Central Nervous System Physiology

Carlos Darcy Alves Bersot TSA.SBACarlos Darcy Alves Bersot TSA.SBA MD RESPONSÁVEL PELO CET H.F.LAGOAMD RESPONSÁVEL PELO CET H.F.LAGOA

Médico Anestesiologista do Hospital Federal da Lagoa-SUSMédico Anestesiologista do Hospital Federal da Lagoa-SUSMédico Anestesiologista do Hospital Pedro Ernesto-UERJMédico Anestesiologista do Hospital Pedro Ernesto-UERJ

animalanimalorganismorganism

Nervous systemNervous system

sensory sensory neuronneuron

stimulusstimulus reactionreaction

effectoreffectorInter-Inter-

neuronneuronreceptorreceptorMotorMotor

neuronneuron

Nervous System Nervous System stimulus and reaction stimulus and reaction Nervous System Nervous System stimulus and reaction stimulus and reaction

Nervous SystemNervous SystemNervous SystemNervous System

• Central Nervous SystemCentral Nervous System brain, spinal cord: brain, spinal cord: nervous tissuenervous tissue meninges, choroid plexusmeninges, choroid plexus: : connective tissueconnective tissue

• Peripheral Nervous SystemPeripheral Nervous System nerve, ganglion, nerve plexusnerve, ganglion, nerve plexus::

Nervous TissueNervous TissueNervous TissueNervous Tissue

Cellular ElementsCellular Elements

ŸŸ Neuron (Nerve Cell)Neuron (Nerve Cell)

ŸŸ Neuroglial Cells Neuroglial Cells central neurgliacentral neurglia

astrocyte, oligodendrocyte, microglia andastrocyte, oligodendrocyte, microglia and ependymal cellependymal cell

peripheral neurogliaperipheral neuroglia Schwann cell Schwann cell in nerve and ganglionin nerve and ganglion satellite (capsular) cell satellite (capsular) cell in ganglionin ganglion

NeuronNeuronNeuronNeuron

Neuronal MorphologyNeuronal Morphology

Neuronal Cell Body (Soma)Neuronal Cell Body (Soma)

ŸŸ Nucleus Nucleus

Neuronal ProcessesNeuronal Processes

ŸŸ AxonAxon ŸŸ DendritesDendrites

Diversity of Neuronal Size and MorphologyDiversity of Neuronal Size and Morphology

Diversity ofDiversity of

NeuronalNeuronal

MorphologyMorphology

NeuronNeuronNeuronNeuron

Neuronal FunctionNeuronal Function

CommunicationCommunication

Receptor - Neuron - Effector Receptor - Neuron - Effector - - Excitability (Irritability)Excitability (Irritability) - - ConductivityConductivity through membrane through membrane in intraneuronal conductionin intraneuronal conduction

via via synapsesynapse in in interneuronal conductioninterneuronal conduction neurotransmittersneurotransmitters

SYNAPSESYNAPSESYNAPSESYNAPSE

ŸŸ Presynaptic Portion: Synaptic Button Presynaptic Portion: Synaptic Button - synaptic vesicle- synaptic vesicle

- mitochondria- mitochondria - presynaptic membrane: tubulin- presynaptic membrane: tubulin

ŸŸ Synaptic Cleft Synaptic Cleft - 20-30 nm- 20-30 nm

ŸŸ Postsynaptic PortionPostsynaptic Portion - postsynaptic membrane: actin, fodrin, spectrin- postsynaptic membrane: actin, fodrin, spectrin

- mitochondria- mitochondria

SYNAPSESYNAPSESYNAPSESYNAPSE

Myelin Sheath - MYELINMyelin Sheath - MYELIN Schwann sheathSchwann sheath• formed by wrapped plasma membrane offormed by wrapped plasma membrane of OligodendrocyteOligodendrocyte in CNS in CNS Schwann CellSchwann Cell in PNS in PNS

• Node of RanvierNode of Ranvier - Saltatory Conduction - Saltatory Conduction - - conduction velocityconduction velocity

MyelinMyelinMyelinMyelin

MyelinMyelin

Structure of fast nerve conductionStructure of fast nerve conduction

Multiple Slerosis Multiple Slerosis – disease of the myelin– disease of the myelin

Jacqueline Du PreJacqueline Du PreJacqueline Du PreJacqueline Du Preoligodendrocyteoligodendrocyte

ORGANIZAÇÃO DO SNORGANIZAÇÃO DO SNORGANIZAÇÃO DO SNORGANIZAÇÃO DO SN

Central Nervous SystemCentral Nervous System

Gray MatterGray Matter Nucleus and CortexNucleus and Cortex White MatterWhite Matter TractsTracts

Peripheral Nervous SystemPeripheral Nervous System

Nerve (Peripheral Nerve)Nerve (Peripheral Nerve) GanglionGanglion

Nerve FiberNerve Fiber

Myelinated Nerve FiberMyelinated Nerve Fiber

Axon,Axon, Myelin sheathMyelin sheath, Schwann cell, Schwann cell

Unmyelinated Nerve Fiber Unmyelinated Nerve Fiber Axon, Schwann cellAxon, Schwann cell

Connective Tissue SheathConnective Tissue Sheath

EndoneuriumEndoneurium Perineurium – blood vesselsPerineurium – blood vessels EpineuriumEpineurium

SISTEMA NERVOSO PERIFÉRICOSISTEMA NERVOSO PERIFÉRICOSISTEMA NERVOSO PERIFÉRICOSISTEMA NERVOSO PERIFÉRICO

Receptor Receptor

EndingsEndings

TERMINAÇÕES EFERENTESTERMINAÇÕES EFERENTESSomatic Efferent EndingsSomatic Efferent Endings

Neuromuscular JunctionNeuromuscular Junction (Myoneural Junction, Motor End (Myoneural Junction, Motor End

Plate)Plate)

Autonomic Efferent Autonomic Efferent

EndingsEndings

Endings on smooth muscle Endings on smooth muscle

and blood vesselsand blood vessels

Somatic Efferent EndingsSomatic Efferent Endings

Neuromuscular JunctionNeuromuscular Junction (Myoneural Junction, Motor End (Myoneural Junction, Motor End

Plate)Plate)

Autonomic Efferent Autonomic Efferent

EndingsEndings

Endings on smooth muscle Endings on smooth muscle

and blood vesselsand blood vessels

NeuromuscularNeuromuscularJunctionJunction

(Myoneural Junction,(Myoneural Junction,

Motor End Plate)Motor End Plate)

NeuromuscularNeuromuscularJunctionJunction

(Myoneural Junction,(Myoneural Junction,

Motor End Plate)Motor End Plate)

NMJNMJNMJNMJ

Myasthenia GravisMyasthenia GravisMyasthenia GravisMyasthenia Gravis

• muscle weaknessmuscle weakness

• autoimmune disease autoimmune disease with autoantibodieswith autoantibodies against against Ach receptorAch receptor

• treated withtreated with AchT inhibitorsAchT inhibitors, , thymectomy, and thymectomy, and corticosteroidscorticosteroids

Defects in NMDefects in NM

TransmissionTransmission

before treatment after treatmentbefore treatment after treatment

Autonomic Efferent EndingsAutonomic Efferent EndingsAutonomic Efferent EndingsAutonomic Efferent Endings

Brain RegionsBrain Regions

1. Cerebrum

2. Diencephalon

3. Brainstem

4. Cerebellum

Cerebellum

CerebrumCerebrum• O cérebro humano

contém cerca de 100 bilhões de neurônios, ligados por mais de 10,000 conexões sinápticas .

• Corpo caloso• Massa Cinzenta e

Branca.• Giros e Sulcos

• Deeper grooves called fissures separate large regions of the brain.– The median longitudinal fissure separates the cerebral hemispheres.– The transverse fissure separates the cerebral hemispheres from the

cerebellum below.• Deep sulci divide each hemisphere into 5 lobes:

– Frontal, Parietal, Temporal, Occipital, and Insula

• The central sulcus separates the frontal lobe from the parietal lobe.– Bordering the central sulcus are 2 important gyri, the precentral

gyrus and the postcentral gyrus.

• The occipital lobe is separated from the parietal lobe by the parieto-occipital sulcus.

• The lateral sulcus outlines the temporal lobe.– The insula is buried deep within the lateral sulcus.

Where’s the insula?

Cerebral Cerebral CortexCortex

• 3 types of functional areas:1. Motor Control voluntary

motor functions

2. Sensory Allow for conscious recognition of

stimuli

3. Association Integration

Cortical Motor AreasCortical Motor Areas

1. Primary Motor Cortex

2. Premotor Cortex

3. Broca’s Area

Primary motor cortex

Broca’s Area

Premotor cortex

Frontal Eye Field

Primary (Somatic) Motor CortexPrimary (Somatic) Motor Cortex

• Located in the precentral gyrus of each cerebral hemisphere.

• Contains large neurons (pyramidal cells) which project to SC neurons which eventually synapse on skeletal muscles – Allowing for voluntary

motor control.– These pathways are known

as the corticospinal tracts or pyramidal tracts.

Panfiled?

Premotor CortexPremotor Cortex• Located just anterior to

the primary motor cortex.• Involved in learned or

patterned skills.• Involved in planning

movements.• How would damage to

the primary motor cortex differ from damage to the premotor cortex?

Broca’s AreaBroca’s Area

• Typically found in only one hemisphere (often the left), anterior to the inferior portion of the premotor cortex.

• Directs muscles of tongue, and throat that are used in speech production.

• Involved in planning speech production and possibly planning other activities.

Sensory AreasSensory Areas

• Found in the parietal, occipital, and temporal lobes.

1. Primary somatosensory cortex2. Somatosensory association cortex3. Visual areas4. Auditory areas5. Olfactory cortex6. Gustatory cortex7. Vestibular cortex

Primary Somatosensory CortexPrimary Somatosensory Cortex

• Found in the postcentral gyrus.

• Neurons in this cortical area receive info from sensory neurons in the skin and from proprioceptors which monitor joint position.

• Contralateral input.

Somatosensory Association Somatosensory Association CortexCortex

• Found posterior to the primary somatosensory cortex

• Synthesizes multiple sensory inputs to create a complete comprehension of the object being felt.– How would damage to

this area differ from damage to the primary somatosensory cortex?

Primary Visual CortexPrimary Visual Cortex

• Found in the posterior and medial occipital lobe.

• Largest of the sensory cortices. – What does this

suggest?

• Contralateral input.

Association Association AreasAreas

• Allows for analysis of sensory input.

• Multiple inputs and outputs. Why?

1. Prefrontal cortex

2. Language areas

3. General interpretation area

4. Visceral association area

Prefrontal Prefrontal CortexCortex

• Anterior frontal lobes• Involved in analysis,

cognition, thinking, personality, conscience, & much more.

• What would a frontal lobotomy result in?

• Look at its evolution

Phineas Gage’s lesion reconstructedPhineas Gage’s lesion reconstructed(H. Damasio and R. Frank, 1992)(H. Damasio and R. Frank, 1992)

Language AreasLanguage Areas• Large area for language understanding and production surrounding the lateral sulcus in the left (language-dominant) hemisphere

• Includes:– Wernicke’s area

understanding oral/written words

– Broca’s area speech production

NEGLIGENCIA

Basal NucleiBasal Nuclei

• Components of the extrapyramidal system which provides subconscious control of skeletal muscle tone and coordinates learned movement patterns and other somatic motor activities.

• Doesn’t initiate movements but once movement is underway, they assist in the pattern and rhythm (especially for trunk and proximal limb muscles

• Set of nuclei deep within the white matter.

• Includes the:– Caudate Nucleus– Lentiform Nucleus

• Globus pallidus• Putamen

Basal Ganglia Components Basal Ganglia Components Basal Ganglia Components Basal Ganglia Components

Muhammad Ali in Alanta OlympicMuhammad Ali in Alanta Olympic

Parkinson’s Parkinson’s DiseaseDisease

Disease of mesostriatal Disease of mesostriatal dopaminergic systemdopaminergic system

normalnormal

SYDENHAM’S CHOREASYDENHAM’S CHOREASYDENHAM’S CHOREASYDENHAM’S CHOREA

- Complication of- Complication of Rheumatic FeverRheumatic Fever- Fine, disorganized , and - Fine, disorganized , and random movements ofrandom movements of extremities, face andextremities, face and tonguetongue- Accompanied by - Accompanied by Muscular HypotoniaMuscular Hypotonia--

Clinical FeatureClinical Feature

Principal Pathologic Lesion: Principal Pathologic Lesion: Corpus StriatumCorpus Striatum

Clinical FeatureClinical Feature

Principal Pathologic Lesion:Principal Pathologic Lesion:

Corpus Striatum (esp. caudate nucleus)Corpus Striatum (esp. caudate nucleus) and Cerebral Cortexand Cerebral Cortex

- Predominantly - Predominantly autosomal dominantlyautosomal dominantly inherited chronic fatal diseaseinherited chronic fatal disease (Gene: chromosome 4)(Gene: chromosome 4)

HUNTINGTON’S CHOREAHUNTINGTON’S CHOREA

DiencephalonDiencephalon

• Forms the central core of the forebrain

• 3 paired structures:

1. Thalamus

2. Hypothalamus

3. Epithalamus

ThalamusThalamus• 80% of the diencephalon

• Sensory retransmission station where sensory signals can be edited, sorted, and routed.

• Also has profound input on motor (via the basal ganglia and cerebellum) and cognitive function.

HypothalamusHypothalamus• Functions:

– Autonomic regulatory center• Influences HR, BP, resp. rate,

GI motility, pupillary diameter.• Can you hold your

breath until you die?

– Emotional response• Involved in fear, loathing, pleasure• Drive center: sex, hunger

– Regulation of body temperature– Regulation of food intake

• Contains a satiety center

– Regulation of water balance and thirst– Regulation of sleep/wake cycles– Hormonal control

• Releases hormones that influence hormonal secretion from the anterior pituitary gland.

• Releases oxytocin and vasopressin

EpithalamusEpithalamus

• Above the thalamus• Contains the pineal

gland which releases melatonin (involved in sleep/wake cycle and mood).

CerebellumCerebellum• Lies inferior to the cerebrum and

occupies the posterior cranial fossa.

• 2nd largest region of the brain.• 10% of the brain by volume, but it

contains 50% of its neurons

• Has 2 primary functions:1. Adjusting the postural muscles of the body

• Coordinates rapid, automatic adjustments, that maintain balance and equilibrium

2. Programming and fine-tuning movements controlled at the subconscious and conscious levels• Refines learned movement patterns by regulating activity of both

the pyramidal and extrapyarmidal motor pathways of the cerebral cortex

CerebellumCerebellum

• The cerebellum can be permanently damaged by trauma or stroke or temporarily affected by drugs such as alcohol.

• These alterations can produce ataxia – a disturbance in balance.

Cerebellar Cerebellar AtaxiaAtaxia

ROMBERGROMBERG

PonsPons

The bulging center part of the brain stem

Mostly composed of fiber tracts

Includes nuclei involved in the control of breathing

Medulla OblongataMedulla Oblongata The lowest part of the brain stem Merges into the spinal cord Includes important fiber tracts Contains important control centers

Heart rate control Blood pressure regulation Breathing Vomiting

Spinal segment Spinal segment

C8, T12, L5, S5, Cx1C8, T12, L5, S5, Cx1

Anterior (Ventral) RootAnterior (Ventral) RootPosterior (Dorsal) RootPosterior (Dorsal) Root Dorsal Root (Spinal) GanglionDorsal Root (Spinal) Ganglion

Periosteum of VertebraPeriosteum of Vertebra

- - Epidural Space Epidural Space ----------------- ----------------- epidural anesthesiaepidural anesthesia

Dura Mater Spinalis Dura Mater Spinalis

Arachnoid MembraneArachnoid Membrane - - Subarachnoid Space --------Subarachnoid Space -------- Lumbar Puncture Lumbar Puncture

Spinal AnesthesiaSpinal Anesthesia

Pia Mater SpinalisPia Mater Spinalis

Periosteum of VertebraPeriosteum of Vertebra

- - Epidural Space Epidural Space ----------------- ----------------- epidural anesthesiaepidural anesthesia

Dura Mater Spinalis Dura Mater Spinalis

Arachnoid MembraneArachnoid Membrane - - Subarachnoid Space --------Subarachnoid Space -------- Lumbar Puncture Lumbar Puncture

Spinal AnesthesiaSpinal Anesthesia

Pia Mater SpinalisPia Mater Spinalis

Spinal Cord MeningesSpinal Cord Meninges Spinal Cord MeningesSpinal Cord Meninges

Arterial SupplyArterial Supply

- Spinal Arteries- Spinal Arteries

Anterior (1) & Posterior (2) Spinal ArteryAnterior (1) & Posterior (2) Spinal Artery

from from Vertebral arteryVertebral artery

- Radicular Arteries ----- Segmental arteries- Radicular Arteries ----- Segmental arteries

from from Vertebral, Ascending Cervical, Intercostal andVertebral, Ascending Cervical, Intercostal and

Lumbar Artery Lumbar Artery

Arterial SupplyArterial Supply

- Spinal Arteries- Spinal Arteries

Anterior (1) & Posterior (2) Spinal ArteryAnterior (1) & Posterior (2) Spinal Artery

from from Vertebral arteryVertebral artery

- Radicular Arteries ----- Segmental arteries- Radicular Arteries ----- Segmental arteries

from from Vertebral, Ascending Cervical, Intercostal andVertebral, Ascending Cervical, Intercostal and

Lumbar Artery Lumbar Artery

Spinal Cord Spinal Cord Vascular SupplyVascular Supply Spinal Cord Spinal Cord Vascular SupplyVascular Supply

anterior spinal arteryanterior spinal artery segmental arteries segmental arteries

5. Adamkiwicz artery5. Adamkiwicz artery

Spinothalamic TractSpinothalamic Tract Modality: Modality: Pain & Temperature Sensation, Light Touch Pain & Temperature Sensation, Light Touch

Receptor: Receptor: Free Nerve Ending Free Nerve Ending

Ist Neuron: Ist Neuron: Dorsal Root Ganglion (Spinal Ganglion)Dorsal Root Ganglion (Spinal Ganglion) Posterior Root Posterior Root

2nd Neuron: 2nd Neuron: Dorsal Horn Dorsal Horn (Lamina I, IV, V)(Lamina I, IV, V)

Spinothalamic Tract - (Spinal Lemniscus)Spinothalamic Tract - (Spinal Lemniscus)

3rd Neuron: 3rd Neuron: Thalamus (VPL) Thalamus (VPL) Internal Capsule ----- Corona Radiata Internal Capsule ----- Corona Radiata

Termination: Termination: Primary Somesthetic Area (S I) &Primary Somesthetic Area (S I) &

Diffuse Widespread Cortical RegionDiffuse Widespread Cortical Region

Spinothalamic TractSpinothalamic Tract Modality: Modality: Pain & Temperature Sensation, Light Touch Pain & Temperature Sensation, Light Touch

Receptor: Receptor: Free Nerve Ending Free Nerve Ending

Ist Neuron: Ist Neuron: Dorsal Root Ganglion (Spinal Ganglion)Dorsal Root Ganglion (Spinal Ganglion) Posterior Root Posterior Root

2nd Neuron: 2nd Neuron: Dorsal Horn Dorsal Horn (Lamina I, IV, V)(Lamina I, IV, V)

Spinothalamic Tract - (Spinal Lemniscus)Spinothalamic Tract - (Spinal Lemniscus)

3rd Neuron: 3rd Neuron: Thalamus (VPL) Thalamus (VPL) Internal Capsule ----- Corona Radiata Internal Capsule ----- Corona Radiata

Termination: Termination: Primary Somesthetic Area (S I) &Primary Somesthetic Area (S I) &

Diffuse Widespread Cortical RegionDiffuse Widespread Cortical Region

Spinal Cord Ascending TractsSpinal Cord Ascending Tracts Spinal Cord Ascending TractsSpinal Cord Ascending Tracts

Spinothalamic TractSpinothalamic TractSpinothalamic TractSpinothalamic Tract

spinothalamicspinothalamictracttract

anterior whiteanterior whitecommissurecommissure

posterior rootposterior root

decussationdecussation

- - contralateralcontralateral loss of pain and temperature loss of pain and temperature sensation sensation below below the level of lesionthe level of lesion

Spinocerebellar TractSpinocerebellar Tract

Modality: Modality: Unconscious Proprioception Unconscious Proprioception

Receptor: Receptor: Golgi tendon organ, muscular fuseGolgi tendon organ, muscular fuse

Ist Neuron: Ist Neuron: Dorsal Root Ganglion (Spinal Ganglion)Dorsal Root Ganglion (Spinal Ganglion) Posterior Root , Posterior Root ,

2nd Neuron: 2nd Neuron: 1. Clarke’s column 1. Clarke’s column Posterior Spinocerebellar TractPosterior Spinocerebellar Tract

2. Accessory Cuneate Nucleus2. Accessory Cuneate Nucleus Cuneocerebellar Tract Cuneocerebellar Tract

3. Posterior Horn3. Posterior Horn Anterior Spinocerebellar r TractAnterior Spinocerebellar r Tract

Termination: Termination: Cerebellar CortexCerebellar Cortex