the central nervous system. i. the brain a.the cerebrum 1. function a.thinking and consciousness...

The Central Nervous System

I. 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 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 - involved with hearing, also a role in memory and emotion processing.

Occipital Lobe - Responsible for vision. Damage to this area results in partial or complete blindness.

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


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

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

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

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

parietalparietal


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 sulcus)(posterior to central sulcus)

c.Basic Regionsc.Basic RegionsCortexCortex

• 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

A. The CerebrumA. The Cerebrum4. Cortex4. Cortex

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 sulcus)(posterior to central sulcus)

c.Basic Regionsc.Basic RegionsCortexCortex

• 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

VI. The BrainB.B.The Diencephalon The Diencephalon

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


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

Cerebral Cortex”Cerebral Cortex”for afferent for afferent

(sensory) (sensory) fibersfibersb.b.Relay station for Relay station for

sensory and motor sensory and motor impulses impulses


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 Brain

B.B.The Diencephalon The Diencephalon 3.3. HypothalamusHypothalamus

c.c.Involved in regulation ofInvolved in regulation of

d.d.Endocrine functionsEndocrine functions• Regulates pituitaryRegulates pituitary

Produces 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• FearFear• AngerAnger

B.B.The Diencephalon The Diencephalon 4.4. EpithalamusEpithalamus

a.a.Forms roof of Forms roof of 33rdrd

ventricleventricleb.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 Brain

C.C.The Brain Stem The Brain Stem 1.1. MidbrainMidbrain

a.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

VI. The Brain

C.C.The Brain Stem The Brain Stem 2.2. PonsPons

a.a.Conduction Conduction pathway pathway between between higher and higher and lower brain lower brain centerscenters

b.b.Regulates Regulates breathingbreathing

c.c.Cranial Cranial Nerves V - Nerves V - VIIVII

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 Cranial Nerves VIII - Nerves VIII - XIIXII

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 Brain

E.E.Functional Brain SystemsFunctional Brain Systems3.3. The Ventricles The Ventricles

Cavities Cavities within the within the brain brain through through which which cerebral-cerebral-spinal fluid spinal fluid flowsflows

VII. The Spinal Cord

A.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


C. 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


C. 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

ColumnColumn

1.1.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

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 – no outer layer no outer 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 dura and piaBetween dura and pia

VIII. CNS Protective StructuresD. VentriclesD. Ventricles

1.fluid filled cavities 1.fluid filled cavities in the brain in the brain

2.Include2.Include

a.a.2 Lateral Ventricles2 Lateral Ventricles: in : in the cerebral hemispheresthe cerebral hemispheres

b.b.Third ventricleThird ventricle: in : in diencephalondiencephalon

c.c.44thth ventricle ventricle: between the : between the Pons & Cerebellum Pons & Cerebellum

VIII. CNS Protective StructuresD. VentriclesD. Ventricles

3. Contain 3. Contain tufts of vascular tufts of vascular tissue called thetissue called the

choroid choroid plexusplexus

a.a.Produce Produce cerebral spinal cerebral spinal fluidfluid

b.CSF flows flows from b.CSF flows flows from ventricles to surface of ventricles to surface of brain and then is brain and then is returned to the blood. returned 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 Barrier

Prevents 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

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.MeningitisMeningitis3.Symptoms 3.Symptoms

– High feverHigh fever– Stiff neckStiff neck– Intolerance for light Intolerance for light

VIII. CNS Protective StructuresB.B.EncephalitisEncephalitis1.1.Inflamation of brain tissue Inflamation of brain tissue

and surrounding meningesand surrounding meninges2.2.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

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 Nerves

2. 12 pair2. 12 pair

VI.VI. Abducens:Abducens: eye movement eye movementVII.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 Nerves

2. 12 pair2. 12 pair

X.X. Vegas:Vegas: sensory, motor, sensory, motor, autonomic functions of autonomic functions of visceraviscera

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

XII.XII.Hypoglossal:Hypoglossal: tongue tongue musclesmusclesHere 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 PNS

X. THE PERIPHERAL NS


A. Afferent vs EfferentA. Afferent vs Efferent



1.1.Afferent NSAfferent NSa.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



2.Efferent NS2.Efferent NS

a.a.Motor neuronsMotor neurons

b.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 Efferent

3. Disorders of Afferent & 3. Disorders of Afferent & Efferent systemsEfferent systems

a.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 NS

1.1.SomaticSomatica.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. Autonomic

a.a.Controls smooth muscles of Controls smooth muscles of viscera and glandsviscera and glands

b.b.Is subconsciousIs subconsciousc.c.Has two neurons between Has two neurons between

CNS CNS and and 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


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.


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)

the central nervous system. i. the brain a.the cerebrum 1. function a.thinking and consciousness...

Documents

white matter slide

cortex b

central sulcus c

anatomy b

speech slide

epithalamus slide

lateral sulcus slide

thalamus b