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Unit 7 nervous & special senses

The document describes the structure and function of the nervous system. It discusses the central nervous system (CNS), which includes the brain and spinal cord, and the peripheral nervous system (PNS), which includes nerves that connect the CNS to the rest of the body. It describes the functions of neurons and neuroglial cells that make up nervous tissue and help transmit signals. Specifically, it discusses the roles of astrocytes, oligodendrocytes, microglia, and Schwann cells. It also explains the functions of the somatic, autonomic, and enteric nervous systems and how they regulate voluntary and involuntary bodily processes.

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The NERVOUS SystemThe NERVOUS System
7.01 The three broad functions of7.01 The three broad functions of the nervous system:the nervous system: SensorySensory – senses stimuli from both within the bodysenses stimuli from both within the body and from the external environmentand from the external environment IntegrativeIntegrative – analyzes, interprets, and stores informationanalyzes, interprets, and stores information about the stimuli it has receives from theabout the stimuli it has receives from the sensory portion of the nervous systemsensory portion of the nervous system MotorMotor – responds to stimuli by some type of actionresponds to stimuli by some type of action muscular contractionmuscular contraction glandular secretionglandular secretion
7.02 Describe the general organization of7.02 Describe the general organization of the nervous system.the nervous system. Central Nervous System (CNS)Central Nervous System (CNS) – BrainBrain – Spinal CordSpinal Cord Peripheral Nervous System (PNS)Peripheral Nervous System (PNS) – Spinal Nerves (31 pairs)Spinal Nerves (31 pairs) – Cranial Nerves (I-XII pairs)Cranial Nerves (I-XII pairs) – SubdivisionsSubdivisions Autonomic Nervous System (ANS) - InvolutaryAutonomic Nervous System (ANS) - Involutary – SympatheticSympathetic – ParasympatheticParasympathetic Somatic Nervous System - VoluntarySomatic Nervous System - Voluntary
7.02 The Central Nervous System7.02 The Central Nervous System (CNS)(CNS) Brain and Spinal CordBrain and Spinal Cord CNS FunctionCNS Function – Sorts incoming sensorySorts incoming sensory informationinformation – Generates thoughts andGenerates thoughts and emotionsemotions – Forms and stores memoriesForms and stores memories – Stimulates muscle contractionsStimulates muscle contractions – Stimulates glandular secretionsStimulates glandular secretions
7.02 Peripheral Nervous System7.02 Peripheral Nervous System (PNS)(PNS) Spinal and Cranial NervesSpinal and Cranial Nerves – Spinal Nerves (31 pairs)Spinal Nerves (31 pairs) – Cranial Nerves (I-XII pairs)Cranial Nerves (I-XII pairs) – SubdivisionsSubdivisions Autonomic Nervous System (ANS) - InvolutaryAutonomic Nervous System (ANS) - Involutary – SympatheticSympathetic – ParasympatheticParasympathetic Somatic Nervous System - VoluntarySomatic Nervous System - Voluntary CNSCNS PNSPNS
GreenGreen is the PNSis the PNS CNSCNS
7.02 The Autonomic7.02 The Autonomic Nervous System (ANS)Nervous System (ANS) Contains sensory neurons mainly from theContains sensory neurons mainly from the viscera that convey information to theviscera that convey information to the CNSCNS Contains the efferent neurons that conductContains the efferent neurons that conduct impulses to smooth muscle, cardiacimpulses to smooth muscle, cardiac muscle, and glandsmuscle, and glands Unconscious controlUnconscious control Two divisions of the ANSTwo divisions of the ANS – Sympathetic Division - stimulatory effectSympathetic Division - stimulatory effect – Parasympathetic Division - inhibitory effectParasympathetic Division - inhibitory effect
SympatheticSympathetic Stimulatory.Stimulatory. “Fight or Flight”“Fight or Flight” ParasympatheticParasympathetic Inhibitory.Inhibitory.
7.02 The Somatic Nervous System7.02 The Somatic Nervous System (SNS)(SNS) Made up of sensory neurons thatMade up of sensory neurons that convey information from the cutaneousconvey information from the cutaneous and special sense receptors in the head,and special sense receptors in the head, body wall, and extremities to the CNSbody wall, and extremities to the CNS Also contains the motor neurons fromAlso contains the motor neurons from the CNS that conduct impulses to thethe CNS that conduct impulses to the skeletal musclesskeletal muscles
7.03 List the functions and7.03 List the functions and structures of neurons.structures of neurons. The nerve cells responsible for theThe nerve cells responsible for the special functions of the nervous systemspecial functions of the nervous system – sensingsensing - remembering- remembering - thinking- thinking – controlling muscle activitycontrolling muscle activity – controlling glandular secretionscontrolling glandular secretions Synapse - the functional relay pointsSynapse - the functional relay points between two neurons or between abetween two neurons or between a neuron and an effector organneuron and an effector organ – Neuromuscular JunctionNeuromuscular Junction – Neuroglandular JunctionNeuroglandular Junction
7.03 List the functions and7.03 List the functions and structures of neurons.structures of neurons. Cell Body (Soma or Perikaryon)Cell Body (Soma or Perikaryon) – nucleus, cytoplasm, organelles of a neuronnucleus, cytoplasm, organelles of a neuron Dendrites - tapered, highly branchedDendrites - tapered, highly branched processes protruding from the cell bodyprocesses protruding from the cell body – usually very shortusually very short – AFFERENT FUNCTIONAFFERENT FUNCTION Axons - long, thin, cylindrical processAxons - long, thin, cylindrical process – usually myelinatedusually myelinated – EFFERENT FUNCTIONEFFERENT FUNCTION
NeuronNeuron
NeuronsNeurons
7.03 List the functions and7.03 List the functions and structures ofstructures of neuroglialneuroglial cells:cells: Nervous system cells that support,Nervous system cells that support, nurture and protect the neuronsnurture and protect the neurons Types of Neuroglia found in theTypes of Neuroglia found in the CNSCNS – AstrocytesAstrocytes – OligodendrocytesOligodendrocytes – MicrogliaMicroglia – Ependymal CellsEpendymal Cells Types of Neuroglia found in theTypes of Neuroglia found in the PNSPNS – Neurolemmocytes (Schwann Cells)Neurolemmocytes (Schwann Cells) – Satellite CellsSatellite Cells
7.03 Astrocytes (Astroglia)7.03 Astrocytes (Astroglia) Star-shaped cells with many processesStar-shaped cells with many processes Forms the Blood Brain Barrier (BBB)Forms the Blood Brain Barrier (BBB) Forms the pia mater covering the brainForms the pia mater covering the brain and spinal cord.and spinal cord. Soaks up excess ions and toxinsSoaks up excess ions and toxins Participate in brain developmentParticipate in brain development Facilitates repair for CNS traumaFacilitates repair for CNS trauma
7.03 Astrocyte7.03 Astrocyte
7.03 Microglia7.03 Microglia Small phagocytic cells that protect theSmall phagocytic cells that protect the central nervous system by engulfingcentral nervous system by engulfing and invading microbesand invading microbes Clears awayClears away debris fromdebris from dead cellsdead cells
7.03 Oligodendrocytes7.03 Oligodendrocytes (Oligodendroglia)(Oligodendroglia) Oligo- small or fewOligo- small or few Small glial cells with few processesSmall glial cells with few processes Form a supporting network around theForm a supporting network around the neurons by twining around neuronsneurons by twining around neurons and producing a lipid and proteinand producing a lipid and protein wrapping around the neuronswrapping around the neurons ((myelin sheathmyelin sheath))
6.03 Oligodendrocyte6.03 Oligodendrocyte
7.03 Ependymal Cells7.03 Ependymal Cells Neuroglia cells lineNeuroglia cells line the brain ventriclesthe brain ventricles and the central canaland the central canal of the spinal cordof the spinal cord Form and circulateForm and circulate cerebral spinal fluidcerebral spinal fluid (CSF)(CSF)
7.03 Neuroglia of the PNS7.03 Neuroglia of the PNS (Schwann and Satellite cells)(Schwann and Satellite cells) Schwann CellsSchwann Cells - Neurolemmocytes- Neurolemmocytes – Cells responsible for producing the myelinCells responsible for producing the myelin sheaths around the PNS neuronssheaths around the PNS neurons Satellite CellsSatellite Cells – Similar to astrocytesSimilar to astrocytes – Structural supportStructural support – soaks up excess ionssoaks up excess ions and toxinsand toxins
7.03 Schwann Cell Myelination7.03 Schwann Cell Myelination
7.03 Myelination7.03 Myelination
7.03 Myelination7.03 Myelination The process of developing or producingThe process of developing or producing a Myelin Sheatha Myelin Sheath Insulates the axon of a neuronInsulates the axon of a neuron Increases the speed of nerve impulseIncreases the speed of nerve impulse conductionconduction – CNS - oligodendrocytesCNS - oligodendrocytes – PNS - neurolemmocytes (Schwann Cells)PNS - neurolemmocytes (Schwann Cells) Guillain-Barre syndrome and MultipleGuillain-Barre syndrome and Multiple Sclerosis are involved the destruction ofSclerosis are involved the destruction of the myelin sheaths around the nervethe myelin sheaths around the nerve
7.04 Contrast white and gray7.04 Contrast white and gray matter of nervous tissue.matter of nervous tissue. White MatterWhite Matter - the aggregation of- the aggregation of myelinatedmyelinated processes from manyprocesses from many neuronsneurons – Visible upon freshly dissected brain orVisible upon freshly dissected brain or spinal tissuespinal tissue – White color is due to myelinationWhite color is due to myelination Gray MatterGray Matter -- unmyelinatedunmyelinated nerve cellnerve cell bodies, axons, dendrites, ganglia, andbodies, axons, dendrites, ganglia, and axon terminalsaxon terminals – Appears gray because of lack of myelinAppears gray because of lack of myelin
7.04 Gray and White Matter7.04 Gray and White Matter
7.05 Describe the location, and7.05 Describe the location, and function of CSF.function of CSF. (ventricles, subarachnoid space)(ventricles, subarachnoid space) Cavities within the brainCavities within the brain Lateral ventricles (2) - located within eachLateral ventricles (2) - located within each hemisphere in the cerebrumhemisphere in the cerebrum Third ventricle - a vertical slit between theThird ventricle - a vertical slit between the lateral ventricles and inferior to the rightlateral ventricles and inferior to the right and left halves of the thalamusand left halves of the thalamus Fourth ventricle - space between theFourth ventricle - space between the brainstem and the cerebellumbrainstem and the cerebellum
7.05 Describe the location, and7.05 Describe the location, and function of CSF.function of CSF. (Choroid Plexus)(Choroid Plexus) Network of capillaries in the walls of theNetwork of capillaries in the walls of the ventriclesventricles Covered with ependymal cells that form theCovered with ependymal cells that form the cerebrospinal fluidcerebrospinal fluid These ependymal cells are so close togetherThese ependymal cells are so close together they form the blood-brain barrier.they form the blood-brain barrier. – Selectively permeable barrierSelectively permeable barrier – Protects the brain and spinal cord fromProtects the brain and spinal cord from potentially harmful substances in the bloodpotentially harmful substances in the blood
7.05 Blood Supply to the Brain7.05 Blood Supply to the Brain One of the most metabolically activeOne of the most metabolically active organs in the bodyorgans in the body Makes up only 2-3% of body weight butMakes up only 2-3% of body weight but uses about 20% of available Ouses about 20% of available O22 at restat rest Well supplied with OWell supplied with O22 and nutrientsand nutrients Only nutritional source for brainOnly nutritional source for brain metabolic activity is glucosemetabolic activity is glucose Capillaries in the brain are much lessCapillaries in the brain are much less leaky than other capillaries in the bodyleaky than other capillaries in the body and form a blood brain barrierand form a blood brain barrier
7.05 Describe the function of CSF.7.05 Describe the function of CSF. Mechanical ProtectionMechanical Protection – Serves as a shock absorbing mediumServes as a shock absorbing medium – Buoys the brain so it literally floats withinBuoys the brain so it literally floats within the cranial cavitythe cranial cavity Chemical ProtectionChemical Protection – Provides an optimal chemical environmentProvides an optimal chemical environment for neural signalingfor neural signaling CirculationCirculation – Acts as a medium for exchange of nutrientsActs as a medium for exchange of nutrients and waste products between the blood andand waste products between the blood and nervous tissuenervous tissue
7.05 Ventricles of the Brain7.05 Ventricles of the Brain
7.057.05 FlowFlow ofof Cerebro-Cerebro- SpinalSpinal FluidFluid (CSF)(CSF)
7.057.05 FlowFlow ofof Cerebro-Cerebro- SpinalSpinal FluidFluid
HydrocephalusHydrocephalus Blocked Cerebral AqueductBlocked Cerebral Aqueduct
7.06 Identify the structures responsible for7.06 Identify the structures responsible for the maintenance and protection of thethe maintenance and protection of the central nervous system.central nervous system. Protected by the cranial bones and the cranial meningesProtected by the cranial bones and the cranial meninges – Dura MaterDura Mater - outer layer- outer layer – ArachnoidArachnoid - middle layer- middle layer – Pia MaterPia Mater - inner layer- inner layer Also protected byAlso protected by cerebrospinal fluid (CSF)cerebrospinal fluid (CSF) – fluid that nourishes and protects the brain and spinal cordfluid that nourishes and protects the brain and spinal cord – continuously circulates through the subarachnoid spacecontinuously circulates through the subarachnoid space around the brain and throughout the cavities within thearound the brain and throughout the cavities within the brainbrain
7.06 Meninges7.06 Meninges Connective tissue covering foundConnective tissue covering found around the brain and spinal cordaround the brain and spinal cord Three layered membraneThree layered membrane – Dura Mater - outer most layerDura Mater - outer most layer dense irregular connective tissuedense irregular connective tissue – Arachnoid - middle layerArachnoid - middle layer spider web arrangement of collagen fibersspider web arrangement of collagen fibers – Pia Mater - inner most meningesPia Mater - inner most meninges very delicate layer of thin tissuevery delicate layer of thin tissue
7.06 Meninges of the Brain7.06 Meninges of the Brain
7.067.06 MeningesMeninges of theof the Spinal CordSpinal Cord Dura MaterDura Mater ArachnoidArachnoid -Subarachnoid Space-Subarachnoid Space Pia MaterPia Mater
The BRAINThe BRAIN
7.07 Identify the four principle7.07 Identify the four principle parts of the brain.parts of the brain. cerebrum, cerebellum, brain stem,cerebrum, cerebellum, brain stem, diencephalondiencephalon One of the largest organs in the bodyOne of the largest organs in the body Controls all mental functionsControls all mental functions Component of the CNSComponent of the CNS Composed of over 100 billion neuronsComposed of over 100 billion neurons Comprises 2-3% of body weightComprises 2-3% of body weight Utilizes over 20% of body’s energyUtilizes over 20% of body’s energy
CEREBRUMCEREBRUM - occupies most of the- occupies most of the cranium and is divided into right and leftcranium and is divided into right and left halves called hemisphereshalves called hemispheres CEREBELLUMCEREBELLUM - the posterior-inferior- the posterior-inferior portion of the brainportion of the brain BRAIN STEMBRAIN STEM - consists of the medulla- consists of the medulla oblongata, thoblongata, thee pons, and the midbrainpons, and the midbrain – it is continuous with the spinal cordit is continuous with the spinal cord DIENCEPHALONDIENCEPHALON - located above the- located above the brainstem, composed primarily of the:brainstem, composed primarily of the: – ThalamusThalamus -- HypothalamusHypothalamus
The BrainThe Brain
7.08 Describe the functions of7.08 Describe the functions of the three structures of thethe three structures of the brain stem.brain stem. The most inferior portion of the brainThe most inferior portion of the brain Connects the brain to the spinal cordConnects the brain to the spinal cord Composed of Three AreasComposed of Three Areas – The Medulla OblongataThe Medulla Oblongata – The PonsThe Pons – The MidbrainThe Midbrain
7.08 The Medulla Oblongata7.08 The Medulla Oblongata Most inferior portion of the brain stemMost inferior portion of the brain stem Connects the brain stem to the spinalConnects the brain stem to the spinal cordcord Respiratory Center ***Respiratory Center *** – Adjusts rhythm and depth of breathingAdjusts rhythm and depth of breathing Cardiovascular Center ***Cardiovascular Center *** – Regulates heart rate and contraction forceRegulates heart rate and contraction force – Influences vasoconstriction andInfluences vasoconstriction and vasodilationvasodilation Also controls coughing, vomiting,Also controls coughing, vomiting, swallowing, and hiccuppingswallowing, and hiccupping
The Medulla OblongataThe Medulla Oblongata
The Medulla OblongataThe Medulla Oblongata
7.08 The Pons7.08 The Pons Lies superior to the medulla oblongataLies superior to the medulla oblongata Together with the respiratory center inTogether with the respiratory center in the medulla helps control respirationthe medulla helps control respiration
The PonsThe Pons
7.08 The Midbrain7.08 The Midbrain Superior to the ponsSuperior to the pons Connects the brain stem to theConnects the brain stem to the diencephalondiencephalon
The MidbrainThe Midbrain
Pons and MidbrainPons and Midbrain
7.09 Describe the structures and7.09 Describe the structures and functions of the diencephalon.functions of the diencephalon. Area of the brain containing the:Area of the brain containing the: – ThalamusThalamus – HypothalamusHypothalamus
7.09 The Thalamus7.09 The Thalamus Oval structure that makes up 80% of theOval structure that makes up 80% of the diencephalondiencephalon Comprised of a pair of oval massesComprised of a pair of oval masses (mostly gray matter)(mostly gray matter) PrinciplePrinciple relay stationrelay station between thebetween the various sections of the brainvarious sections of the brain
The ThalamusThe Thalamus
7.09 The Hypothalamus7.09 The Hypothalamus A small portion of the diencephalonA small portion of the diencephalon located below the thalamuslocated below the thalamus One of the main regulators ofOne of the main regulators of homeostasis in the bodyhomeostasis in the body Lacks a blood brain barrierLacks a blood brain barrier Partially protected by the sella turcicaPartially protected by the sella turcica of the sphenoid boneof the sphenoid bone
7.09 Functions of the7.09 Functions of the HypothalamusHypothalamus Coordinates Nervous System andCoordinates Nervous System and Endocrine System activities to maintainEndocrine System activities to maintain HomeostasisHomeostasis – Thirst, Hunger, SatietyThirst, Hunger, Satiety – Sleep Patterns and Waking StatesSleep Patterns and Waking States – Sex Drive, Maturation, Aggression, andSex Drive, Maturation, Aggression, and RageRage – influences movement of food through theinfluences movement of food through the Gastrointestinal TractGastrointestinal Tract – production and secretion of hormones Thatproduction and secretion of hormones That control other Endocrine Glandscontrol other Endocrine Glands
The HypothalamusThe Hypothalamus
HypothalamusHypothalamus
7.10 Describe the locations and functions7.10 Describe the locations and functions of theof the four lobesfour lobes of the cerebrum.of the cerebrum. Largest division of the brainLargest division of the brain Occupies most of the craniumOccupies most of the cranium Accounts for 85% of brain massAccounts for 85% of brain mass Divided into right and left hemispheresDivided into right and left hemispheres – Longitudinal FissureLongitudinal Fissure – Corpus CallosumCorpus Callosum Cerebral cortex - the outer surface areaCerebral cortex - the outer surface area of the cerebrumof the cerebrum – Composed mainly of gray matterComposed mainly of gray matter – Contains billions of neuronsContains billions of neurons
The CerebrumThe Cerebrum
7.10 Describe the locations and7.10 Describe the locations and functions of the four lobes of thefunctions of the four lobes of the cerebrum.cerebrum. Named after the bones that cover themNamed after the bones that cover them – Frontal LobeFrontal Lobe – Parietal LobeParietal Lobe – Temporal LobeTemporal Lobe – Occipital LobeOccipital Lobe
7.10 Frontal Lobe7.10 Frontal Lobe Motor AreasMotor Areas – Controls movement of voluntary skeletalControls movement of voluntary skeletal musclesmuscles Association AreasAssociation Areas – Carry on high level intellectual processingCarry on high level intellectual processing Problem SolvingProblem Solving - Reasoning- Reasoning - Planning- Planning ConcentrationConcentration - Memory- Memory - Behavior- Behavior EmotionsEmotions - Expressions- Expressions
7.10 Parietal Lobe7.10 Parietal Lobe Sensory AreasSensory Areas – Interprets sensations such as:Interprets sensations such as: – touch - pressure - pain on the surface of thetouch - pressure - pain on the surface of the skinskin Association AreasAssociation Areas – Understanding of speechUnderstanding of speech – Using words to express thoughts andUsing words to express thoughts and feelingsfeelings
7.10 Temporal Lobe7.10 Temporal Lobe Sensory AreasSensory Areas – Hearing and balanceHearing and balance Association AreasAssociation Areas – Interpret sensory experiencesInterpret sensory experiences – Memory of visual scenes - music - smellsMemory of visual scenes - music - smells and other complex sensory patternsand other complex sensory patterns
7.10 Occipital Lobe7.10 Occipital Lobe Sensory AreasSensory Areas – Visual processing and interpretationVisual processing and interpretation Association AreasAssociation Areas – Combines visual images with sensoryCombines visual images with sensory experienceexperience
7.11 Explain the major7.11 Explain the major functions of the cerebellum.functions of the cerebellum. Second largest portion of the brainSecond largest portion of the brain Occupies the inferior and posteriorOccupies the inferior and posterior aspects of the cranial cavityaspects of the cranial cavity Processes sensory informationProcesses sensory information – BalanceBalance - Coordination- Coordination – Maintains postural equilibriumMaintains postural equilibrium
The CerebellumThe Cerebellum
Cerebellum and BrainstemCerebellum and Brainstem
7.11 Cerebellar Test7.11 Cerebellar Test Finger to Finger TestFinger to Finger Test Finger to Nose TestFinger to Nose Test Holme’s Sign (overreaction)Holme’s Sign (overreaction) Romberg’s Test (Eyes Closed)Romberg’s Test (Eyes Closed)
7.12 Sequence the major events7.12 Sequence the major events when the nerve impulsewhen the nerve impulse (action potential) is initiated(action potential) is initiated and transmitted through a neuron.and transmitted through a neuron. The transmission of nerveThe transmission of nerve (electrical) impulses from(electrical) impulses from nervous tissue to othernervous tissue to other nervous tissue, organs,nervous tissue, organs, glands, and muscles.glands, and muscles.
7.12 Neuron Membrane Potential7.12 Neuron Membrane Potential
7.12 Neuron Action Potential7.12 Neuron Action Potential
7.12 Transmission of Nerve7.12 Transmission of Nerve ImpulsesImpulses An electrical event due to movement ofAn electrical event due to movement of ions across a membraneions across a membrane Also called an action potentialAlso called an action potential – Lasts about 1 msec (1/1000 of a second)Lasts about 1 msec (1/1000 of a second) – Dependent upon diameter of the axonDependent upon diameter of the axon A-(thick myelin/fast), B-(thin myelin/moderate),A-(thick myelin/fast), B-(thin myelin/moderate), C-(unmyelin/slow) fibersC-(unmyelin/slow) fibers larger diameter axons - 0.4 msec (1/2500 sec)larger diameter axons - 0.4 msec (1/2500 sec) – 2500 impulses per second2500 impulses per second smaller diameter axons - 4 msec (1/250 sec)smaller diameter axons - 4 msec (1/250 sec) – 250 impulses per second250 impulses per second
7.12 All or None Principle7.12 All or None Principle If depolarization reaches a threshold, anIf depolarization reaches a threshold, an action potential (impulse) is conductedaction potential (impulse) is conducted Each action potential (impulse) isEach action potential (impulse) is conducted at maximumconducted at maximum strength unless there arestrength unless there are toxic materials withintoxic materials within the cell or the membranethe cell or the membrane has been disruptedhas been disrupted
7.12 Neuron Impulse7.12 Neuron Impulse
7.12 Transmission of Nerve7.12 Transmission of Nerve Impulses at SynapsesImpulses at Synapses Most nervous conduction is fromMost nervous conduction is from neuron to neuron (interneurons - 90%)neuron to neuron (interneurons - 90%) Types of SynapsesTypes of Synapses – Axon to dendriteAxon to dendrite – Axon to somaAxon to soma – Axon to axonAxon to axon Two ways to transmit impulses across aTwo ways to transmit impulses across a synapsesynapse – Electrical SynapsesElectrical Synapses – Chemical SynapsesChemical Synapses
7.127.12 NeuronNeuron ActionAction PotentialPotential
7.12 Types of Impulse Conduction7.12 Types of Impulse Conduction Continuous ConductionContinuous Conduction - step by step- step by step depolarization of each sequential,depolarization of each sequential, adjacent area of of the nerve celladjacent area of of the nerve cell membranemembrane – typical of unmyelinated nerve fiberstypical of unmyelinated nerve fibers – type of action potential in muscle fiberstype of action potential in muscle fibers Saltatory ConductionSaltatory Conduction - the jumping of- the jumping of an action potential across specializedan action potential across specialized neurofibril nodes along the axonneurofibril nodes along the axon – Nodes of RanvierNodes of Ranvier
7.12 Nerve Conduction7.12 Nerve Conduction
7.13 Explain the role of each of7.13 Explain the role of each of the components of a reflex arc.the components of a reflex arc. ((reflexreflex,, reflex arc:reflex arc: receptorreceptor,, sensory neuronsensory neuron,, associationassociation [interneuron] neuron[interneuron] neuron,, motor neuronmotor neuron,, effectoreffector))
7.13 The Reflex Arc:7.13 The Reflex Arc: receptor, sensoryreceptor, sensory neuron, association [interneuron] neuron,neuron, association [interneuron] neuron, motor neuron, effectormotor neuron, effector A response by the body involving onlyA response by the body involving only the body segment being affected andthe body segment being affected and the spinal cordthe spinal cord – Brain does not have to be involvedBrain does not have to be involved Receptor - the distal end of a sensoryReceptor - the distal end of a sensory neuron (dendrite)neuron (dendrite) – Responds to a specific stimulusResponds to a specific stimulus a change in internal or external environmenta change in internal or external environment – Triggers a nerve impulseTriggers a nerve impulse
Sensory Neuron - the neuron located inSensory Neuron - the neuron located in the gray matter of the spinal cordthe gray matter of the spinal cord – conducts impulses from the receptor to theconducts impulses from the receptor to the spinal cordspinal cord Integrating Center - a region within theIntegrating Center - a region within the CNS (spinal cord or brain) thatCNS (spinal cord or brain) that interprets the information from theinterprets the information from the sensory neuron and initiates ansensory neuron and initiates an appropriate responseappropriate response Motor Neurons - the neurons arisingMotor Neurons - the neurons arising from the integrating center that relay afrom the integrating center that relay a nerve impulse to the part of the bodynerve impulse to the part of the body that will respond to the stimulusthat will respond to the stimulus
Effector - the part of the body thatEffector - the part of the body that responds to the motor nerve impulseresponds to the motor nerve impulse (usually a muscle or a gland)(usually a muscle or a gland) – Effector - skeletal muscle - somatic reflexEffector - skeletal muscle - somatic reflex – Effector - cardiac, smooth muscle, or glandEffector - cardiac, smooth muscle, or gland -visceral reflex-visceral reflex
7.13 The Peripheral7.13 The Peripheral Nervous System (PNS)Nervous System (PNS) Connects sensory receptors, muscles,Connects sensory receptors, muscles, and glands in the peripheral parts of theand glands in the peripheral parts of the body to the central nervous systembody to the central nervous system Consists of cranial and spinal nervesConsists of cranial and spinal nerves Afferent Neurons (Sensory)Afferent Neurons (Sensory) – conduct nerve impulses from sensoryconduct nerve impulses from sensory receptors toward the CNSreceptors toward the CNS Efferent Neurons (Motor)Efferent Neurons (Motor) – conduct nerve impulses fromconduct nerve impulses from the CNS to muscles and glandsthe CNS to muscles and glands CNSCNS PNSPNS
7.13 The Reflex Arc7.13 The Reflex Arc
7.13 Reflex arc (Reflexes).7.13 Reflex arc (Reflexes). Fast, predictable, automatic responsesFast, predictable, automatic responses to changes in the environment that helpto changes in the environment that help maintain homeostasismaintain homeostasis Somatic Reflexes - involve skeletalSomatic Reflexes - involve skeletal musclesmuscles Visceral (Autonomic) Reflexes - involveVisceral (Autonomic) Reflexes - involve responses of smooth muscles, the heart,responses of smooth muscles, the heart, and glandsand glands Involve the spinal nervesInvolve the spinal nerves
7.13 Reflex Arc Examples7.13 Reflex Arc Examples Stretch Reflex - results in theStretch Reflex - results in the contraction of a muscle if it has beencontraction of a muscle if it has been stretched suddenlystretched suddenly Tendon Reflex - results in theTendon Reflex - results in the contraction of a muscle when a tendoncontraction of a muscle when a tendon is stretched suddenlyis stretched suddenly Flexor (Withdrawal) Reflex - suddenFlexor (Withdrawal) Reflex - sudden contraction and removal of a bodycontraction and removal of a body segment as a result of a pain stimulussegment as a result of a pain stimulus
7.13 Tendon Reflex7.13 Tendon Reflex
7.137.13 WithdrawalWithdrawal ReflexReflex also calledalso called FlexorFlexor /Withdrawal/Withdrawal ReflexReflex
07.14 Identify the following07.14 Identify the following diseases or disorders of thediseases or disorders of the nervous system.nervous system. (ALS, Alzheimer’s, bacterial(ALS, Alzheimer’s, bacterial meningitis, cerebral palsy,meningitis, cerebral palsy, epilepsy, multipleepilepsy, multiple sclerosis, Parkinson’s,sclerosis, Parkinson’s, Guillain-Barre syndrome)Guillain-Barre syndrome)
7.14 Amyotrophic Lateral7.14 Amyotrophic Lateral Sclerosis (ALS)Sclerosis (ALS) Also known as Lou Gehrig’s DiseaseAlso known as Lou Gehrig’s Disease A relatively rare neurological disorderA relatively rare neurological disorder A syndrome marked by muscular weaknessA syndrome marked by muscular weakness and atrophy with spasticity and hyperflexionand atrophy with spasticity and hyperflexion due to degeneration of the motor neurons ofdue to degeneration of the motor neurons of the spinal cord, medulla, and cortexthe spinal cord, medulla, and cortex A degenerative diseaseA degenerative disease No known cureNo known cure
7.14 Alzheimer’s Disease (AD)7.14 Alzheimer’s Disease (AD) Disabling neurological disorder thatDisabling neurological disorder that effects about 11% of the populationeffects about 11% of the population Fourth leading cause of brain deathFourth leading cause of brain death among the elderlyamong the elderly A chronic, organic, mental disorder, aA chronic, organic, mental disorder, a form of pre-senile dementia due toform of pre-senile dementia due to atrophy of neurons of the frontal andatrophy of neurons of the frontal and occipital lobesoccipital lobes AD patients usually die fromAD patients usually die from complications due to being bedriddencomplications due to being bedridden
7.14 Bacterial Meningitis7.14 Bacterial Meningitis Infection of the meninges by theInfection of the meninges by the bacterium Haemophilus Influenzaebacterium Haemophilus Influenzae Usually affects children under age 5Usually affects children under age 5 Symptoms include severe headachesSymptoms include severe headaches and feverand fever Can lead to brain damage and evenCan lead to brain damage and even death if not treateddeath if not treated
Brudzinki’s SignBrudzinki’s Sign