呼吸系统生理【医学课件】.pdf

呼吸Respiration Respiration Definition-机体与外界环境之间 进行的。2和C5气体交 换过程The process by which organisms exchange oxygen(02)and carbon dioxide(C02)with the environment呼吸过程 Respiratory processAtmosphereCOjCELLULARRESPIRATION 1 外呼吸J External respiration气体在血液中的运输Gas transport in the blood)内呼吸Internal respiration肺通气Pulmonary ventilation Definition-气体经呼吸道进出肺的过程The process of moving air into and out of the lungs肺通气原理Mechanics of pulmonary ventilation Muscles that cause lung expansion and contraction-Diaphragm（膈肌）、External intercostals（肋间外肌）-Abdominal muscles（腹肌）、Internal intercostals（肋间 内肌）Breathing is an active process To inhale-Contraction of external intercostal muscles 一 elevation of ribs&sternum-increased front-to-back dimension of thoracic cavity 一 lowers air pressure in lungs air moves into lungs-Contraction of diaphragm-diaphragm moves downward-increases vertical dimension of thoracic cavity lowers air pressure in lungs-air moves into lungs To exhale-Relaxation of external intercostal muscles&diaphragm return of diaphragm,ribs,&sternum to resting position-restores thoracic cavity to preinspiratory volume 一 increases pressure in lungs-air is exhaledAir OutAmbient air pressure=760 mm Hg=Density of air moleculesExpirationInspire tian1.Contraction of ribs(internal Intercostals)2.Intrathoradc volume decreased3.Intrathoradc pressure rises4.Therefore,air flows out of airway down its pressure gradient1.Elevation of ribs(external Intercostals)2.Intrathoradc volume increased3.Intrathoradc pressure falls4.Therefore,air flows into airway down its pressure gradient呼吸型式Pattern of respiration Abdominal breathing 腹式呼吸 Thoracic breathing 胸式呼吸 Eupnea平静呼吸 Forced breathing 用力呼吸肺内压Intrapulmonary pressureduring Inspirationat Rest Atmospheric pressure 760 mm Hg)Atmospheric pressure(760 mm Hg)Intra-alveolar pressure(758 mm Hg)Intra-alveolar pressure(760 mm Hg)Diaphragm胸膜腔内压Intrapleural pressure Definition-the pressure within pleural cavityThoracic wallLung 一Heart-Intrapleural fluidParietal pleuraVisceral pleuraMeasurement of intrapleural pressuresINTRAPLEURAL PRESSURE Direct method 直接法Indirect method 间接法/PIuraJ pressureEsopnageal balloonPAhMay closed and alrnow stopped at various lung vofumasFormation of intrapleural pressure Fetus lung Air in lungs after deliveryNewborn Pressures involved-Intrapulmonary pressure=Atmospheric pressure(760 mmHg)-Collapsing force of lung(肺回缩力)-Intrapleural pressureThoracic wallParietal-pleuraPiew.cavityVisceral-pleuraAtmospheric pmssurw1皂 Diaphragm-Intrapulmonary pressure Intrapleural pressure=Atmospheric pressure-Collapsing force of lungatmospheric pressure(750 mm Hg)Physiological significance of intrapleural negative pressure（月匈膜腔负庆）Allow expansion of the lungs利于肺的扩张 Facilitate the venous&lymphatic return促进静脉血和淋巴液的回流气胸 Pneumothorax Air escapes from the lungs or leaks through the chest wall and enters the pleural cavityLateral 单侧Bilateral 双侧肺的顺应性 Compliance of the lungs Definition-the extent to which the lungs expand for each unit increase in pressureC=AV/AP(L/cmH2O)Determined by the elastic forces of thelungs(R,肺弹性阻力)C=1/R3Compliance varies within the lung according to the degree of inflation.Poor compliance is seen at low volumes(because of difficulty with initial lung inflation)and at high volumes(because of the limit of chest wall expansion),with best compliance in the mid-expansion range.Elastic forces of the lungs Sources-1/3 Elastic forces of the lung tissue itself 肺组织本身的弹性回缩力-2/3 Elastic forces caused by surface tension（表面张力）of the fluid that lines the inside walls of the alveoliSurface tension Definition-Elastic-like force existing in the surface of a liquid,tending to minimize the area of the surface-Caused by asymmetries in the intermolecular forces between surface moleculesAir於*夕A*夕A W 货A中1诂/长兴”Pierre Simon Laplace(1749-1827)Laplaces law:P=2T/rNo surfactantLaplaces law:P=2T/rthen Pa e im肺容积Pulmonary volumes潮气量 Tidal volume(TV)-Volume of air inspired or expired with each normal b reathNormal value:400500 ml 补吸气量 Inspiratory reserve volume(IRV)-Amount of air that can be inspired above and beyond TVNormal value:15002000 ml 补呼吸量 Expiratory reserve volume(ERV)-Amount of air that can be expired after a tidal expirationNormal value:900-1200 ml残气量 Residual volume(RV)-RV:the volume of air remaining in the lungs at the end of a maximal exhalationNormal value:M 1500 ml,F 1000 mlLung Volumes and Capacities肺容量Pulmonary capacities 深吸气量 Inspiratory capacity=IRV+TV 功能残气量 Functional residual capacity=ERV+RV 肺活量 Vital volume=TV+IRV+ERVNormal value:M 3500 ml5 F 2500 ml Total lung capacityLung Volumes and Capacities用力呼气量 Forced expiratory volume-The maximal volume of air that can be exhaled as fast as possible from the lungs following a maximal inspiration-Normal value:1st sec.(FEV1)-83%2nd sec.(FEV2)-96%3rd sec.(FEV3)-99%Expired volume(L)6otime(s)肺通气量Pulmonary ventilation volume每分通气量 Minute respiratory volume(MRV)-The amount of air inspired(or expired)during one minute-MRV=TVx breaths/min=500 X12=6000 ml肺泡通气量 Alveolar ventilation(VA)-The amount of inspired air that is available for gas exchange each minute-VA=(TV-dead space)x breaths/min=(500-150)X12=4200 ml无效腔 Dead space一解剖无效腔 Anatomical dead spaceVolume in respiratory passageways which can not be exchanged-150ml-月市泡无效腔Alveolar dead spaceAlveoli which cease to function in gas exchangeNormally 0Right primary bronchusTracheaLeft primary bronchus5 effect of Breathing Patterns on Alveolar VentihitiouTIDAL VOLUME(ML BREATH)XFREQUENCY(BREATHS MIN)=MINUTE VENTILATION(ML MIN)ANATOMIC DEAD-SPACE VENTILATION(ML MIN)ALVEOLAR VENTILATION(ML MIN)150406000150 x40=60000500126000150 x12=18004200100066000150X 6=9005100Summary Terms-Intrapleural pressure-Surfactant-Tidal volume-Vital capacity-Alveolar ventilation