1、Chapter 5 RespirationWhen you can not breath,nothing else matters Slogan of the American Lung Association1Respiration医疗10/15/2022Respiration is the process by which the body takes in and utilizes oxygen(O2)and gets rid of carbon dioxide(CO2).2Respiration医疗10/15/2022An Overview of Key Steps in Respir
2、ation3Respiration医疗10/15/2022Respiration can be divided into four major functional events Ventilation:Movement of air into and out of lungs Gas exchange between air in lungs and blood Transport of oxygen and carbon dioxide in the blood Internal respiration:Gas exchange between the blood and tissues4
3、Respiration医疗10/15/2022Respiratory System Functions Gas exchange:Oxygen enters blood and carbon dioxide leaves Regulation of blood pH:Altered by changing blood carbon dioxide levels Voice production:Movement of air past vocal folds makes sound and speech Olfaction:Smell occurs when airborne molecule
4、s drawn into nasal cavity Protection:Against microorganisms by preventing entry and removing them Metabolism:Synthesize and metabolize different compounds(Nonrespiratory Function of the Lung)5Respiration医疗10/15/2022Section I VENTILATION 62022-10-15 Occurs because the thoracic cavity changes volume I
5、nsipiration uses external intercostals and diaphragm Expiration is passive at rest,but uses internal intercostals and abdominals during severe respiratory load Breathing rate is 10-20 breaths/minute at rest,40-45 at maximum exercise in adultsVentilation7Respiration医疗10/15/2022 Thoracic Walls and Mus
6、cles of Respiration8Respiration医疗10/15/2022Thoracic Volume9Respiration医疗10/15/2022 Pleura10Respiration医疗10/15/2022Pleural fluid produced by pleural membranesActs as lubricantHelps hold parietal and visceral pleural membranes together11Respiration医疗10/15/202212Respiration医疗10/15/2022 13Respiration医疗1
7、0/15/2022114Respiration医疗10/15/2022215Respiration医疗10/15/2022316Respiration医疗10/15/2022417Respiration医疗10/15/2022518Respiration医疗10/15/2022619Respiration医疗10/15/202220Respiration医疗10/15/202221Respiration医疗10/15/2022II Resistance of the Ventilation Elastic Resistance Inelastic Resistance22Respiration
8、医疗10/15/20221.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10/15/2022 The elastic forces can be divided into two parts:
9、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 elastic forces in a normal
10、 lungs.24Respiration医疗10/15/2022 Surface 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10/15/2022Surface Tension Force exerted by fluid in alveoli to resist distension Lungs secrete and absorb fluid,l
11、eaving 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.26Respiration医疗10/15/202227Respiration医疗10/15/2022Surface Tension Law of Laplace:Pres
12、sure in alveoli is directly proportional to surface tension;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10/15/202229Respiration医疗10/15/2022Surfactant(表面活性
13、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.30Respiration医疗10/15/2022Increase AreaDecreaseAreaLow S/unit AreaHigh S/unit Area31Respiration医
14、疗10/15/2022Surfactant prevents alveolar collapse32Respiration医疗10/15/2022Without surfactantVolume-pressure curves of lungs filled with saline and with air(with or without surfactant)33Respiration医疗10/15/2022Physiology Importance of Surfactant Reduce the work of breathing Stabilize alveoli Prevent co
15、llapse and sticking of alveoli Maintain the dryness of the alveoli Prevent the edema of the alveoli34Respiration医疗10/15/2022Compliance Distensibility(Stretchability,Elasticity):Ease with which the lungs can expand.The compliance is inversely proportional to elastic resistance Change in lung volume p
16、er change in transpulmonary pressure.D DV/D DP 100 x more distensible than a balloon.Specific compliance(比顺应性,CL）:the compliance per unit volume CL=pulmonary compliance/residual volume35Respiration医疗10/15/20222.Inelastic ResistanceThe inelastic resistance comprises 1.airway resistance(friction)2.pul
17、monary tissue resistance(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10/15/2022Airway Resistance Airway resistance is the resistance to flow of air in the airways and is
18、 due to:1)internal friction between gas molecules2)2)friction between gas molecules and the walls of the airways37Respiration医疗10/15/2022Types of Air Flow38Respiration医疗10/15/2022Laminar flow is when concentric layers of gas flow parallel to the wall of the tube.The velocity profile obeys Poiseuille
19、s Law39Respiration医疗10/15/2022Poiseuille and Resistance Airway Radius or diameter is KEY.radius by 1/2 resistance by 16 FOLD-think bronchodilator here!40Respiration医疗10/15/2022The gas flow in the larger airways(nose,mouth,glottis,and bronchi)is turbulentGas flow in the smaller airway is laminarBreat
20、h sounds heard with a stethoscope reflect the turbulent airflowLaminar flow is silent41Respiration医疗10/15/2022Airway Resistance Any factor that decreases airway diameter,or increases turbulence will increase airway resistance,eg:Rapid breathing:because air velocity and hence turbulence increases Nar
21、rowing airways as in asthma(哮喘）,parasympathetic stimulation,etc.Emphysema(肺气肿）,which decreases small airway diameter during forced expiration Increase of the density and viscosity of the inspired gas also increase the airway resistance42Respiration医疗10/15/2022Control of Airway Smooth Muscle Neural c
22、ontrol Adrenergic beta receptors causing dilatation Parasympathetic-muscarinic receptors causing constriction NANC nerves(non-adrenergic,non-cholinergic)Inhibitory release VIP and NO bronchodilitation Stimulatory bronchoconstriction,mucous secretion,vascular hyperpermeability,cough,vasodilation “neu
23、rogenic inflammation”43Respiration医疗10/15/2022Control of Airway Smooth Muscle Local factors histamine binds to H1 receptors-constriction histamine binds to H2 receptors-dilation slow reactive substance of anaphylaxis(过敏反应）-constriction-allergic response to pollen Prostaglandins（前列腺速）E series-dilatio
24、n Prostaglandins（前列腺素）F series-constriction 44Respiration医疗10/15/2022Control of Airway Smooth Muscle(cont)Environmental pollutionsmoke,dust,sulfur dioxide,some acidic elements in smog Elicit constriction of airways mediated by:parasympathetic reflex local constrictor responses45Respiration医疗10/15/20
25、22III Assessment of the Pulmonary Ventilation462022-10-15I.Pulmonary Volume and Capacity472022-10-1548Respiration医疗10/15/2022Pulmonary Volumes Tidal volume(潮气量）Volume of air inspired or expired during a normal inspiration or expiration(400 500 ml)Inspiratory reserve volume（补吸气量）Amount of air inspire
26、d 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，RV）Volume of air remaining in respiratory passages and lungs after the most forceful expiration(1
27、500 ml in male and 1000 ml in female)49Respiration医疗10/15/202250Respiration医疗10/15/2022Pulmonary CapacitiesA Capacity is composed of two or more volumes Inspiratory capacity（深吸气量）Tidal volume plus inspiratory reserve volume Functional residual capacity（功能残气量,FRC）Expiratory reserve volume plus the re
28、sidual volume Vital capacity（肺活量,VC）Sum of inspiratory reserve volume,tidal volume,and expiratory reserve volume Total lung capacity（肺总量,TLC）Sum of inspiratory and expiratory reserve volumes plus the tidal volume and residual volume51Respiration医疗10/15/202252Respiration医疗10/15/2022RV/TLC Normally le
29、ss than 0.25 Increase by the obstructive pulmonary disease(RV)Increase during the restrictive lung disease(TLC)53Respiration医疗10/15/2022Minute and Alveolar Ventilation Minute ventilation:Total amount of air moved into and out of respiratory system per minute Respiratory rate or frequency:Number of b
30、reaths taken per minute Anatomic dead space:Part of respiratory system where gas exchange does not take place Alveolar ventilation:How much air per minute enters the parts of the respiratory system in which gas exchange takes place54Respiration医疗10/15/2022Dead Space Area where gas exchange cannot oc
31、cur Includes most of airway volume Anatomical dead space(=150 ml)Airways Physiological dead space=anatomical+non functional alveoli55Respiration医疗10/15/202256Respiration医疗10/15/202257Respiration医疗10/15/2022II.Measurement of Expiratory Flow-FVC582022-10-15FVC-forced vital capacity(cont)Defines maximu
32、m volume of exchangeable air in lung(vital capacity)forced expiratory breathing maneuver requires muscular effort and some patient training Initial(healthy)FVC values approx 4 liters slowly diminishes with normal aging59Respiration医疗10/15/2022Significantly reduced FVC suggests damage to lung tissuer
33、estrictive 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10/15/2022FEV1-forced expiratory volume(1 se
34、cond)Defines maximum air flow rate out of lung in initial 1 second interval forced expiratory breathing maneuver requires muscular effort and some patient training FEV1/FVC ratio normal FEV1 about 3 liters FEV1 needs to be normalized to individuals vital capacity(FVC)typical normal FEV1/FVC ratio=3
35、liters/4 liters=0.7561Respiration医疗10/15/2022Standard 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/FVC suggests obstructive damage to lung airwaysepisodic,reversible by bron
36、chodilator 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10/15/2022Volume(litres)Time(sec)Forced Vital Capacity-FVCTotal Lung CapacityResidual VolumeSpirometryFor
37、ced Expiratory Volume in 1 sec-FEV11 sec63Respiration医疗10/15/2022eg fibrosis/pulmonary oedema3.Assessment of RESTRICTIVE Lung DiseasesThese are diseases that reduce the effective surface area available for gas exchangeNormal Lung VolumeLung Volume in Restrictive Disease64Respiration医疗10/15/2022REDUC
38、EDVolume(litres)Time(sec)Vital CapacityTotal Lung CapacityResidual VolumeSpirometryRESTRICTIVE lung disease65Respiration医疗10/15/2022eg asthma/bronchitisAssessment of OBSTRUCTIVE Lung DiseasesThese are diseases that reduce the diameter of the airways and increase airway resistance-remember Resistance
39、 increases with 1/radius 4Normal Airway CalibreAirway Calibre in Obstructive Disease66Respiration医疗10/15/2022Forced 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10/15/2022Forced Vital Capacity-FVCVolume(litres)Time(sec)Total Lung CapacityResidual VolumeSpirometryForced Expiratory Volume in 1 sec-FEV11 secFEV1 80%of FVCOBSTRUCTIVE lung disease68Respiration医疗10/15/202269Respiration医疗10/15/2022
