the somatic nervous system and by sensory somatic sensory fibersArrows indicate the direction of impulsesHistology of the Nervous TissueNervous tissue is highly cellular Less that 20% of the CNS is extracellular spaceCells are densely packed and tightly intertwinedNervous tissue is made up of two cell typesNeurons•Excitable cells that transmit electrical signalsSupport cells•Smaller cells that surround and wrap the delicate neuronsThese same cells are found within CNS and PNSSupporting CellsAll neurons associate closely with nonnervous support cells of which there are 6 typesSupport cells of the CNS•Astrocytes•Microglial•Ependymal•OligodendrocyteSupport cells of the PNS•Schwann cells•Satellite cellsSupporting Cells in the CNSThe supporting cells of the CNS are collectively called neuroglia or simply, glial cellsLike neurons, glial cells have branching processes and a central cell bodyNeuroglia can be distinguished by their much smaller size and by their darker staining nucleiThey outnumber neurons in the CNS by a ration of 10 to 1Make up half of the mass of the brainAstrocytesStar shapedMost abundant type of glial cellRadiating projections cling to neurons and capillaries, bracing the neurons to their blood supplyAstrocytes play a role in exchanges between capillaries and neuronsAstrocytesCells function as antigen presenting cells of the immune response Control chemical environment around neurons, recapturing potassium ions and released neuro- transmittersAstrocytes signal each other via intracellular calcium pulsesMicroglialSmall ovid cells with relatively long “thorny” processes Their branches touch nearby neurons to monitor health of the neuronMicroglial migrate toward injured neuronsMicroglialSmall ovid cells with relatively long “thorny” processes Their branches touch nearby neurons to monitor health of the neuronMicroglial migrate toward injured neuronsMicroglialWhen invading micro- organisms are present or damaged neurons have died, the micro- glial transforms into a special type of macro- phage that protects the CNS by phagocytizing the microorganisms or neuronal debrisImportant because cells of the immune system can enter CNSEpendymalRange in shape from squamous to columnar and many are cilatedLine the central cavities of the brain and spinal cordForm a fairly permeable barrier between cerebrospinal fluid of those cavities and the cells of the CNSBeating cilia circulates cerebrospinal fluidOligodendro-