The Nervous SystemSlide 2The Nervous SystemSlide 4Subdivisions of Nervous SystemStructural ClassificationSlide 7Nervous TissueSupporting CellsSupport Cells: Glial CellsOligodendrocyteSlide 13About Neurons…Classification of NeuronsSlide 16Slide 17Neuron AnatomySlide 19Slide 20Slide 21ChannelsSENDING INFORMATION: NERVE IMPULSESending information (Cont.)Action Potential = Nerve ImpulseSodium-Potassium Pump: (Remember Me?)Na-K Pump: How it WorksVoltage-Regulated ChannelsINSIDE-0UT!!!GO!!!Saltatory ConductionSlide 32Neuron Cell Body LocationIt All Starts at The Sensory ReceptorSlide 35NEUROTRANSMITTERSSome NTs Stimulate AP, Some Inhibit APAfferent Neuron – Moving away from a central organ or point Relays messages from receptors to the CNSEfferent Neuron :Relays messages from the CNS to the motor neurons and organsSlide 40Slide 41Slide 42Neuron ClassificationSlide 44Slide 45Slide 46Simple Reflex ArcSlide 48Central Nervous System (CNS)Regions of the BrainCorpus CollasumCerebral Hemispheres (Cerebrum)Slide 53Sensory and Motor Areas of the Cerebral CortexSpecialized Areas of the CerebrumSlide 56Slide 57Slide 58Lobes of the CerebrumHypothalamusSlide 61Slide 62MidbrainEpithalamusSlide 65Reticular FormationThalamusBrain StemSlide 69Medulla OblongataPonsSlide 72The Nervous SystemCopyright © 2006 Pearson Education, Inc., publishing as Benjamin CummingsFigure 7.1Functional Classification of the Peripheral Nervous System Sensory (afferent) division Nerve fibers that carry information to the central nervous systemThe Nervous System•Responsible for linking the body to the external environment while maintaining complex processes•Neurons•With the aid of endocrine system, maintains homeostasis.• Epilepsy, Alzheimer’s Disease, MS, and Stroke are disorders of the nervous system.Subdivisions of Nervous SystemTwo major anatomical subdivisions•Central nervous system (CNS)–brain and spinal cord enclosed in bony coverings•Peripheral nervous system (PNS)– Every Nerve outside of the CNS!–NERVE: a bundle of neurons–GANGLIAN: a cluster of neuron bodies ( resembles a knot)Structural ClassificationCentral Nervous System (CNS) - •Consists of brain and spinal cord.• Occupies the dorsal body cavity•Interprets sensory informationPeripheral Nervous system (PNS) •Spinal Nerves- carry impulses to and from the spinal cord •Cranial Nerves- carry impulses to and from the brainSubdivisions of Nervous SystemNervous Tissue•The nervous system consists of nervous tissue…the unit cells being neurons and their supporting cells:•Supporting cellsSupporting CellsSupport Cells: Glial Cells10X as many neuroglial cells as neurons!!Collectively referred to as neuroglia.1. Oligodendrocytes (CNS)- Primary role is to produce myelin which encases the axons of neurons at points. Schwann cells do this in (PNS). 2. Astrocytes- a source of nourishment for neuronsa source of nourishment for neurons as they connect to capillaries. Also, regulates extra-cellular cellular space at synapse.3. Ependymal cells- provides the lining of the fluid-filled brain ventricular system. (epithelial cells)4. Microglia- phagocytes that remove cell debris or degenerating neurons or glia.Oligodendrocyte•Myelin: composed from lipids (contains cholesterol)•Creates nodes of ranvier•This insulation causes saltatory conduction, a more rapid conduction than w/out insulation•MS is a disease where myelated sheath is distorted (Multiple Sclerosis)Copyright © 2006 Pearson Education, Inc., publishing as Benjamin CummingsFunctional Classification of Neurons Interneurons (association neurons) Found in neural pathways in the central nervous system Connect sensory and motor neuronsAbout Neurons…•Neurons do NOT regenerate…( a few exceptions)•They lack centrioles: organelles which for spindles for mitosis.•Neurons of the hippocampus regenerate.Classification of Neurons•Extensions outside the cell body–Dendrites – conduct impulses toward the cell body–Axons – conduct impulses away from the cell bodyFigure 7.4aNeuron Anatomy•Cell body–Nissl substance – specialized rough endoplasmic reticulum–Neurofibrils – intermediate cytoskeleton that maintains cell shapeFigure 7.4aCopyright © 2006 Pearson Education, Inc., publishing as Benjamin CummingsHow Neurons Communicate at SynapsesFigure 7.10ChannelsSENDING INFORMATION: NERVE IMPULSESending Information- The nerve impulse refers to the series of separateaction potentials that take place segment bysegment as they move down the length of theaxon.All-or-None law – If an action potential starts at the beginning of theAxon, the action potential will continue at the samespeed segment to segment to the very end of theaxon.Sending information (Cont.)Definition of AP:action potential is a tiny electrical current that isgenerated when the positive sodium ions rushinside the axonWhat does This DO? the enormous increase of Na ions inside the axoncauses the inside to reverse its charge the inside becomes positive & the outsidebecomes negativeAction Potential = Nerve Impulse•Is an “all or nothing” response•Does not die out•Continues to end of axon•Series of depolarizations •Refractory period followsCopyright © 2006 Pearson Education, Inc., publishing as Benjamin CummingsStarting a Nerve Impulse Depolarization – a stimulus depolarizes the neuron’s membrane A deploarized membrane allows sodium (Na+) to flow inside the membrane The exchange of ions initiates an action potential in the neuronFigure 7.9a–cSodium-Potassium Pump: (Remember Me?)Na-K Pump: How it Works•A type of active transport. •3 sodium ions move out of cell•2 potassium ions move into cell.•ATP is needed as each of these ions are moving against their conc. gradient.•Mostly used in cardiac muscle and nervous tissue. Maintains Na+K gradient concentration.•MAINTAINS RESTING POTENTIAL!!! •Huge amount of ATP goes into this NaK pumps!Voltage-Regulated Channels•Characteristic of areas of excitable membrane•Capable of generating an action potential•Open or close in response to changes in transmembrane potential•Example: the sodium channel ( seen to the right)•At membrane potential of –60mV the channal opens, +30, it closesINSIDE-0UT!!!GO!!!Saltatory ConductionCopyright © 2006 Pearson Education, Inc., publishing as Benjamin CummingsThe Action Potential If the action potential (nerve impulse) starts, it is propagated over the entire