THE NERVOUS SYSTEM

http://www.youtube.com/watch?v=YRwPMICvbT4

I. IntroductionA.Functions of N.S.

1.Sensory input 2.Integration 3.Homeostasis 4.Mental activity 5.Control of

skeletal muscles

I. I. IntroductionIntroductionB. Divisions of the N.S.

Central N.S.Central N.S. Peripheral Peripheral N.S.N.S.

BraiBrainn

Spinal Spinal CordCord

AutonomiAutonomicc

SomatiSomaticcParasympathParasympath

eticeticSympathetSympatheticic

EfferentEfferent AfferenAfferentt

I. I. IntroductionIntroductionB. Divisions of the N.S.

Central N.S.Central N.S. Peripheral Peripheral N.S.N.S.

BraiBrainn

Spinal Spinal CordCord

No potential No potential for for regenerationregeneration

Made of 12 Made of 12 cranial nerves & cranial nerves & 31 spinal nerves31 spinal nerves

PNSA.Afferent (sensory)

division carries messages toward CNS.

B.Efferent (motor) division carries messages away from CNS toward muscles & glands (somatic).

Sympathetic NSSympathetic NSFight or Flight• Dilates pupils• Reduces saliva,

mucus, peristalsis, intestinal motility, urine secretion

• Increases heart rate, glycogen to glucose conversion

Parasympathetic Parasympathetic NSNSDigest & Rest

• Constricts pupils• Reduces heart

rate• Increases mucus

production, gastric juice production, digestion, urine production, intestinal tract motility, peristalsis

II. Histology of the N.S.II. Histology of the N.S.

A.Neurons – 1. Are excitable, irritable, & conductive.

– nerve cells– functional unit of n.s.

Neurons are not nerves!Neurons are not nerves!Nerves are bundles of PNS fibers held together by Nerves are bundles of PNS fibers held together by

several layers of connective tissueseveral layers of connective tissue

2 types of cells: neurons & support cells (neuroglia)

A. Neurons 2. Structure.Structure.

 a. Cell bodyCell body b. DendritesDendritesreceive incoming signals towards cell body

A. Neurons 2. StructureStructure

 c. AxonsAxons

transmit signals away from cell body

c. c. AxonsAxons• Myelin SheathMyelin Sheath -

membrane "insulation" around axons

• Nodes of Nodes of RanvierRanvier - gaps between myelin

2. Structure

c. c. AxonsAxons• Nissil bodiesNissil bodies -

rough endoplasmic reticulum... Lots of protein synthesis

• Synaptic vesiclesSynaptic vesicles - stores neurotransmitter at axon terminal

2. Structure

Structural Classification of Neurons

A. Neurons do not reproduce themselves, but they can regenerate new parts sometimes.

B. If a neuron is cut through a myelinated axon, the proximal portion may survive if the cell body is not damaged.

C. The distal portion will die (degenerate). Macrophages move into the area and remove debris.

D. Neuron cell body reorganizes its Nissl bodies to provide proteins necessary for axon growth.

E. The Schwann cells form a regeneration tube that helps guide the axon to its proper destination.

Regeneration

F. New fiber will eventually fill the myelin sheath and innervate the muscle. Growth occurs at 3-5 mm/day. (1 mm = 0.04 inch)

G. In the CNS, this repair is unlikely because the neurons lack the neurilemma necessary to form the regeneration tube. Also, the astrocytes quickly fill the damaged area forming scar tissue. Most CNS injuries cause permanent damage.

Regeneration

H. Crushing and bruising can also damage nerve fibers resulting in paralysis. Inflammation of the injury site damages more fibers. Early treatment with methyprednisolone reduces inflammation and decreases severity of injury. It must be given within 8 hours to be effective.

http://www.youtube.com/watch?v=kxVMog4PkYo

Regeneration

II. Histology of the N.S.B.B.Neuroglia – Neuroglia – nonexcitablenonexcitable;;

help & support neuronsOF THE CNSOF THE CNS1.1.Astrocytes Astrocytes - "nurse" cells;

nourish & protect neurons; form blood brain barrier

2.2.Oligodendrocytes Oligodendrocytes - form myelin in CNS

II. Histology of the N.SII. Histology of the N.S..B.B.Neuroglia – Neuroglia – nonexcitablenonexcitable;;

help & support neuronsOF THE CNSOF THE CNS 3.3.Microglia Microglia - provide

immune protection in CNS.

4.4.Ependymal cells Ependymal cells –circulate cerebrospinal fluid

II. Histology of the N.S.B.Neuroglia – OF THE OF THE

PNSPNS5.5.Schwann CellsSchwann Cells - form

myelin in peripheral nerves

6.6.Satellite CellsSatellite Cells – surround and support neurons of the ganglia

C. Nerves and Ganglia1.1.NervesNerves

a.bundles of nerve cell axons and/or dendrites in periphery of body.

b.Functional classification• Sensory (afferent) Sensory (afferent)

nervesnerves carry incoming signals from sense receptors towards CNS.

C. Nerves and Ganglia1.1.NervesNerves

b. Functional classification• Motor (efferent) nerves Motor (efferent) nerves –

carry outgoing (away from CNS) signals to muscle & glands.

• Interneurons nervesInterneurons nerves – connect motor and sensory neurons

C. Nerves and Ganglia2.2.Ganglia.Ganglia.

Ganglia are bundles of nerve cell bodies in periphery of body.

II. Histology of the N.S.D.Gray & White Matter

1.1.White MatterWhite Matter• Made of mylinated

processes2.2.Gray MatterGray Matter

• Unmylinated processes and cell bodies

II. Histology of the N.S.D.Gray & White Matter

3. Location3. Location Spinal cord gray matter forms H in center surrounded by white matter

II. Histology of the N.S.D.Gray & White Matter

3. Location3. LocationBrain central white matter with a superficial gray matter covering

III. Neurophysiology A.Membrane Properties1. Neurons must be able to transmit their

excitable response that started either in the dendrites or the nerve cell body down through the axon.

2. When at rest, the neuron has more + charges outside the cell membrane than inside.

3. This electric imbalance called the restingresting membrane potentialmembrane potential or simply stated the Resting potential is the difference b/w the 2 sides of the neuron’s membrane when the cell is not conducting an impulse

Resting PotentialResting Potential

A. Membrane Properties3. Resting Potential ion 3. Resting Potential ion

distribution distribution • Lg # NaLg # Na++ outside; K outside; K++ inside inside

A. Membrane Properties4.4. Changes in ion distribution Changes in ion distribution

causecauseStimulation of membrane Opens ion channels (pores) ion channels (pores)•When this occurs it is called an When this occurs it is called an Action Potential or simply stated Action Potential or simply stated an an Action potential is the electrical signal that rapidly travels along the axon of neurons causing changes in ion distribution.

III. Neurophysiology B.Action Potentials

1.Are a specialized kind of electric signal generated only by neurons and muscle cells

2.are self-propagating 3.are all-or-none events.

III. Neurophysiology C.Action Potentials have 3

Phases1.1.Depolarization Depolarization

• Rapid (1 msec)Rapid (1 msec)• sodium channels open, sodium channels open,

NaNa++ rush in rush in

III. Neurophysiology C.Action Potentials have 3

Phases1.1.Depolarization Depolarization •Ends in an Ends in an overshoot overshoot

(i.e. brief period of (i.e. brief period of time time inside of cell is inside of cell is more more positive than positive than outside)outside)

III. Neurophysiology C.Action Potentials have 3

Phases2.2.Repolarization Repolarization

• Na+ channels close Na+ channels close • K+ channels open and K+ channels open and

K+ rushes out K+ rushes out

III. Neurophysiology C.Action Potentials have 3

Phases2.2.Repolarization Repolarization • overshoots the overshoots the

resting pointresting point

III. Neurophysiology C.Action Potentials have 3

Phases3.3.Undershoot Phase Undershoot Phase

• Membrane is Membrane is hyperpolarized back to the hyperpolarized back to the resting potential resting potential

• KK++ channels close channels close• NaNa++/K/K++ pump reestablishes pump reestablishes

the resting potentialthe resting potential• 3 Na3 Na+ + movedmoved for 2 Kfor 2 K++

NaNa++ / K / K++ Pump Pump Reestablishes Resting Reestablishes Resting

PotentialPotential

III. Neurophysiology D.Nerve Impulse

1.1. Impulse conduction Impulse conduction • Unmyelinated fibers Unmyelinated fibers

conduct impulse over entire conduct impulse over entire membrane surface.membrane surface.

• Myelinated fibers conduct Myelinated fibers conduct impulse from node to nodeimpulse from node to node

2.2.Action potential spreads Action potential spreads down the fiber to adjacent down the fiber to adjacent areas of membraneareas of membrane

http://www.youtube.com/watch?v=FR4S1BqdFG4How the neurons work with the brain

III. Neurophysiology E.All or None Response

1.1.If the nerve fiber responds If the nerve fiber responds to the impulse, it responds to the impulse, it responds completelycompletely

2.2.Greater intensity of Greater intensity of stimulation triggers more stimulation triggers more impulses per second, not impulses per second, not stronger impulsesstronger impulses

IV. The Synapse A.Defined

The junction (cleft) between 2 The junction (cleft) between 2 neuronsneurons

IV. The Synapse B.B.Synaptic TransmissionSynaptic Transmission

1.1.The process by which the The process by which the impulse is transmitted across impulse is transmitted across the synaptic cleft the synaptic cleft

IV. The Synapse B.B.Synaptic Synaptic

TransmissionTransmission2.2.StepsSteps

• Impulse reaches Impulse reaches the synaptic the synaptic knobs of axonknobs of axon

• synaptic synaptic vesicles release vesicles release neurotransmitteneurotransmitter into the cleftr into the cleft

IV. The Synapse C.C.Kinds of Kinds of

NeurotransmittersNeurotransmitters 1.1.Acetylcholine (ACh)Acetylcholine (ACh)

• Made from acetic acidMade from acetic acid2.2.Biogenic AminesBiogenic Amines

• Made from amino acidsMade from amino acids• Include: Include:

dopamine, dopamine, epinephrine (adrenaline), epinephrine (adrenaline), norepinephrine (noradrenaline), norepinephrine (noradrenaline),

Serotonin and histamineSerotonin and histamine

C. Kinds of Neurotransmitters 3.3.Amino AcidsAmino Acids

4.4.PeptidesPeptides (includes (includes endorphins)endorphins)

5.5.ATPATP6.6.Nitric Oxide (NO)Nitric Oxide (NO)7.7.Carbon monoxide (CO)Carbon monoxide (CO)

Nicotine mimics acetylcholine but can block function by producing sustained depolarization

V. The Reflex ArcA.A.The Pathway The Pathway

1.1.ReceptorsReceptors2.2.Sensory NeuronSensory Neuron3.3.CNS Integration CNS Integration

CenterCenter4.4.Motor NeuronMotor Neuron5.5.EffectorEffector

B.B.ReflexesReflexes1.1.Are rapid, Are rapid,

automatic automatic responses responses to to stimulistimuli

2.2.A A specific specific stimulus stimulus produceproduces the s the same same motor motor responseresponse

VI. The BrainA.A.The Cerebrum The Cerebrum

1.1. FunctionFunctiona.a.Thinking and Thinking and

consciousness consciousness b.b.Willed movements Willed movements c.c.MemoryMemoryd.d.VisionVisione.e.HearingHearingf.f. Sensory perceptionSensory perceptiong.g.EmotionsEmotionsh.h.SpeechSpeech

A. The CerebrumA. The Cerebrum2. General Comments2. General Comments

a.a.83% of total weight of brain 83% of total weight of brain b.b.Paired cerebral hemispheres Paired cerebral hemispheres

A. The CerebrumA. The Cerebrum3. Anatomy3. Anatomy

a.a.Lobes Lobes Named for bones Named for bones over themover them• FrontalFrontal• TemporalTemporal• ParietalParietal• OccipitalOccipital• InsulaInsula

(limbic) –inside lateral (limbic) –inside lateral sulcussulcus

Frontal Lobe - Responsible for the elaboration of thinking, planning, programming individual needs and emotion.

Parietal Lobe - Responsible for the sensation of pain, touch, taste, temperature, pressure. It is also related with mathematics and logics.

Temporal Lobe - It is primarily related with auditory sense, allowing the recognition of specific tones and sound intensity. This area has also a role in memory and emotion processing.

Occipital Lobe - Responsible for the processing of visual information. Damage to this area results in partial or complete blindness.

Limbic Lobe - It is involved in the emotional and sexual aspects of behavior and in the processing of memory.

A. The CerebrumA. The Cerebrum3. Anatomy3. Anatomy

b.b.FissuresFissuresDeep groovesDeep grooves• Longitudinal (median, between Longitudinal (median, between

cerebral hemispheres)cerebral hemispheres)• Transverse (between cerebrum Transverse (between cerebrum

and cerebellum)and cerebellum)c.Sulcic.Sulci (sulcus singular) (sulcus singular)

Shallow groovesShallow grooves• Central: between frontal/parietalCentral: between frontal/parietal• Parieto-occipitalParieto-occipital• Lateral: between Lateral: between

temporal/frontal/ temporal/frontal/ parietalparietal

A. The CerebrumA. The Cerebrum3. Anatomy3. Anatomy

b.b.Gyri (gyrus singular)Gyri (gyrus singular)Elevated ridges of tissue Elevated ridges of tissue • Precentral Precentral (anterior to central sulcus)(anterior to central sulcus)• Postcentral Postcentral (posterior to central (posterior to central

sulcus)sulcus)c.Basic Regionsc.Basic Regions

CortexCortex• Outer layerOuter layer• Gray MatterGray Matter

White MatterWhite Matter – internal – internalBasal NucleiBasal Nuclei

• Islands of gray matter inside white Islands of gray matter inside white mattermatter

Memorize parts of Brain Memorize parts of Brain SongSong

http://www.youtube.com/watch?v=vYwOtTMUz0c

VI. The BrainB.B.The Diencephalon The Diencephalon

1.1. Consists ofConsists ofa.a.ThalamusThalamusb.b.Hypothalamus Hypothalamus c.c.EpithalamusEpithalamus

VI. The BrainB.B.The Diencephalon The Diencephalon

2.2. ThalamusThalamusa.a.““Gateway of the Gateway of the

Cerebral Cortex”Cerebral Cortex”for afferent for afferent

(sensory) (sensory) fibers fibers especially touch & tasteespecially touch & taste

b.b.Relay station for Relay station for sensory and motor sensory and motor impulses impulses

VI. The BrainB.B.The Diencephalon The Diencephalon

3.3. HypothalamusHypothalamusa.a.Autonomic control centerAutonomic control centerb.b.Main visceral control Main visceral control

center of the bodycenter of the bodyc.c.Involved in regulation ofInvolved in regulation of

• Body temperatureBody temperature• Water balance and thirstWater balance and thirst• Food intake and Food intake and

metabolismmetabolism• Sleep and wake cyclesSleep and wake cycles

VI. The BrainB.B.The Diencephalon The Diencephalon

3.3. HypothalamusHypothalamusc.c.Involved in regulation ofInvolved in regulation ofd.d.Endocrine functionsEndocrine functions

• Regulates pituitaryRegulates pituitaryProduces releasing and Produces releasing and inhibiting hormonesinhibiting hormones

• Produces hormonesProduces hormones• Antidiuretic hormone Antidiuretic hormone

(ADH)(ADH)• OxytocinOxytocin

B.B.The Diencephalon The Diencephalon 3.3. HypothalamusHypothalamus

c.c.Involved in regulation ofInvolved in regulation ofd.d.Endocrine functionsEndocrine functionse.e.Center for emotional Center for emotional

response and behaviorresponse and behavior• Thirst centerThirst center• Appetite centerAppetite center• Sex (sexual arousal) Sex (sexual arousal)

centercenter• Pain center Pain center • Pleasure centerPleasure center• Fear & AngerFear & Anger

B.B.The Diencephalon The Diencephalon 4.4. EpithalamusEpithalamusa.a.Forms roof of Forms roof of

33rdrd ventricleventricle

b.b.Pineal Gland or Pineal Gland or BodyBody• Secretes Secretes

melatoninmelatonin• Regulates Regulates

sleep-wake sleep-wake cycles and cycles and moodsmoods

c.c.Choroid Choroid PlexusPlexus• Forms Forms

cerebral cerebral spinal spinal fluidfluid

VI. The BrainC.C.The Brain Stem The Brain Stem

1.1. MidbrainMidbrain2.2. PonsPons3.3. Medulla OblongataMedulla Oblongata

VI. The BrainC.C.The Brain Stem The Brain Stem

1.1. MidbrainMidbraina.a.Conduction Conduction

pathway pathway between between higher and higher and lower brain lower brain centerscenters

b.b.Cranial Cranial Nerves III & Nerves III & IVIV

Oculomotor & Trochlear (eye movement)

VI. The BrainC.C.The Brain Stem The Brain Stem

2.2. PonsPonsa.a.Conduction Conduction

pathway pathway between between higher and higher and lower brain lower brain centerscenters

b.b.Regulates Regulates breathingbreathing

c.c. Cranial Nerves V – VIICranial Nerves V – VIITrigeminal, Trigeminal, Abducens, Abducens, && Facial FacialFace sensory & chewingFace sensory & chewing; rolls eye ; rolls eye

laterally; laterally; & & facial expression & tastefacial expression & taste

C.C.The Brain Stem The Brain Stem 3.3. MedullaMedulla

a.a.Autonomic reflex center Autonomic reflex center for body homeostasisfor body homeostasis

b.b.CentersCenters• CardiacCardiac• VasomotorVasomotor• RespiratoryRespiratory• VomitingVomiting• HiccuppingHiccupping• SwallowingSwallowing• Coughing Coughing • SneezingSneezing

c.c. Cranial Nerves VIII – XIICranial Nerves VIII – XIIVestibulocochlear, Vestibulocochlear,

GlossopharyngealGlossopharyngeal,Vagus,,Vagus,AccessoryAccessory,&Hypoglossal,&HypoglossalHearing; Hearing; swallow & tasteswallow & taste; GI activity & Heart activity; GI activity & Heart activity; ; acts on acts on

sternocleidomastoid & trapezius muscles;sternocleidomastoid & trapezius muscles; & control tong & control tong movement & sensory impulsesmovement & sensory impulses

VI. The BrainD.D.Cerebellum Cerebellum

1.1.Assists in maintaining Assists in maintaining • BalanceBalance• PosturePosture• EquilibriumEquilibrium

2.2.Coordinates skeletal muscleCoordinates skeletal muscle

VI. The BrainE.E. Functional Brain SystemsFunctional Brain Systems

1.1. Limbic System Limbic System • Our emotional or affective (feelings) brainOur emotional or affective (feelings) brain• Includes hypothalamus and parts of the Includes hypothalamus and parts of the

cerebrumcerebrum

VI. The BrainE.E. Functional Brain SystemsFunctional Brain Systems

2.2. The Reticular Formation The Reticular Formation • Involved in arousal of the brainInvolved in arousal of the brain• Filters the flood of sensory input (99% filtered out)Filters the flood of sensory input (99% filtered out)

– Filters out repetitive, familiar or weak signalsFilters out repetitive, familiar or weak signals– Passes on unussual, strong, or significant signalsPasses on unussual, strong, or significant signals

VI. The BrainE.E. Functional Brain SystemsFunctional Brain Systems

2.2. The Reticular Formation The Reticular Formation • Involved in arousal of the brainInvolved in arousal of the brain• Filters the flood of sensory input (99% filtered out)Filters the flood of sensory input (99% filtered out)

– Filters out repetitive, familiar or weak signalsFilters out repetitive, familiar or weak signals– Passes on unussual, strong, or significant signalsPasses on unussual, strong, or significant signals

VI. Parts of the Brain & How they work

E. http://education-portal.com/academy/lesson/parts-of-the-brain.html

VI. The BrainE.E.Functional Brain SystemsFunctional Brain Systems

3.3. The Ventricles The Ventricles Cavities Cavities within the within the brain brain through through which which cerebral-cerebral-spinal fluid spinal fluid flowsflows

Demo of Sheep Brain Dissection & Id it’s parts

http://www.youtube.com/watch?v=y7gEWzPqm94

VII. The Spinal CordA.A.Function – involved Function – involved

withwith1.1. Sensory Sensory pathways to pathways to brainbrain

2.2. Motor Motor pathways to pathways to bodybody

3.3. Spinal cord Spinal cord reflexesreflexes

VII. The Spinal CordB.B.Gray Matter Gray Matter at center of at center of

cordcord 1.1.Dorsal (posterior) hornsDorsal (posterior) horns = = cell bodies of the sensory cell bodies of the sensory neuronsneurons

2.2.Ventral (anterior) hornsVentral (anterior) horns = = cell bodies of the motor cell bodies of the motor neurons neurons

VII. The Spinal CordB.B.Gray Matter Gray Matter at center of at center of

cordcord3.3.Lateral hornsLateral horns = cell bodies = cell bodies of preganglionic neurons of of preganglionic neurons of the autonomic nervous the autonomic nervous systemsystem

VII. The Spinal CordB. Gray Matter B. Gray Matter at center of at center of

cordcord4.4.Gray commisureGray commisure = connects = connects the lateral halves of gray the lateral halves of gray mattermatter

VII. The Spinal CordC. Spinal Cord InjuriesC. Spinal Cord Injuries

1.1.Flaccid ParalysisFlaccid Paralysisa.a.occurs when there is occurs when there is

damage to lower motor damage to lower motor neurons neurons (i.e. anterior (i.e. anterior horns of gray matter)       horns of gray matter)                                 

b.b.results in a total loss of results in a total loss of muscle tone and atrophy muscle tone and atrophy of the muscle tissueof the muscle tissue

VII. The Spinal CordC. Spinal Cord InjuriesC. Spinal Cord Injuries

1.1.Spastic ParalysisSpastic Paralysisa.a.occurs when there is occurs when there is

damage to upper motor damage to upper motor neurons    neurons    

b.b.results in increased results in increased muscle tone, due to muscle tone, due to reduced inhibition of, but reduced inhibition of, but no voluntary control no voluntary control over, skeletal muscleover, skeletal muscle

VIII. CNS Protective StructuresA.A.Skull and Vertebral Skull and Vertebral

ColumnColumn1.1.Cranial Bones (8)Cranial Bones (8)2.2.Vertebral Column (33)Vertebral Column (33)

VIII. CNS Protective Structures

B.B.MeningesMeninges1.1.three, thin three, thin

membranes that membranes that completely cover completely cover the brain and the the brain and the spinal cord.spinal cord.

2.2.Spinal fluid flows in the Spinal fluid flows in the space between two of the space between two of the membranes.membranes.

3.3.Include theInclude the dura, dura, arachnoid, piaarachnoid, pia

VIII. CNS Protective StructuresB.B.MeningesMeninges3.3.Dura MatterDura Matter

a.a.Outer layer    Outer layer    b.b.In the skullIn the skull, ,

a double a double layered                      layered                      – outer layer = periosteal outer layer = periosteal

layer attached to layer attached to periosteium of skullperiosteium of skull

– inner layer = meningeal inner layer = meningeal layer is outermost brain layer is outermost brain coveringcovering

Meninges in the Brain

VIII. CNS Protective StructuresA.A.Skull and Vertebral ColumnSkull and Vertebral ColumnB.B.MeningesMeninges3.3.Dura MaterDura Mater

c.c.In vertebral columnIn vertebral column                            – Only a single layer Only a single layer

4.4.Arachnoid materArachnoid mater- - middle middle

layerlayer 5.5.Pia materPia mater - inner layer - inner layer

VIII. CNS Protective StructuresA.A.Skull and Vertebral ColumnSkull and Vertebral ColumnB.B.MeningesMeningesC.Spaces between the meningesC.Spaces between the meninges

1.Epidural1.EpiduralAbove the duraAbove the duraOnly in spinal column Only in spinal column

2.Subdural2.SubduralBetween dura and Between dura and arachanoidarachanoid

3.Subarachnoid3.Subarachnoid Between arachanoid and Between arachanoid and

piapia

VIII. CNS Protective StructuresD. VentriclesD. Ventricles 1.fluid filled cavities in 1.fluid filled cavities in

the brainthe brain2.Include:2.Include:a.a.11stst & 2 & 2ndnd or Lateral Ventricle or Lateral Ventricle: in : in the cerebral hemispheres, just the cerebral hemispheres, just above the epithalmus.above the epithalmus.

b.b.Third ventricleThird ventricle: in diencephalon: in diencephalonc.c.44thth ventricle ventricle: between the Pons : between the Pons & Cerebellum & Cerebellum

d.d.Cerebral AquaductCerebral Aquaduct: connects : connects the 3the 3rdrd to the 4 to the 4thth ventricles. ventricles.

VIII. CNS Protective StructuresD. VentriclesD. Ventricles

3. Contain 3. Contain tufts of vascular tufts of vascular tissue called thetissue called the choroid choroid plexus plexus whichwhich

a.a.Produce Produce cerebral spinal fluid cerebral spinal fluid && bb.Allows CSF to flow from .Allows CSF to flow from ventricles to surface of brain and ventricles to surface of brain and then is return to the blood. then is return to the blood.

VIII. CNS Protective StructuresE.E. Cerebral Spinal FluidCerebral Spinal Fluid

1.1.Nourishes brain and spinal Nourishes brain and spinal cordcord

2.2.Gives buoyancy to brainGives buoyancy to brainPrevents brain from being Prevents brain from being crushed by its own weightcrushed by its own weight

3.3.Produced in choroid Produced in choroid plexusesplexuses• volume = 150 mL (1/2 cup)volume = 150 mL (1/2 cup)• Replaced every 3-4 hrsReplaced every 3-4 hrs

arachanoid                      

F.F. Blood Brain BarrierBlood Brain Barrier1.1.Is the relative Is the relative

impermeability of brain impermeability of brain capillariescapillaries                     

Due to tight Due to tight junctions, junctions, and and endothelial endothelial lining of lining of blood blood vessels in vessels in brainbrain

F.F. Blood Brain BarrierBlood Brain BarrierPrevents Prevents passage of passage of proteins, blood proteins, blood borne borne metabolic metabolic wastes (urea, wastes (urea, creatine), creatine), some toxins, some toxins, most drugsmost drugsAllows passage of nutrients: Allows passage of nutrients:

glucose, essential amino acids, glucose, essential amino acids, some electrolytessome electrolytes

VIII. CNS Protective StructuresF.F. Blood Brain BarrierBlood Brain Barrier

3.3.Protects brain Protects brain against against fluctuations influctuations in – HormonesHormones– IonsIons– NutrientsNutrients– Toxic Toxic

substancessubstances

HIV

VIII. CNS DisordersA.A.MeningitisMeningitis

2.Infection of the CSF 2.Infection of the CSF – Causes inflamation of the Causes inflamation of the

meningesmeninges

1.Infection of the CSF 1.Infection of the CSF – Viral: Viral: less less

dangerousdangerous– Bacterial: Bacterial: can can

lead to brain damage, lead to brain damage, hearing loss, learning hearing loss, learning disabilities, death           disabilities, death          

VIII. CNS Protective StructuresA.A.MeningitisMeningitis

3.Symptoms 3.Symptoms – High feverHigh fever– Stiff neckStiff neck– Intolerance for light         Intolerance for light        

   

VIII. CNS Protective StructuresB.B.EncephalitisEncephalitis

1.1.Inflamation of brain tissue Inflamation of brain tissue and surrounding meningesand surrounding meninges

2.2.Cause – viral infectionsCause – viral infections3.3.OutcomeOutcome

– Destruction of gray Destruction of gray mattermatter

– Can be fatal          Can be fatal          C.C.Alzheimer DiseaseAlzheimer Disease1.1.Accumulation of plaque and Accumulation of plaque and

tangles in braintangles in brain2.2.Cause – unknownCause – unknown

VIII. CNS Protective StructuresD.D.ParkinsonParkinson

1.1.characterized by a characterized by a decrease in spontaneous decrease in spontaneous movements, gait difficulty, movements, gait difficulty, postural instability, postural instability, rigidity and tremorrigidity and tremor

2.2.Cause the degeneration of Cause the degeneration of the neurons producing the neurons producing dopaminedopamine

Dissecting a Human Brain

http://www.youtube.com/watch?v=OMqWRlxo1oQ

IX. CRANIAL AND SPINAL NERVESA.A.Cranial NervesCranial Nerves

1.1.Visible on ventral surfaceVisible on ventral surface2.2.12 pair12 pair

IX. CRANIAL AND SPINAL NERVESA.A.Cranial NervesCranial Nerves

2.2. 12 Pair12 PairI.I. Olfactory:Olfactory: smell smellII.II. Optic:Optic: vision visionIII.III.Oculomotor:Oculomotor: eye eye

movement movement pupil pupil dilationdilation

IV.IV.Trochlear:Trochlear: eye eye movementmovement

V.V. Trigeminal:Trigeminal: chewing; chewing; somatosensory (pain somatosensory (pain touch) touch) for headfor head

A. Cranial NervesA. Cranial Nerves2. 12 pair2. 12 pair

VI.VI. Abducens:Abducens: eye movement- eye movement-laterallateral

VII.VII. Facial Nerve:Facial Nerve: taste, facial taste, facial expressions, expressions,

somatosensory somatosensory from from earear

VIII.VIII.Vestibulocochlear:Vestibulocochlear: hearing hearing and balanceand balance

IX.IX. Glossopharyngeal:Glossopharyngeal: taste, taste, swallowing, swallowing,

sematosensory sematosensory from from tonguetongue

A. Cranial NervesA. Cranial Nerves2. 12 pair2. 12 pairX.X. Vegas:Vegas: GI & Heart activity; GI & Heart activity;

sensory, motor, autonomic sensory, motor, autonomic functions of viscerafunctions of viscera

XI.XI.Spinal Accessory:Spinal Accessory: head head movementmovement

XII.XII.Hypoglossal:Hypoglossal: tongue tongue musclesmuscles

Here is a mnemonic: Here is a mnemonic: OOn n OOld ld OOlympus lympus TTowering owering TTop op AA FFamous amous VVocal ocal GGerman erman VViewed iewed SSome ome HHops.ops.

IX. CRANIAL AND SPINAL NERVESB. Spinal Nerves – 31 pairB. Spinal Nerves – 31 pair

(1) Cervical (1) Cervical (2)(2) ThoracicThoracic(3)(3) LumbarLumbar(4)(4) SacralSacral(5)(5) CoccygealCoccygeal(6)(6) SciaticSciatic(7)(7) Lumbar plexusLumbar plexus(8)(8) Intercostal Intercostal (9)(9) Brachial plexusBrachial plexus(10)(10) Cervical plexusCervical plexus

IX. CRANIAL AND SPINAL NERVESB. Spinal Nerves – 31 pairB. Spinal Nerves – 31 pair

A nerve A nerve plexus is plexus is a a network network of of interwovinterwoven en nerves.nerves.

RecallRecallDivisions of the N.S.

Central N.S.Central N.S. Peripheral Peripheral N.S.N.S.

BraiBrainn

Spinal Spinal CordCord

AutonomiAutonomicc

SomatiSomaticcParasympathParasympath

eticeticSympathetSympatheticic

EfferentEfferent AfferenAfferentt

CNS PNSX. THE PERIPHERAL NS

X. THE PERIPHERAL NSA. Afferent vs EfferentA. Afferent vs Efferent

X. THE PERIPHERAL NSA. Afferent vs EfferentA. Afferent vs Efferent1.1.Afferent NSAfferent NS

a.a.Sensory neurons.Sensory neurons.ProprioceptorsProprioceptors: sensitive : sensitive to position and to position and movementmovement

b.b.Pick up stimulus and carry Pick up stimulus and carry it toward the CNSit toward the CNS

X. THE PERIPHERAL NSA. Afferent vs EfferentA. Afferent vs Efferent2.Efferent NS2.Efferent NS

a.a.Motor neuronsMotor neuronsb.b.Carry response impulses Carry response impulses

from the CNS to the from the CNS to the effectoreffector

X. THE PERIPHERAL NSA. Afferent vs EfferentA. Afferent vs Efferent3. Disorders of Afferent & 3. Disorders of Afferent &

Efferent systemsEfferent systemsa.a.Myasthenia GravisMyasthenia Gravis: :

immune system attacks immune system attacks Ach; leads to muscle Ach; leads to muscle weakness and fatigueweakness and fatigue

b.b.Multiple sclerosisMultiple sclerosis: loss of : loss of myelin sheath of motor myelin sheath of motor and sensory neurons; and sensory neurons; leads to limb weakness, leads to limb weakness, tremors, vision disorders, tremors, vision disorders, vertigovertigo

X. THE PERIPHERAL NSB. Somatic vs Autonomic NSB. Somatic vs Autonomic NS1.1.SomaticSomatic

a.a.Controls skeletal muscles.Controls skeletal muscles.b.b.Can be conscious or Can be conscious or

subconscioussubconsciousc.c.Has a single neuron between Has a single neuron between

CNS and effectorCNS and effector

X. THE PERIPHERAL NSB. Divisions of the Efferent NSB. Divisions of the Efferent NS2. Autonomic2. Autonomica.a.Controls smooth muscles of Controls smooth muscles of

viscera and glandsviscera and glandsb.b.Is subconsciousIs subconsciousc.c.Has 2 neurons b/w CNS & Has 2 neurons b/w CNS &

effector effector

X. THE PERIPHERAL NSB. Divisions of the Efferent NSB. Divisions of the Efferent NS2. Autonomic2. Autonomic

c.Has two neurons between c.Has two neurons between CNS and effector CNS and effector – Preganglionic neuronsPreganglionic neurons

Originate in spinal cordOriginate in spinal cord– Ganglion neuronsGanglion neurons

Nerve cell bodies Nerve cell bodies – Neurons in effectorNeurons in effector

X. THE PERIPHERAL NSC. Sympathetic and C. Sympathetic and

ParasympatheticParasympathetic1. Sympathetic1. Sympathetica.a.““Fight or Flight”Fight or Flight”b.b.Consists ofConsists of

– Preganglionic neuronsPreganglionic neurons– 2+ Ganglionic neurons2+ Ganglionic neurons– Specialized neurons in Specialized neurons in

adrenal gland (secretes adrenal gland (secretes hormone controlling hormone controlling production of Ach)production of Ach)

XI. Pain PerceptionA. Gate Control Theory A. Gate Control Theory 1.1.Without any stimulation, both Without any stimulation, both

large and small nerve fibers large and small nerve fibers are quiet and the inhibitory are quiet and the inhibitory interneuron (I) blocks the interneuron (I) blocks the signal in the projection neuron signal in the projection neuron (P) that connects to the brain. (P) that connects to the brain. The "gate is closed" and The "gate is closed" and therefore NO PAINtherefore NO PAIN

XI. Pain PerceptionA. Gate Control Theory A. Gate Control Theory 2.With non-painful stimulation, 2.With non-painful stimulation,

large nerve fibers are large nerve fibers are activated primarily. This activated primarily. This activates the projection activates the projection neuron (P), BUT it ALSO neuron (P), BUT it ALSO activates the inhibitory activates the inhibitory interneuron (I) which then interneuron (I) which then BLOCKS the signal in the BLOCKS the signal in the projection neuron (P) that projection neuron (P) that connects to the brain. The connects to the brain. The "gate is closed" and therefore "gate is closed" and therefore NO PAIN.NO PAIN.

XI. Pain PerceptionA. Gate Control Theory A. Gate Control Theory 3.With pain stimulation, small 3.With pain stimulation, small

nerve fibers become active. nerve fibers become active. They activate the projection They activate the projection neurons (P) and BLOCK the neurons (P) and BLOCK the inhibitory interneuron (I). inhibitory interneuron (I). Because activity of the Because activity of the inhibitory interneuron is inhibitory interneuron is blocked, it CANNOT block the blocked, it CANNOT block the output of the projection output of the projection neuron that connects with the neuron that connects with the brain. The "gate is open", brain. The "gate is open", therefore, therefore, PAIN!!PAIN!!

I = "Inhibitory Interneuron"; P = "Projection Neuron"- = inhibition (blocking); + = excitation (activation)

XI. Pain PerceptionB. Controlling Pain B. Controlling Pain 1.1.Aspirin:Aspirin: acts mostly in PNS; acts mostly in PNS;

reduces inflammationreduces inflammation2.2.Morphine:Morphine: acts in CNS to acts in CNS to

block pain messages block pain messages 3.3.Acupuncture:Acupuncture:

stimulates large stimulates large diameter fibers diameter fibers that inhibit pain that inhibit pain (closes the gate) (closes the gate)

http://www.youtube.com/watch?v=hHl1PslMc8MSheep Brain Dissection