Date post: | 18-Dec-2015 |
Category: |
Documents |
Upload: | garey-andrews |
View: | 243 times |
Download: | 2 times |
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
§ 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
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
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
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 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
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
§ 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)
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
§ 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