与机械通气相关的呼吸生理知识ppt课件

2019/3/24,1,与机械通气相关的呼吸生理知识,西京医院呼吸内科 李志奎,2019/3/24,2,The Respiratory System,与机械通气有关的呼吸生理知识 2. 肺的防御功能： 3.肺容积划分及通气功能： 4.肺泡气与血液的气体交换 5.呼吸动力学基础 6. 呼吸的调节,1. 呼吸系统解剖,2019/3/24,3,Respiratory tract Nose Pharynx upper respiratory tract Larynx Trachea lower respiratory tract Bronchi Lungs-paired organs of respiration Function: supply the body with oxygen and to get rid of excess carbon dioxide resulting from cell metabolism,呼吸系统解剖,以环状软骨下缘为界气管,2019/3/24,4,The Trachea 气管,Position: extends from the lower border of cricoid cartilage (环状软骨)to the level of sternal angle(胸骨角) (between T4T5 vertebrae) where it divides into right and left principal bronchi Structure features Consists of about 1520 C-shaped incomplete tracheal cartilages for patency connected by smooth muscle and connective Carina of trachea 气管隆突 ridge of cartilage at bifurcation分歧into principal bronchi,2019/3/24,5,Bronchi 支气管,Right principal bronchus 右主支气管 Shorter, wider, and more vertical than the left , is about 2.5cm long, Leaves the extend line of the middle line of trachea at 2530o angle Foreign bodies are therefore more likely to lodge in this bronchus or one of its branches Left principal bronchus 左主支气管 Narrower, longer, and more horizontal than the right is about 5cm long, leaves the extend line of the middle line of trachea at about 4050o angle,2019/3/24,6,Bronchial tree支气管树,Each principal bronchus divides into lobar bronchi (two on the left, three on the right), each of which supplies a lobe of lung. Each lobar bronchus then divided into segmental bronchi, which supply specific segments of the lung.,2019/3/24,9,段支气管继之分为小支气管、细支气管、终末细支气管等。 最终与具有呼吸功能的呼吸性细支气管、肺泡管、肺泡囊及肺泡相连。,2019/3/24,10,小气道的概念及其特点,直径2mm 相当于第7级以下的小支气管及细支气管 其最小管径可达0.65mm,小气道的概念,2019/3/24,11,小气道的概念及其特点,管壁菲薄，炎症易波及气道全层及周围组织 无软骨支持，在脱离纤维鞘嵌入肺组织后，管腔通畅性不象软骨性气道，易于受胸腔的压力变化的影响 支气管树的分布特点，决定了分级越高，管径越细。易阻塞 总截面积却大大增加，气流速度慢，以层流为主，其阻力占气道总阻力的20%，难用测总阻力法发现。随着小支气管的7级分支成2050根时，总截面面积上升到19.6cm2，约为气管的8倍。此后，又反复分成6万余根终末细支气管时，总面积达到了180cm2，是气管总截面面积的72倍。 平滑肌相对丰富，改变小气道口径，控制气体流量，调节通气、血流比。 检查方法：流速容积曲线测定 ，闭合气量测定,小气道的特点,2019/3/24,12,支气管上皮细胞,分布于整个气道 长20um，宽7um，基底部2um 每个细胞有纤毛300余根 纤毛长7um，每秒钟向前摆动1000-1500次，可推动粘液层向上运动。 纤毛对外界敏感,纤毛柱状上皮细胞,2019/3/24,13,支气管上皮细胞,夹杂在纤毛柱状上皮细胞之间 其数目随支气管分级增加而减少 平均1mm2面积有6800个粘液细胞 粘液细胞包括杯状细胞及小粘液颗粒细胞 二种细胞可互相转换。,粘液细胞,2019/3/24,14,纤毛细胞,杯状细胞,goblet cell,ciliated cell,2019/3/24,15,支气管上皮细胞,基底细胞为锥形或多角形 位于上皮基膜上，与附近细胞以桥粒相连 基底细胞分化能力强，可分裂自身、纤毛柱状上皮细胞及粘液细胞,基底细胞,2019/3/24,16,支气管上皮细胞,又称嗜银细胞 存在于各级支气管 K细胞分泌5-羟色胺、儿茶酚胺等，参与循环及支气管平滑肌张力的调节。 本身是化学感受器,K细胞,2019/3/24,17,支气管上皮细胞,呈柱状或立方状 分布细支气管以下 能合成、分泌蛋白质，与型肺泡细胞分泌的脂质共同组成表面活性物质，维持末梢气道及肺泡口径的稳定性,Clara细胞,2019/3/24,18,支气管上皮细胞,由15-20个细胞组成，呈菱形或卵圆形 高15um，宽20-40um 分布气道到肺泡，以细支气管分叉处最多 细胞内含有5-羟色胺等物质 可能受中枢调节，具有内分泌功能的神经感受器,神经上皮小体,2019/3/24,19,The Lungs 肺,Position: located in the thoracic cavity by both sides of mediastinum General features Cone-shaped(圆锥), the right lung is shorter and broader, the left one is longer and narrower Apex of lung(肺尖)rises 2 3 cm above the medial third of clavicle into neck Baseconcave(凹面), related to diaphragm(横隔膜), also called diaphragmatic surface Costal surface(肋面)large, convex(凸起的), related to thoracic wall,2019/3/24,20,Medial surface(纵隔面)concave(凹面), related to mediastinum and vertebrae Hilum of lung 肺门：area on medial surface where structures in root enter or leave lung Root of lung 肺根 Contents Principal bronchus Pulmonary artery and vein Nerves and lymphatics Surrounded by connective tissue,2019/3/24,21,Borders Posteriorblunt Inferior sharp Anteriorsharp cardiac notch心切迹 lingual in left lung 左肺小舌 Lobes and Fissure Right lung Two fissures(裂) : horizontal an oblique(倾斜的) Three lobes : superior, middle, inferior Left lung One fissure : oblique Two lobes : superior and inferior,2019/3/24,22,呼吸系统解剖-终末呼吸单位,为终末细支气管以下的单位 是进行气体交换的唯一场所 包括2个呼吸性细支气管 每根再分级3次，最后形成肺泡管、肺泡囊和肺泡 肺泡管由平滑肌-弹力纤维网络组成,终末呼吸单位,2019/3/24,23,肺泡与肺血,2019/3/24,24,呼吸系统解剖-肺泡,平均内径200-250um 内面衬有肺泡上皮细胞 壁内有丰富的毛细血管网及网状纤维、弹力纤维和胶原纤维，网眼内有巨噬细胞、成纤维细胞及肥大细胞 总数：2-6亿之间 面积：40-120m2(size of a tennis court) 有1-2个肺泡孔与相邻肺泡相沟通,肺泡-多面型薄壁囊泡,2019/3/24,25,呼吸系统解剖-肺泡,覆盖肺泡表面95% 表面扁平，为血-气屏障的主要成分。 型肺泡上皮间的连接为绝对不可渗型，防止间质中蛋白或液体流出、防止肺泡腔内流体流入间质 易受损伤，如ARDS 已分化完整，不能再生,型肺泡上皮细胞,2019/3/24,26,呼吸系统解剖-肺泡,覆盖肺泡表面5% 大致圆形，体积小，但数目多，是型的1.7倍。 型肺泡上皮为型的后备细胞 型在分化过程中，其胞浆较正常者为厚，降低了弥散,型肺泡上皮细胞,2019/3/24,27,表面活性物质 (surfactant),肺泡型细胞分泌的二棕榈酰卵磷脂(DPPC),2019/3/24,28,secrete surfactant 增生修复I型细胞,肺泡上皮:,2019/3/24,29,The Pleura 胸膜,General features Serous membranes forming closed sacs Two layers Visceral(内脏的) pleuraadheres to lung, continuous with parietal pleura at root of lung Parietal(体壁的) pleuralines the thoracic cavity,2019/3/24,30,Two pleural layers continue with each other at root of lung forming closed potential spacepleural cavity 胸膜腔 Contains a small amount pleural fluid Subatmospheric pressure in it,2019/3/24,31,Named parts of parietal pleura,Cupula of pleura 胸膜顶 extends up into the neck, over the apex of lung, 23cm above the medial third of clavicle Costal pleura 肋胸膜 lines the inner surface of the wall of the chest Mediastinal pleura 纵隔胸膜 Lines mediastinum Pulmonary ligament 肺韧带 Diaphragmatic pleura 膈胸膜 Lines diaphragm,2019/3/24,32,Costodiaphragmatic recesse肋膈隐窝are the slit-like intervals between costal and diaphragmatic pleurae on each side, the lowest point of pleural cavity Costomediastinal recess 肋纵隔隐窝on the left side between the mediastinal pleural and costal pleura,Pleura recesses 胸膜隐窝potential spaces of pleural cavity which lungs are not occupied in quiet respiration,2019/3/24,33,The Respiratory System,与机械通气有关的呼吸生理知识 1. 呼吸系统解剖 3.肺容积划分及通气功能： 4.肺泡气与血液的气体交换 5.呼吸动力学基础 6. 呼吸的调节,2. 肺的防御功能：,2019/3/24,34,肺的防御功能,传导作用：自鼻到终末细支气管 加温、加湿功能：喉以上为上呼吸道可调节 当到达肺泡时，都接近体温，相对湿度100% 静息时呼出气消耗250ml水分/天 吸入干澡、寒冷的气体可致呼吸道脱水、纤毛功能减退。 经口咽呼吸与经鼻咽呼吸：调节差异不大 经不经上呼吸道呼吸：差别大，须加温、加湿。,吸入气体调节功能,2019/3/24,35,肺的防御功能,成人每天吸入10000-1200L空气 每L空气含数百分悬浮颗粒 滤过作用：10um 2-10um：多在气道、支气管、细支管壁上 0.3-2um：可达终末呼吸单位 0.3um 像水蒸气，可呼出 呼吸性细支气管以下不含纤毛,过滤及清洁机制,2019/3/24,36,肺的防御功能,咳嗽是一高度协调的复杂动作 咳嗽时截面积减少到原来的16% 气体可以85%的速度冲击 咳嗽对气道分泌物多者尤其重要。,咳嗽,2019/3/24,37,The Respiratory System,与机械通气有关的呼吸生理知识 1. 呼吸系统解剖 2. 肺的防御功能： 4.肺泡气与血液的气体交换 5.呼吸动力学基础 6. 呼吸的调节,3.肺容积划分及通气功能：,2019/3/24,38,Pulmonary Function Testing The Basics of Interpretation,Provide quantifiable, reproducible measurement of lung function,2019/3/24,39,Objectives,Identify the components of PFTs Describe the indications Develop a stepwise approach to interpretation Recognize common patterns,2019/3/24,40,Pulmonary Function Testing,Which of the following is used to follow disease severity in COPD patients? Total lung capacity (TLC) Degree of responsiveness to bronchodilators Forced vital capacity (FVC) Forced expiratory volume in 1 second e. Diffusing capacity (DLCO),2019/3/24,41,Description,Spirometry Flow Volume Loop Bronchodilator response Lung volumes Diffusion capacity (DLCO) Bronchoprovocation testing Maximum respiratory pressures Simple and complex cardiopulmonary exercise testing,2019/3/24,42,Indications Diagnosis,Evaluation of signs and symptoms - exertional dyspnea, chronic cough Screening at-risk populations Evaluation of occupational symptoms Monitoring pulmonary drug toxicity Abnormal study - CXR, EKG, ABG, hemoglobin Preoperative assessment,2019/3/24,43,Indications Prognostic,Assess severity Follow response to therapy Determine further treatment goals Referral for surgery Disability,2019/3/24,44,肺通气功能的指标,基本: 肺容积 肺容量,2019/3/24,45,肺容积 (pulmonary volume) 肺容量 (pulmonary capacity),1 潮气量 (TV) 1 深吸气量 (IC) 2 补吸气量 (IRV) 2 肺活量 (VC), 用力肺活量(FVC) 3 补呼气量 (ERV) 3 用力呼气量 (FEV, 时间肺活量) 4 余气量 (RV) 4 功能余气量 (FRC) 5 肺总量 (TLC),2019/3/24,46,Spirometry,Simple, office-based Measures flow, volumes Volume vs. Time Can determine: - Forced expiratory volume in one second (FEV1) - Forced vital capacity (FVC) - FEV1/FVC - Forced expiratory flow 25%-75% (FEF25-75),2019/3/24,47,Lung Volumes,2019/3/24,48,Spirometry,2019/3/24,49,Normal Spirometry,2019/3/24,50,Lung Volumes,IRV,TV,ERV,4 Volumes 4 Capacities Sum of 2 or more lung volumes,RV,IC,FRC,VC,TLC,RV,2019/3/24,51,Tidal Volume (TV),IRV,TV,ERV,RV,IC,FRC,VC,TLC,RV,Volume of air inspired and expired during normal quiet breathing,2019/3/24,52,Inspiratory Reserve Volume (IRV),IRV,TV,ERV,The maximum amount of air that can be inhaled after a normal tidal volume inspiration,RV,IC,FRC,VC,TLC,RV,2019/3/24,53,Expiratory Reserve Volume (ERV),IRV,TV,ERV,Maximum amount of air that can be exhaled from the resting expiratory level,RV,IC,FRC,VC,TLC,RV,2019/3/24,54,Residual Volume (RV),IRV,TV,ERV,Volume of air remaining in the lungs at the end of maximum expiration,RV,IC,FRC,VC,TLC,RV,2019/3/24,55,Vital Capacity (VC),IRV,TV,ERV,Volume of air that can be exhaled from the lungs after a maximum inspiration FVC: when VC exhaled forcefully SVC: when VC is exhaled slowly VC = IRV + TV + ERV,RV,IC,FRC,VC,TLC,RV,2019/3/24,56,Inspiratory Capacity (IC),IRV,TV,ERV,Maximum amount of air that can be inhaled from the end of a tidal volume IC = IRV + TV,RV,IC,FRC,VC,TLC,RV,2019/3/24,57,Functional Residual Capacity (FRC),IRV,TV,ERV,Volume of air remaining in the lungs at the end of a TV expiration The elastic force of the chest wall is exactly balanced by the elastic force of the lungs FRC = ERV + RV,RV,IC,FRC,VC,TLC,RV,2019/3/24,58,Total Lung Capacity (TLC),IRV,TV,ERV,Volume of air in the lungs after a maximum inspiration TLC = IRV + TV + ERV + RV,RV,IC,FRC,VC,TLC,RV,2019/3/24,59,时间肺活量-反映肺活量及呼吸阻力,最大吸气后以最快速度呼气，第1、2、3秒 末呼出气量占肺活量的百分数。,2019/3/24,60,Obstructive Pattern,Decreased FEV1 Decreased FVC Decreased FEV1/FVC - 70% predicted FEV1 used to follow severity in COPD,FEV1 80% 临界状态 80% 轻度 60% 中度 40% 重度,2019/3/24,61,Obstructive Lung Disease Differential Diagnosis,Asthma COPD - chronic bronchitis - emphysema Bronchiectasis Bronchiolitis Upper airway obstruction,2019/3/24,62,Restrictive Pattern,Decreased FEV1 Decreased FVC FEV1/FVC normal or increased,FVC 80% 正常 80% 轻度 60% 中度 50% 重度,2019/3/24,63,Restrictive Lung Disease Differential Diagnosis,Pleural Parenchymal Chest wall Neuromuscular,2019/3/24,64,Pulmonary Function Testing,Which of the following is used to follow disease severity in COPD patients? Total lung capacity (TLC) Degree of responsiveness to bronchodilators Forced vital capacity (FVC) Forced expiratory volume in 1 second e. Diffusing capacity (DLCO),2019/3/24,65,Pulmonary Function Testing,Which of the following is used to follow disease severity in COPD patients? Total lung capacity (TLC) Degree of responsiveness to bronchodilators Forced vital capacity (FVC) Forced expiratory volume in 1 second e. Diffusing capacity (DLCO),2019/3/24,66,Spirometry Patterns,2019/3/24,67,Bronchodilator Response,Degree to which FEV1 improves with inhaled bronchodilator Documents reversible airflow obstruction Significant response if: - FEV1 increases by 12% and 200ml Request if obstructive pattern on spirometry,2019/3/24,68,Flow Volume Loop,“Spirogram” Measures forced inspiratory and expiratory flow rate Augments spirometry results Indications: evaluation of upper airway obstruction (stridor, unexplained dyspnea),2019/3/24,69,Flow Volume Loop,2019/3/24,70,Upper Airway Obstruction,Variable intrathoracic obstruction Variable extrathoracic obstruction Fixed obstruction,2019/3/24,71,Upper Airway Obstruction,2019/3/24,72,Lung Volumes,Measurement: - helium(氦) - nitrogen washout - body plethsmography Indications: - Diagnose restrictive component - Differentiate chronic bronchitis from emphysema,2019/3/24,73,Lung Volumes Patterns,Obstructive - TLC 120% predicted - RV 120% predicted Restrictive - TLC 80% predicted - RV 80% predicted,2019/3/24,74,(二) 肺通气量 (pulmonary ventilation) 肺泡通气量 (alveolar ventilation) 1. 每分通气量,每分通气量 每分钟进或出肺的气体总量。 最大随意通气量 尽力作深快呼吸时，每分钟 所能吸入或呼出的最大气量。 通气贮量百分比=（最大通气量-每分平静通气量）/最大通气量l00,2019/3/24,75,2. 无效腔 肺泡通气量,解剖无效腔,500,2019/3/24,76,解剖无效腔: 不能与血液进行气体交换的呼吸道的容积。 肺泡无效腔: 未能与血液进行气体交换的肺泡容量。 生理无效腔 = 解剖无效腔+肺泡无效腔 肺泡通气量: 每分钟吸入肺泡的新鲜气量, =（潮气量 无效腔气量） 呼吸频率,2019/3/24,77,肺通气量和肺泡通气量,呼吸频率 潮气量 肺通气量 肺泡通气量 (次/min) (ml) (ml/min) (ml/min) 16 500 8000 5600 8 1000 8000 6800 32 250 8000 3200,2019/3/24,78,无效腔与肺泡通气量,每次呼吸使肺泡内气体更新换气1/7 深慢呼吸利于气体交换,2019/3/24,79,The Respiratory System,与机械通气有关的呼吸生理知识 1. 呼吸系统解剖 2. 肺的防御功能： 3.肺容积划分及通气功能： 5.呼吸动力学基础 6. 呼吸的调节,4.肺泡气与血液的气体交换,2019/3/24,80,肺换气: 肺泡与毛细血管之间的气体交换过程。,2019/3/24,81,（二）影响因素,1. 呼吸膜厚度: 反变 肺纤维化、 肺水肿时增厚,2019/3/24,82,呼吸膜面积: 正变 运动时面积增大 肺不张、肺实变、肺Cap 闭塞时面积减小,2019/3/24,83,3 通气/血流比值 0.84 每分肺泡通气量和每分肺血流量的比值。 一般肺泡通气为4L/min，心排出量为5L/min，其比例为0.8 气多或血少 气少或血多 比值升高 比值降低 肺泡无效腔 A-V短路 换气效率低,2019/3/24,84,气/血比值,2019/3/24,85,右向左分流,健康人中有3左右的混合静脉血不经肺毛细血管直接进入体循环的解剖分流。 右至左分流的先天性心血管疾病 肺实变、肺水肿和肺不张等病变 肺毛细血管的混合静脉血，未能与肺进行气体交换而进入肺静脉,2019/3/24,86,右向左分流,若分流量30%，吸高浓度氧亦不易纠正缺氧。 静动脉分流量（Q/QT）可通过单向活瓣吸20分钟纯氧后，抽取动脉血气分析，将所得结果代入Fick公式间接换算而得。 0.0031（PAO2-PaO2） Qs/Qt=- 0.0031（PAO2-PaO2）+（CaO2-CVO2）,2019/3/24,87,Qs/QT代表解剖和肺内右至左的分流之和 PAO2=大气压47PaCO2 CaO2-CvO2为动脉血与混合静脉血氧含量之差值，健康者以5代入，有心肺疾患以3.5代入。 动态随访Qs/QT可了解病情的变化，以及疗效的考核 一般Qs/QT15%可脱离呼吸机（系肺病变所致的分流）。,2019/3/24,88,三、组织换气,血液与组织细胞之间的气体交换过程。,2019/3/24,89,Diffusing Capacity,Diffusing capacity of lungs for CO（DLCO） Measures ability of lungs to transport inhaled gas from alveoli to pulmonary capillaries Depends on: - alveolarcapillary membrane - hemoglobin concentration - cardiac output,2019/3/24,90,弥散(DLCO) 弥散是氧和二氧化碳气体分子通过肺泡毛细血管膜(肺泡膜)的过程 气体分子扩散速度与气体分子在膜两侧的分压差和溶 解度成正比,与气体分子量的平方根成反比 由于二氧化碳的溶解系数远高于氧，其弥散常数为氧的20.7倍，所以临床上不存在二氧化碳弥散障碍，只有氧弥散障碍引起缺氧,2019/3/24,91,Diffusing Capacity,Decreased DLCO (80% predicted) Obstructive lung disease Parenchymal disease Pulmonary vascular disease Anemia贫血,Increased DLCO (120-140% predicted) Asthma (or normal) Pulmonary hemorrhage Polycythemia(红血球增多(症) Left to right shunt,2019/3/24,92,气体在血液中的运输 一、O2、CO2在血中存在的形式,形式：物理溶解、化学结合 气体分压*溶解度 溶解量= 温度,2019/3/24,93,二、O2的运输,形式：物理溶解（1.5%） 化学结合（98.5%）,2019/3/24,94,2019/3/24,95,Hb与O2结合的特征：,反应快、可逆、不需酶催化，主要受 PO2影响 属氧合反应 血红素Fe 2+与珠蛋白组氨酸 结合后，作用点才起作用 1分子Hb可结合4分子O2 氧离曲线呈S形,2019/3/24,96,2019/3/24,97,影响氧解离曲线的因素 1、pH 和pCO2的影响：波尔效应(Bohr) 2、温度 3、2，3-二磷酸甘油酸 （2，3-DPG） 4、其它因素 pH 、 pCO2 或2，3-DPG ： HB 对O2的亲和力，氧解离曲线右移。,2019/3/24,98,Hb氧容量 100ml血的Hb所能结合的最大氧量。 Hb氧含量 100血的Hb实际结合的氧量。 Hb氧饱和度 Hb氧含量和Hb氧容量的百分比。,2019/3/24,99,二、CO2的运输,运输形式：物理溶解（5%） 化学结合 碳酸氢盐 （88%） 氨基甲酸Hb（ 7% ）,2019/3/24,100,CO2化学结合,碳酸氢盐（88%） 氨基甲酸Hb（ 7% ）,2019/3/24,101,The Respiratory System,与机械通气有关的呼吸生理知识 1. 呼吸系统解剖 2. 肺的防御功能： 3.肺容积划分及通气功能： 4.肺泡气与血液的气体交换 6. 呼吸的调节,5.呼吸动力学基础,2019/3/24,102,呼吸 (respiration) 机体与外界环境之间的气体交换过程。,2019/3/24,103,呼吸环节：,1.外呼吸 肺通气+肺换气 2.气体在血中的运输 3.内呼吸 组织换气+细胞内氧化,2019/3/24,104,肺通气 (pulmonary ventilation),肺与外界环境 之间的气体交 换过程。,2019/3/24,105,肺通气原理 肺通气的动力,吸气肌收缩 胸廓扩大 肺扩大 吸气肌舒张 吸气 肺内压大气压 呼气,2019/3/24,106,平静呼吸,2019/3/24,107,2019/3/24,108,（一）呼吸肌,1) 吸气肌 膈肌 肋间外肌,2019/3/24,109,2) 呼气肌 肋间内肌 腹壁肌,2019/3/24,110,3) 辅助呼吸肌 斜角肌 胸锁乳突肌 胸肌 背肌,2019/3/24,111,呼吸过程,平静吸气：主动过程 用力吸气：主动过程 平静呼气：被动过程 用力呼气：主动过程,2019/3/24,112,呼吸的表现形式,用力程度 平静呼吸: 安静时的呼吸 用力呼吸: 加深加快的呼吸 呼吸困难 2) 呼吸肌参与 腹式呼吸: 膈肌活动为主 胸式呼吸: 肋间外肌活动为主 混合式呼吸,2019/3/24,113,（二）与呼吸有关的压力,胸膜腔内压 肺泡内压 气道内压 经胸压 经肺压 经胸壁压 经气道压,2019/3/24,114,肺内压 （肺泡内的压力）,吸气初：肺内压 大气压 呼气开始 呼气末：肺内压 = 大气压 呼气停止,2019/3/24,115,负压人工呼吸 正压人工呼吸,2019/3/24,116,肺内压 胸内压 呼吸气量,2019/3/24,117,胸膜腔内压 (intrapleural pressure)：胸膜腔内的压力,测量：直接法 间接法,2019/3/24,118,胸内压形成,以胸膜腔密闭且含浆液为条件 胸廓生长肺生长 胸廓容积肺容积 胸廓将肺拉大 肺回缩 胸内负压,2019/3/24,119,2019/3/24,120,胸内压=肺内压 - 肺回缩力 =大气压 - 肺回缩力 = - 肺回缩力 呼气末：-3 -5 mmHg 吸气末：-5 -10 mmHg,2019/3/24,121,胸内压作用：,实现肺通气 利于肺换气 利于V血、 组织液回流,2019/3/24,122,（三）肺通气的阻力,2019/3/24,123,1 弹性阻力,弹性阻力：弹性组织对抗外力引起的变 形而产生的回位力。 顺 应 性：弹性组织在外力作用下的可 扩展性。 是指静态条件下，每单位压 力变化而产生的容积变化。 弹性阻力小，容易扩展，顺应性大。,2019/3/24,124,1)肺顺应性曲线,2019/3/24,125,2019/3/24,126,肺充血、肺不张、肺纤维化 肺顺应性 表面活性物质减少 肺顺性 肺气肿 肺顺性,2019/3/24,127,2）比顺应性,=实测肺顺应性/肺总量 顺应性=容积变化/压力变化（L/kPa）,2019/3/24,128,3）肺弹性阻力,产生： 弹性纤维及胶原纤维 （约占1/3） 表面张力（约占2/3） （液气界面）,2019/3/24,129,表面张力的作用：,使液