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1、Chapter 5 RespirationWhen you can not breath, nothing else matters Slogan of the American Lung Association1Respiration医疗9/9/2024Chapter 5 RespirationWhen youRespiration is the process by which the body takes in and utilizes oxygen (O2) and gets rid of carbon dioxide (CO2).2Respiration医疗9/9/2024Respi
2、ration is the process by An Overview of Key Steps in Respiration3Respiration医疗9/9/2024An Overview of Key Steps in ReRespiration can be divided into four major functional eventsVentilation: Movement of air into and out of lungsGas exchange between air in lungs and bloodTransport of oxygen and carbon
3、dioxide in the bloodInternal respiration: Gas exchange between the blood and tissues4Respiration医疗9/9/2024Respiration can be divided intRespiratory System Functions Gas exchange: Oxygen enters blood and carbon dioxide leavesRegulation of blood pH: Altered by changing blood carbon dioxide levelsVoice
4、 production: Movement of air past vocal folds makes sound and speechOlfaction: Smell occurs when airborne molecules drawn into nasal cavityProtection: Against microorganisms by preventing entry and removing themMetabolism: Synthesize and metabolize different compounds (Nonrespiratory Function of the
5、 Lung)5Respiration医疗9/9/2024Respiratory System Functions GSection I VENTILATION 6Respiration医疗9/9/2024Section I VENTILATION 6ROccurs because the thoracic cavity changes volumeInsipiration uses external intercostals and diaphragmExpiration is passive at rest, but uses internal intercostals and abdomi
6、nals during severe respiratory loadBreathing rate is 10-20 breaths / minute at rest, 40 - 45 at maximum exercise in adultsVentilation7Respiration医疗9/9/2024Occurs because the thoracic ca Thoracic Walls and Muscles of Respiration8Respiration医疗9/9/2024 Thoracic Walls and Muscles ofThoracic Volume9Respi
7、ration医疗9/9/2024Thoracic Volume9Respiration医疗1 Pleura10Respiration医疗9/9/2024 Pleura10Respiration医疗10/2/202Pleural fluid produced by pleural membranesActs as lubricantHelps hold parietal and visceral pleural membranes together11Respiration医疗9/9/2024Pleural fluid produced by pleu I. Alveolar Pressure
8、Changes During Respiration12Respiration医疗9/9/2024 I. Alveolar Pressure Changes Chest WallChest Wall(muscle, ribs)(muscle, ribs)Principles of BreathingFunctional Unit: Chest Wall and Lung Functional Unit: Chest Wall and Lung ConductingConductingAirwaysAirwaysDiaphragmDiaphragm(muscle)(muscle)LungsLun
9、gsGas ExchangeGas Exchange Follows Boyles Law:Follows Boyles Law:Pressure (P) x Volume (V) = ConstantPressure (P) x Volume (V) = ConstantPleural CavityPleural CavityImaginary Space betweenImaginary Space betweenLungs and chest wallLungs and chest wallPleural CavityPleural CavityVery small space Very
10、 small space Maintained at negative pressureMaintained at negative pressureTransmits pressure changes Transmits pressure changes Allows lung and ribs to slideAllows lung and ribs to slide 13Respiration医疗9/9/2024Chest WallPrinciples of BreathCWCWFollows Boyles Law: PV= CFollows Boyles Law: PV= CAt Re
11、st with mouth open PAt Rest with mouth open Pb b = P = Pi i = 0= 0D DPi iA APSPSPb bAirway OpenAirway OpenPrinciple of BreathingPrinciple of Breathing114Respiration医疗9/9/2024CWFollows Boyles Law: PV= CAtCWCWFollows Boyles Law: PV= CFollows Boyles Law: PV= CAt Rest with mouth open PAt Rest with mouth
12、 open Pb b = P = Pi i = 0= 0Inhalation: Inhalation: - - Increase Volume of Rib cage Increase Volume of Rib cage- - Decrease the pleural cavity pressure Decrease the pleural cavity pressure- Decrease in Pressure inside (P- Decrease in Pressure inside (Pi i) ) lungslungsD DPi iA APSPSPb bAirway OpenAi
13、rway OpenPrinciple of BreathingPrinciple of Breathing215Respiration医疗9/9/2024CWFollows Boyles Law: PV= CAtCWCWFollows Boyles Law: PV= CFollows Boyles Law: PV= CAt Rest with mouth open PAt Rest with mouth open Pb b = P = Pi i = 0 = 0Inhalation: Inhalation: - - P Pb b outside is now greater than P out
14、side is now greater than Pi i- Air flows down pressure gradient- Air flows down pressure gradient- - Until Pi = Pb Until Pi = PbD DPi iA APSPSPb bAirway OpenAirway OpenPrinciple of BreathingPrinciple of Breathing316Respiration医疗9/9/2024CWFollows Boyles Law: PV= CAtCWCWFollows Boyles Law: PV= CFollow
15、s Boyles Law: PV= CD DPi iA APSPSPb bAirway OpenAirway OpenAt Rest with mouth open PAt Rest with mouth open Pb b = P = Pi i = 0 = 0Exhalation: Opposite ProcessExhalation: Opposite Process- - Decrease Rib Cage Volume Decrease Rib Cage VolumePrinciple of BreathingPrinciple of Breathing417Respiration医疗
16、9/9/2024CWFollows Boyles Law: PV= CDPCWCWFollows Boyles Law: PV= CFollows Boyles Law: PV= CAt Rest with mouth open PAt Rest with mouth open Pb b = P = Pi i = 0 = 0Exhalation: Opposite ProcessExhalation: Opposite Process- - Decrease Rib Cage Volume Decrease Rib Cage Volume- - Increase in pleural Incr
17、ease in pleural cavity pressure cavity pressure - Increase P - Increase Pi iD DPi iA APSPSPb bAirway OpenAirway OpenPrinciple of BreathingPrinciple of Breathing518Respiration医疗9/9/2024CWFollows Boyles Law: PV= CAtCWCWFollows Boyles Law: PV= CFollows Boyles Law: PV= CAt Rest with mouth open PAt Rest
18、with mouth open Pb b = P = Pi i = 0 = 0Exhalation: Opposite ProcessExhalation: Opposite Process- - Decrease Rib Cage Volume Decrease Rib Cage Volume- - Increase P Increase Pi i- - Pi is greater than P Pi is greater than Pb b- - Air flows down pressure gradient Air flows down pressure gradient- - Unt
19、il P Until Pi i = P = Pb b again againD DPi iA APSPSPb bAirway OpenAirway OpenPrinciple of BreathingPrinciple of Breathing619Respiration医疗9/9/2024CWFollows Boyles Law: PV= CAtMechanisms of Breathing: How do we change the volume of the rib cage ?How do we change the volume of the rib cage ?To Inhale
20、is an ACTIVE processTo Inhale is an ACTIVE process DiaphragmRib CageRib CageContractContractDiaphragmDiaphragmVolumeVolume External Intercostal Muscles External Intercostal Muscles IntercostalsIntercostalsContractContractto Liftto LiftRibRibSpineSpineRibsRibsVolumeVolumeBoth actions occur simultaneo
21、usly otherwise not effectiveBoth actions occur simultaneously otherwise not effective20Respiration医疗9/9/2024Mechanisms of Breathing: How 21Respiration医疗9/9/202421Respiration医疗10/2/2022II Resistance of the VentilationElastic ResistanceInelastic Resistance22Respiration医疗9/9/2024II Resistance of the Ve
22、ntilati1. Elastic ResistanceA lung is an elastic sac. The thoracic wall is also an elastic element. So during inspiration the inspiratory muscles must expand the thoracic cage which are together with the elastic resistance.23Respiration医疗9/9/20241. Elastic Resistance23RespiraThe elastic forces can b
23、e divided into two parts:1)Caused by the elastic tissue of the lung and the thoracic wall 2) Caused by surface tension of the fluid that lines the inside wall of the alveoli.The elastic forces caused by surface tension are much more complex. Surface tension accounts for about two thirds of the total
24、 elastic forces in a normal lungs.24Respiration医疗9/9/2024The elastic forces can be diviSurface tension (表面张力）: a measure of the attraction force of the surface molecules per unit length of the material to which they are attached25Respiration医疗9/9/2024Surface tension (表面张力）: a measSurface TensionForc
25、e exerted by fluid in alveoli to resist distensionLungs secrete and absorb fluid, leaving a very thin film of fluid.This film of fluid causes surface tension.H20 molecules at the surface are attracted to other H20 molecules by attractive forces.Force is directed inward, raising pressure in alveoli.2
26、6Respiration医疗9/9/2024Surface TensionForce exerted bWhat is Surface Tension ?Within Fluid All forces balanceAt surfaceUnbalanced forces Generate Tension27Respiration医疗9/9/2024What is Surface Tension ?WithiSurface TensionLaw of Laplace:Pressure in alveoli is directly proportional to surface tension;
27、and inversely proportional to radius of alveoli.Pressure in smaller alveolus would be greater than in larger alveolus, if surface tension were the same in both.Insert fig. 16.1128Respiration医疗9/9/2024Surface TensionLaw of Laplace:CollapseCollapseExpandExpandEffect of Surface Tension on Alveoli sizeA
28、irAir FlowFlow29Respiration医疗9/9/2024CollapseExpandEffect of SurfacSurfactant (表面活性物质）Phospholipid produced by alveolar type II cells.Lowers surface tension.Reduces attractive forces of hydrogen bonding by becoming interspersed between H20 molecules.Surface tension in alveoli is reduced.30Respiratio
29、n医疗9/9/2024Surfactant (表面活性物质）PhospholipiArea dependence of Surfactant actionTensionTensionAreaAreaSurfactantSurfactantIncrease AreaSalineSalineSlider - Change Surface AreaSlider - Change Surface AreaSalineSalineDecreaseAreaLow S/unit AreaHigh S/unit Area31Respiration医疗9/9/2024Area dependence of Sur
30、factant Surfactant prevents alveolar collapse32Respiration医疗9/9/2024Surfactant prevents alveolar cVolume LVolume LRVRVPleural PressurePleural Pressure0 06 60 0- 30 cm H- 30 cm H2 2OO- - 15153 3Normal (with surfactant)Normal (with surfactant)Saline FilledSaline FilledWithout surfactantVolume-pressure
31、 curves of lungs filled with saline and with air (with or without surfactant)33Respiration医疗9/9/2024Volume LRVPleural Pressure060-Physiology Importance of SurfactantReduce the work of breathingStabilize alveoliPrevent collapse and sticking of alveoliMaintain the dryness of the alveoliPrevent the ede
32、ma of the alveoli34Respiration医疗9/9/2024Physiology Importance of SurfaComplianceDistensibility (Stretchability, Elasticity):Ease with which the lungs can expand.The compliance is inversely proportional to elastic resistance Change in lung volume per change in transpulmonary pressure. D DV/D DP100 x
33、more distensible than a balloon.Specific compliance (比顺应性, CL）: the compliance per unit volumeCL = pulmonary compliance/residual volume35Respiration医疗9/9/2024ComplianceDistensibility (Stre2. Inelastic ResistanceThe inelastic resistance comprises 1.airway resistance (friction) 2.pulmonary tissue resi
34、stance (viscosity and inertia). Of these the airway resistance is by far the more important both in health and disease. It account for 80%-90% of the inelastic resistance. 36Respiration医疗9/9/20242. Inelastic Resistance36RespiAirway ResistanceAirway resistance is the resistance to flow of air in the
35、airways and is due to :1) internal friction between gas molecules2)2) friction between gas molecules and the walls of the airways37Respiration医疗9/9/2024Airway ResistanceAirway resistTypes of Air Flow38Respiration医疗9/9/2024Types of Air Flow38RespirationLaminar flow is when concentric layers of gas fl
36、ow parallel to the wall of the tube. The velocity profile obeys Poiseuilles Law39Respiration医疗9/9/2024Laminar flow is when concentrPoiseuille and ResistanceAirway Radius or diameter is KEY. radius by 1/2 resistance by 16 FOLD - think bronchodilator here!40Respiration医疗9/9/2024Poiseuille and Resistan
37、ceAirwaThe gas flow in the larger airways (nose, mouth, glottis, and bronchi) is turbulentGas flow in the smaller airway is laminarBreath sounds heard with a stethoscope reflect the turbulent airflowLaminar flow is silent41Respiration医疗9/9/2024The gas flow in the larger aiAirway ResistanceAny factor
38、 that decreases airway diameter, or increases turbulence will increase airway resistance, eg:Rapid breathing: because air velocity and hence turbulence increasesNarrowing airways as in asthma (哮喘）, parasympathetic stimulation, etc.Emphysema (肺气肿）, which decreases small airway diameter during forced
39、expirationIncrease of the density and viscosity of the inspired gas also increase the airway resistance42Respiration医疗9/9/2024Airway ResistanceAny factor thControl of Airway Smooth MuscleNeural controlAdrenergic beta receptors causing dilatationParasympathetic-muscarinic receptors causing constricti
40、onNANC nerves (non-adrenergic, non-cholinergic)Inhibitory release VIP and NO bronchodilitationStimulatory bronchoconstriction, mucous secretion, vascular hyperpermeability, cough, vasodilation “neurogenic inflammation”43Respiration医疗9/9/2024Control of Airway Smooth MusclControl of Airway Smooth Musc
41、leLocal factorshistamine binds to H1 receptors-constrictionhistamine binds to H2 receptors-dilationslow reactive substance of anaphylaxis (过敏反应）- constriction-allergic response to pollenProstaglandins （前列腺速） E series - dilation Prostaglandins （前列腺素）F series - constriction 44Respiration医疗9/9/2024Cont
42、rol of Airway Smooth MusclControl of Airway Smooth Muscle (cont)Environmental pollutionsmoke, dust, sulfur dioxide, some acidic elements in smogElicit constriction of airwaysmediated by:parasympathetic reflexlocal constrictor responses45Respiration医疗9/9/2024Control of Airway Smooth MusclIII Assessme
43、nt of the Pulmonary Ventilation46Respiration医疗9/9/2024III Assessment of the PulmonarI. Pulmonary Volume and Capacity47Respiration医疗9/9/2024I. Pulmonary Volume and Capaci48Respiration医疗9/9/202448Respiration医疗10/2/2022Pulmonary VolumesTidal volume (潮气量）Volume of air inspired or expired during a normal
44、 inspiration or expiration (400 500 ml)Inspiratory reserve volume （补吸气量）Amount of air inspired forcefully after inspiration of normal tidal volume (1500 2000 ml)Expiratory reserve volume （补呼气量）Amount of air forcefully expired after expiration of normal tidal volume (900 1200 ml)Residual volume （残气量，
45、RV）Volume of air remaining in respiratory passages and lungs after the most forceful expiration (1500 ml in male and 1000 ml in female)49Respiration医疗9/9/2024Pulmonary VolumesTidal volume 50Respiration医疗9/9/202450Respiration医疗10/2/2022Pulmonary CapacitiesA Capacity is composed of two or more volumes
46、Inspiratory capacity （深吸气量）Tidal volume plus inspiratory reserve volumeFunctional residual capacity （功能残气量, FRC）Expiratory reserve volume plus the residual volumeVital capacity （肺活量, VC）Sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume Total lung capacity （肺总量, TLC）Sum o
47、f inspiratory and expiratory reserve volumes plus the tidal volume and residual volume51Respiration医疗9/9/2024Pulmonary CapacitiesA Capacity52Respiration医疗9/9/202452Respiration医疗10/2/2022RV/TLC Normally less than 0.25 Increase by the obstructive pulmonary disease (RV) Increase during the restrictive
48、lung disease (TLC)53Respiration医疗9/9/2024RV/TLC53Respiration医疗10/2/2022Minute and Alveolar VentilationMinute ventilation: Total amount of air moved into and out of respiratory system per minuteRespiratory rate or frequency: Number of breaths taken per minuteAnatomic dead space: Part of respiratory s
49、ystem where gas exchange does not take placeAlveolar ventilation: How much air per minute enters the parts of the respiratory system in which gas exchange takes place54Respiration医疗9/9/2024Minute and Alveolar VentilatioDead SpaceArea where gas exchange cannot occurIncludes most of airway volumeAnato
50、mical dead space (=150 ml)AirwaysPhysiological dead space= anatomical + non functional alveoli55Respiration医疗9/9/2024Dead SpaceArea where gas exchaBasic Structure of the LungVD DA tube = Airway A tube = Airway (Trachea Bronchi Bronchioles) (Trachea Bronchi Bronchioles) NO GAS EXCHANGENO GAS EXCHANGE
51、DEAD SPACEA thin walled Sac = AlveolusA thin walled Sac = AlveolusBlood VesselsBlood VesselsGAS EXCHANGEGAS EXCHANGEOCCURS HEREOCCURS HEREVA AFormula: Total Ventilation = Dead Space + Alveolar SpaceFormula: Total Ventilation = Dead Space + Alveolar Space V VT T = V = VD D + V+ VA A 56Respiration医疗9/
52、9/2024Basic Structure of the LungVDAPhysiological =Physiological = Anatomical Dead SpaceAnatomical Dead Space Dead Space Dead Space + + Similar Concept: Physiological Dead SpaceDiseased lungs:Healthy Lungs:Healthy Lungs:BlockedBlockedVesselVesselAdditional Dead SpaceAdditional Dead Space Anatomical
53、Dead SpaceAnatomical Dead Space = Airways (constant) = Airways (constant)V VA AV VD D57Respiration医疗9/9/2024Physiological = AnatomicaII. Measurement of Expiratory Flow - FVC58Respiration医疗9/9/2024II. Measurement of Expiratory FVC - forced vital capacity (cont)Defines maximum volume of exchangeable a
54、ir in lung (vital capacity)forced expiratory breathing maneuverrequires muscular effort and some patient trainingInitial (healthy) FVC values approx 4 litersslowly diminishes with normal aging59Respiration医疗9/9/2024FVC - forced vital capacity (cSignificantly reduced FVC suggests damage to lung tissu
55、erestrictive lung disease (fibrosis，纤维化)constructive lung diseaseloss of functional alveolar tissue FVC volume reduction trend over time (years) is key indicatorIntra-subject variability factorsagesexheightethnicityFVC - forced vital capacity (cont)60Respiration医疗9/9/2024Significantly reduced FVC su
56、ggFEV1 - forced expiratory volume (1 second) Defines maximum air flow rate out of lung in initial 1 second intervalforced expiratory breathing maneuverrequires muscular effort and some patient trainingFEV1/FVC rationormal FEV1 about 3 litersFEV1 needs to be normalized to individuals vital capacity (
57、FVC)typical normal FEV1/FVC ratio = 3 liters/ 4 liters = 0.7561Respiration医疗9/9/2024FEV1 - forced expiratory volumStandard screening measure for obstructive lung disease FEV1/FVC reduction trend over time (years) is key indicatorcalculate % predicted FEV1/FVC (age and height normalized)Reduced FEV1/
58、FVC suggests obstructive damage to lung airwaysepisodic, reversible by bronchodilator drugsprobably asthma (哮喘)continual, irreversible by bronchodilator drugsprobably COPD （chronic obstructive pulmonary disease，慢性阻塞性肺病）FEV1 - forced expiratory volume (1 second)62Respiration医疗9/9/2024Standard screeni
59、ng measure forVolume (litres)Time (sec)Forced Vital Capacity - FVCTotal Lung CapacityResidual VolumeSpirometryForced Expiratory Volume in 1 sec - FEV11 sec63Respiration医疗9/9/2024Volume (litres)Time (sec)Forceeg fibrosis / pulmonary oedema3. Assessment of RESTRICTIVE Lung DiseasesThese are diseases t
60、hat reduce the effective surface area available for gas exchangeNormal Lung VolumeLung Volume in Restrictive Disease64Respiration医疗9/9/2024eg fibrosis / pulmonary oedemREDUCEDVolume (litres)Time (sec)Vital CapacityTotal Lung CapacityResidual VolumeSpirometryRESTRICTIVE lung disease65Respiration医疗9/9
61、/2024REDUCEDVolume (litres)Time (seeg asthma / bronchitisAssessment of OBSTRUCTIVE Lung DiseasesThese are diseases that reduce the diameter of the airways and increase airway resistance -remember Resistance increases with 1/radius 4Normal Airway CalibreAirway Calibre in Obstructive Disease66Respirat
62、ion医疗9/9/2024eg asthma / bronchitisAssessmForced Vital Capacity - FVCForced Expiratory Volume in 1 sec - FEV1FEV1 80% of FVCis Normalor in words - you should be able to forcibly expire more than 80% of your vital capacity in 1 sec.67Respiration医疗9/9/2024Forced Vital Capacity - FVCForForced Vital Capacity - FVCVolume (litres)Time (sec)Total Lung CapacityResidual VolumeSpirometryForced Expiratory Volume in 1 sec - FEV11 secFEV1 80% of FVCOBSTRUCTIVE lung disease68Respiration医疗9/9/2024Forced Vital Capacity - FVCVol69Respiration医疗9/9/202469Respiration医疗10/2/2022
