Chapter 5Chapter 5RESPIRATIONRESPIRATIONRESPIRATIONRESPIRATION

IntroductionIntroduction

Containing:Containing: inspiration & expirationinspiration & expiration

Functions: Functions:

OObtain Obtain O22 from external environment from external environment

RRemove COemove CO22 form the body form the body

Respiratory processes: Respiratory processes:

PPulmonary ventilationulmonary ventilation

GGas exchange in the lungas exchange in the lung

GGas transport in the bloodas transport in the blood

GGas exchange in the tissueas exchange in the tissue

Respiratory Respiratory processesprocesses

§ 1. Pulmonary ventilation § 1. Pulmonary ventilation

DefinitionDefinition

Principles of pulmonary ventilationPrinciples of pulmonary ventilation

** Driving forceDriving force

DDirectirect ~:~: pressure changes in alveolipressure changes in alveoli

SSourceource ~: ~: contraction of respiratory musclescontraction of respiratory muscles

IInspiratory muscles:nspiratory muscles:

DDiaphragm, iaphragm, EExternal intercostal musclexternal intercostal muscle

EExpiratory muscles:xpiratory muscles:

DDiaphragm, iaphragm, EExt- & xt- & IInternal intercostalsnternal intercostals

AAccessoryccessory respiratory musclesrespiratory muscles

Respiratory movementRespiratory movement

TypesTypes of respirationof respiration

EEupneaupnea && FForcedorced breathing (breathing (DDeepeep breathing)breathing)

AAbdominalbdominal && TThoracichoracic breathingbreathing

PrinciplesPrinciples of pulmonary ventilationof pulmonary ventilation

CContraction ontraction ((RRelaxation)elaxation) of inspiratory of inspiratory

musclesmusclesEExpansionxpansion ((RReduction) eduction) of thoracicof thoracic

cavitycavity(?)(?)DDistensionistension ((RRecoil)ecoil) of alveoliof alveoli

IIntrapulmonary pressurentrapulmonary pressure(())<<(>)(>) atmo- atmo-

sphericspheric pressurepressureAAir flows ir flows intointo (out of)(out of) the the

alveolialveoli

IntrapulmonaryIntrapulmonary pressure pressure IInspiratorynspiratory phase: phase: <1 atm<1 atm EExpiratory phase:xpiratory phase: >1 atm>1 atm AAt the end of inspiration or expiration:t the end of inspiration or expiration: =1 atm=1 atmIntrapleuralIntrapleural pressure pressure CConceptoncept && CChanges during respiratory cyclehanges during respiratory cycle MMore negative as inspiratory processingore negative as inspiratory processing LLess negative as expiratory processingess negative as expiratory processing MMeasurementeasurement && EExpressionxpression DDirect & irect & IIndirect measurementndirect measurement 775775 mmHg or mmHg or 55 mmHg mmHg AAlways < 1 atm under static conditionlways < 1 atm under static condition

Changes of intrapulmonary & intrapleural pChanges of intrapulmonary & intrapleural pressure during respiratory cycleressure during respiratory cycle

FFormationormation

IAP & PRF has opposite directions, soIAP & PRF has opposite directions, so

IPP=IAPIPP=IAPPPRFRF

At the end of insp- & expiration, soAt the end of insp- & expiration, so

IPP=ASPIPP=ASPPPRFRF

If ASP=0, If ASP=0, IPP=0IPP=0PPRF= RF= PPRFRF

IPP:IPP: intrapleural pressure intrapleural pressure

IAP:IAP: intra alveolar pressure intra alveolar pressure

PRF:PRF: pulmonary recoil force pulmonary recoil force

ASP:ASP: atmospheric pressure atmospheric pressure

Formation of Formation of intrapleural intrapleural negative presnegative pressuresure

SSignificanceignificance

PPhysiological hysiological ~~

DDistend the lung & istend the lung & MMake inspiration easier ake inspiration easier

PPromote venous & lymph return in the chestromote venous & lymph return in the chest

PPathological athological ~ (~ (PneumothoraxPneumothorax))

CCollapse the lung & ollapse the lung & MMake inspiration difficultake inspiration difficult

AAffect venous & lymph returnffect venous & lymph return

FFatal in pulmonary & circulatory failure casesatal in pulmonary & circulatory failure cases

IImportancemportance

KKeep the interpleural cavity eep the interpleural cavity hermetically sealedhermetically sealed

** Resistance to breathingResistance to breathing

Elastic Elastic ~ of the lung~ of the lung

EElastic ~ & lastic ~ & CCompliance ompliance

CCLL=1/R=1/RLL==VVLL//PPLL(L/cmH(L/cmH22O)O)

SStatic compliance (Ctatic compliance (Cstst) of the lung) of the lung

SS shaped curve, divided into 3 portionsshaped curve, divided into 3 portions

FFlattened upper portionlattened upper portion

SSteep middle portionteep middle portion

FFlattened lower portionlattened lower portion

SSpecial compliance (Cpecial compliance (Cspsp))

CCspsp = C = CLL/TLC/TLC

Static compliance (CStatic compliance (Cstst) of the lung) of the lung

S shaped compliance curve of the lungS shaped compliance curve of the lung

SSource of elastic ~ of the lungource of elastic ~ of the lung

EElastic tissuelastic tissue (1/3) &(1/3) & AAlveolar surface tensionlveolar surface tension (2/3)(2/3)

PPulmonary surfactantulmonary surfactant

NNature:ature: AA lipoprotein,lipoprotein, MMain lip component is DPLain lip component is DPL

CCharacteristics:haracteristics: BBothoth hydro-philia & -phobicityhydro-philia & -phobicity

SSource:ource: TType II alveolar epithelial cellsype II alveolar epithelial cells

DDistribution:istribution: IInnernner surface of the alveolisurface of the alveoli

AAction:ction: RReduceeduce the alveolar surface tensionthe alveolar surface tension

SSignificance:ignificance: DDecrease the inspiratory resistance,ecrease the inspiratory resistance,

SStabilizetabilize the volume & pressure in the alveoli, the volume & pressure in the alveoli,

PPreventrevent pulmonary edemapulmonary edema

Pulmonary Pulmonary compliance compliance curve when curve when filled with air filled with air or salineor saline

Pulmonary Pulmonary recoil force in recoil force in the big & the big & small alveoli small alveoli communicated communicated each other each other

Elastic Elastic ~ of the thorax~ of the thorax

CharacteristicsCharacteristics of elastic of elastic resistance of the thoraxresistance of the thorax

Elastic Elastic resistanceresistance

Pulmonary Pulmonary capacitycapacity InspirationInspiration ExpirationExpiration

ThoraxThorax >67%TLC>67%TLC ResistanceResistanceDrivingDriving forceforce

ThoraxThorax =67%TLC=67%TLC

ThoraxThorax <67%TLC<67%TLC Driving Driving forceforce ResistanceResistance

LungLung For everFor ever ResistanceResistance Driving Driving forceforce

Non-elastic resistanceNon-elastic resistance

Airway resistance (main)Airway resistance (main)

Definition & Calculation Definition & Calculation

)s/L(Q

)OcmH(PPR

A

IAPASPAW

2 )s/L(Q

)OcmH(PPR

A

IAPASPAW

2

FactorsFactors affecting the airway resistance: affecting the airway resistance:

VVelocity of air flowelocity of air flow: R: RAWAW VVAFAF

TType of air flow:ype of air flow: LLaminar flow & aminar flow & TTurbulenceurbulence

DDiameter of airway:iameter of airway: TTransmural pressure; ransmural pressure;

RRadiate traction by pulmonary parenchyma;adiate traction by pulmonary parenchyma;

AAutonomic nervous system; utonomic nervous system; CChemical factors hemical factors

Differences between the large & small airwayDifferences between the large & small airway

Large airwayLarge airway Small airwaySmall airway

DDiameteriameter > 2 mm> 2 mm < 2 mm< 2 mm TTotal cross-otal cross- sectional areasectional area SmallSmall LargeLarge

AAir flow velocityir flow velocity FasterFaster SlowerSlower

TType of air flowype of air flow TurbulenceTurbulence LaminarLaminar TTotal airway otal airway resistanceresistance 90%90% 10%10%

FFall illall ill Not easyNot easy EasyEasy

RResistanceesistance > 2 cmH> 2 cmH22OO < 2 cmH< 2 cmH22OO

Pulmonary volume & capacityPulmonary volume & capacity

** Tidal volume (TV)Tidal volume (TV)

** Inspiratory reserve volume (IRV)Inspiratory reserve volume (IRV)

** TExpiratory reserve volume (ERV)TExpiratory reserve volume (ERV)

** Residual volume (RV)Residual volume (RV)

** Inspiratory capacity (IC)Inspiratory capacity (IC)

** Functional residual capacity (FRC)Functional residual capacity (FRC)

** Vital capacity (VC)Vital capacity (VC)

** Forced vital capacity (FVC) & Forced vital capacity (FVC) &

Forced expiratory capacity (FEC)Forced expiratory capacity (FEC)

** Total lung capacity (TLC)Total lung capacity (TLC)

Pulmonary volume & capacityPulmonary volume & capacity

Forced Forced expiratory expiratory volumevolume

Pulmonary ventilation volumePulmonary ventilation volume

** Minute ventilation volumeMinute ventilation volume

** Maximal (voluntary) ventilation &Maximal (voluntary) ventilation &

Percentage of ventilation reserve volumePercentage of ventilation reserve volume

** Anatomical, Alveolar & Physiological dead Anatomical, Alveolar & Physiological dead

space, Alveolar ventilationspace, Alveolar ventilation

MVV=TV MVV=TV ×RF×RF; AV=(TV; AV=(TVDSV)DSV)×RF×RF

MVV=TVMVV=TV/2/2××22RFRF;; AVAV=(TV=(TV/2/2DSV)DSV)××22RFRF

MVV=MVV=22TVTV×RF×RF/2/2;; AVAV=(=(22TVTVDSV)DSV)×RF×RF/2/2

%V

VVPVRV

MAX

PPMMAX 100

%

V

VVPVEV

MAX

PPMMAX 100

%V

VVPVEV

MAX

PPMMAX 100

§ 2. Respiratory gas exchange § 2. Respiratory gas exchange

Mechanisms of gas exchangeMechanisms of gas exchange

** Driving force: Driving force: Partial pressure of OPartial pressure of O22 or CO or CO22

** Mode: Mode: Diffusion of gasDiffusion of gas

** Condition: Condition: Permeability of membranePermeability of membrane

Processes of gas exchangeProcesses of gas exchange

PoPo22 & & PcoPco22 in alveoli, blood & tissuein alveoli, blood & tissue (mmHg)(mmHg)Alveolar airAlveolar air Venous bloodVenous blood Arterial bloodArterial blood TissueTissue

PoPo22 104104 4040 100100 3030

PcoPco22 4040 4646 4040 5050

Processes of Processes of gas exchangegas exchange

Factors affecting gas exchangeFactors affecting gas exchange

** Diffusion rate of gas Diffusion rate of gas

** Ventilation/perfusion ratio (V/Q)Ventilation/perfusion ratio (V/Q)

DDefinitionefinition & its & its normal value normal value (0.84)(0.84)

IfIf VV/Q /Q > 0.84: > 0.84: Alveolar dead space Alveolar dead space

VV/Q /Q < 0.84: < 0.84: Functional A-V shunt Functional A-V shunt

AAnoxia noxia occurs more easily than occurs more easily than COCO22 retention retention

AAffecting by ffecting by gravity gravity when a person standswhen a person stands

MWd

SATPD

MWd

SATPD

Respiratory Respiratory membranemembrane

Ventilation/Ventilation/perfusion perfusion ratio (V/Q)ratio (V/Q)

§ 3. Gas transport in the blood § 3. Gas transport in the blood

Oxygen transportOxygen transport

** Forms of transportForms of transport

PPhysically diffusion & hysically diffusion & CCombination with Hbombination with Hb

DN:DN:

2222

2 OHbHbOOHbPolow

Pohigh 2222

2 OHbHbOOHbPolow

Pohigh

** Characteristics of Hb combined with OCharacteristics of Hb combined with O22

FFast, ast, rreversible, eversible, nneed not enzyme, eed not enzyme, ooxygenatexygenate

with Fewith Fe2+2+, , OO22 combined combined with Hb is with Hb is 44:1, :1,

SS shaped shaped oxygenoxygen dissociation curvedissociation curve

** Oxygen Oxygen capacitycapacity, , contentcontent & & saturationsaturation

** CyanosisCyanosis & & carbon monoxidecarbon monoxide poisoning poisoning

** Oxygen dissociation curveOxygen dissociation curve

DDefinition & why it is in S shapedefinition & why it is in S shaped

PPhysiological advantages of S shaped curvehysiological advantages of S shaped curve

TThe flattened upper portion (60~100 mmHg)he flattened upper portion (60~100 mmHg)

TThe steep middle portion (40~60 mmHg)he steep middle portion (40~60 mmHg)

TThe steep lower portion (15~40 mmHg)he steep lower portion (15~40 mmHg)

FFactors affecting oxygen dissociation curveactors affecting oxygen dissociation curve

CConceptoncept of of PP5050, , aaffinity to Offinity to O22, , rright or ight or lleft shifteft shift

FFactors:actors: pHpH & & PcoPco22 ((Bohr effectBohr effect), ), ttemperature,emperature,

22, 3-DPG,, 3-DPG, o others (thers (FFee2+2+FeFe3+3+, , CCO) O)

OxygenOxygen dissociation curvedissociation curve

Factors affecting oxygen dissociation curveFactors affecting oxygen dissociation curve

Carbon dioxide transportCarbon dioxide transport

** Forms of transportForms of transport

PPhysically diffusionhysically diffusion

CCombination with Hbombination with Hb

HCOHCO33 & & HHbNHCOOHHHbNHCOOH

HHCOCOHOHCO CA33222

HHCOCOHOHCO CA33222

** Carbon dioxide dissociation curveCarbon dioxide dissociation curve

** Influence of combination of Hb with OInfluence of combination of Hb with O22 on on

COCO22 transport ( transport (Haldane effectHaldane effect))

2222 OHHbNHCOOHCOHOHbNH 2222 OHHbNHCOOHCOHOHbNH

Carbon dioxide transport in the bloodCarbon dioxide transport in the blood

Carbon dioxide dissociation curveCarbon dioxide dissociation curve

§ 4. Regulation of respiratory activity § 4. Regulation of respiratory activity Respiratory centersRespiratory centers ** In the spinal cordIn the spinal cord ** In the lower brain stemIn the lower brain stem Research techniques:Research techniques: Brain stem transection, Microelectrode, etc.Brain stem transection, Microelectrode, etc. Medullary oblongata:Medullary oblongata: DRG:DRG: VL-NTSVL-NTS VRG:VRG: cVRG, i(or r)VRG, Böt C, pre-Böt CcVRG, i(or r)VRG, Böt C, pre-Böt C Pons:Pons: PPneumotaxicneumotaxic center, center, PPBKF (NPBM+KBKF (NPBM+KF)F) ** In the higher brain: In the higher brain: CCerebral cortex, erebral cortex, LLimbic imbic system, system, HHypothalamusypothalamus

Research on respiratory centers: BResearch on respiratory centers: Brain stem transectionrain stem transection

Formation of respiratory rhythmFormation of respiratory rhythm ** A key region of its generation: Pre-Böt C A key region of its generation: Pre-Böt C ** Central inspiratory activity generator (CIAG) Central inspiratory activity generator (CIAG) & & Inspiratory off switchInspiratory off switch mechanismmechanism (IOS) (IOS) Respiratory reflexesRespiratory reflexes ** Pulmonary stretch reflex (Hering-Breuer ~)Pulmonary stretch reflex (Hering-Breuer ~) Inflation Inflation & & deflation reflexdeflation reflex ** ChemoreflexChemoreflex Peripheral & central Peripheral & central chemoreceptorschemoreceptors

Respiratory regulation of Respiratory regulation of COCO22, H, H++ && O O22

Interaction Interaction of COof CO22, H, H++ & O & O22 on the regulation on the regulation ** Proprioceptive reflexProprioceptive reflex of respiratory muscles of respiratory muscles

PBKFPBKF

CIAG, Insp. NeuronsCIAG, Insp. Neurons IOSIOS

Insp. Muscular NeuronsInsp. Muscular Neurons

Insp. movementInsp. movement PSRPSR

++

++++

++

++

++

++

−−

Insp. center Insp. center (medulla)(medulla)

Insp. Neurons Insp. Neurons (spinal cord)(spinal cord)

Contraction Contraction (or (or relaxation) relaxation) of insp. of insp.

musclesmuscles

Inflation Inflation (or (or Deflation)Deflation)

Inflation receptor Inflation receptor or or deflation receptordeflation receptor

Off switch mechanismOff switch mechanism++ −−−−

ⅩⅩ ⅩⅩ

PPaacoco22[H[H++]]aa

PPaaoo22

Carotid & Carotid & aortic bodiesaortic bodiesCarotid & Carotid &

aortic bodiesaortic bodies Resp. Center Resp. Center (Medulla)(Medulla)

Resp. Center Resp. Center (Medulla)(Medulla)

BBBBBB

COCO22+H+H22OOCentral chemoCentral chemo

receptorreceptorCentral chemoCentral chemo

receptorreceptor

Resp. Resp.

A A & &

F F

HCOHCO33

HH++

COCO22

OO22 OO22

HH++ HH++

CSFCSF BloodBlood

((−−))

A: amplitude; F: frequencyA: amplitude; F: frequency

BBB: blood-brain barrierBBB: blood-brain barrier

CSF: cerebrospinal fluid CSF: cerebrospinal fluid

Respiratory regulation of CORespiratory regulation of CO22, H, H++ & O & O22