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1、,respiration,第五章 呼吸生理,1.外呼吸 肺通气（外界空气与肺泡之间的气体交换过程） 肺换气(肺泡与肺毛细血管之间的气体交换过程）,呼吸的三个基本环节,气体在血液中的运输 3. 内（组织）呼吸 血液与组织、细胞之间的气体交换过程,肺通气和肺换气,6,The goals of respiration are to provide oxygen to the tissues and to remove carbon dioxide. To achieve these goals, respiration can be divided into four major functiona
2、l events:,7,pulmonary ventilation, which means the inflow and outflow of air between the atmosphere and the lung alveoli; (2) diffusion of oxygen and carbon dioxide between the alveoli and the blood;,8,(3) transport of oxygen and carbon dioxide in the blood and body fluids to and from the cells; and
3、 (4) regulation of ventilation and other facets of respiration. This chapter is a discussion of pulmonary ventilation.,第一节 肺通气,一、实现肺通气的结构特点及功能,鼻、咽、喉、 气管直到终末细支气管,上呼吸道,下呼吸道,二、肺通气原理,（一）肺通气的动力 直接动力：肺泡与大气之间的压力差 原动力: 呼吸运动 呼吸肌收缩、舒张所造成的胸 廓的扩大和缩小，称为呼吸运 动。,1呼吸运动 （1）吸气运动： 膈肌收缩时中部下移，增大了胸腔的上下径，肺容积随之增大，产生吸气。 平静呼吸
4、时膈肌收缩造成的通气量 占总通气量的4/5。,当肋间外肌收缩时，增大了胸 腔的前后径和左右径，肺容积 随之 增大, 产生吸气。,（2）呼气运动： 平静呼气时，因膈肌和肋间外 肌 舒张，肺依靠本身的回缩力 量而回位，产生呼气。,用力呼吸： 除上述肌肉外，有更多的吸气 肌与呼气肌 参与呼吸运动。,用力呼吸,吸气（主动） 膈肌和肋间外肌收缩， 胸锁乳突肌、斜角肌也收缩,呼气（主动） 膈肌和肋间外肌舒张， 腹壁肌肉、肋间内肌收缩,平静呼吸,吸气（主动） 膈肌和肋间外肌收缩,呼气（被动） 膈肌和肋间外肌舒张,膈肌舒缩引起的呼吸运动伴以腹壁的起伏，所以称为腹式呼吸（abdominal breathing）
5、。,由肋间肌舒缩使肋骨和胸骨运 动所产生的呼吸运动，称为胸 式呼吸。Thoracic breathing,26,1. Mechanics Of Pulmonary Ventilation 627.4-628.3 A. Muscles That Cause Lung Expansion and Contraction 629.2-630.2,27,The lungs can be expanded and contracted in two ways: by downward and upward movement of the diaphragm to lengthen or shorten
6、the chest cavity and by elevation and depression of the ribs to increase and decrease the antero-posterior diameter of the chest cavity.,28,Normal quiet breathing is accomplished almost entirely by the first of the two methods, that is, by movement of the diaphragm. During inspiration, contraction o
7、f the diaphragm pulls the lower surfaces of the lungs downward.,29,Then, during expiration, the diaphragm simply relaxes, and the elastic recoil of the lungs, chest wall, and abdominal structures compresses the lungs.,30,During heavy breathing, however, extra force is achieved mainly by contraction
8、of the abdominal muscles, which pushes the abdominal contents upward against the bottom of the diaphragm.,31,The second method for expanding the lungs is to raise the rib cage. when the rib cage is elevated, making the antero-posterior thickness of the chest about 20 per cent greater during maximum
9、inspiration than during expiration.,32,Therefore, all the muscles that elevate the chest cage are classified as muscles of inspiration, and the muscles that depress the chest cage are classified as muscles of expiration. The most important muscles that raise the rib cage are the external intercostal
10、s.,33,The muscles that pull the rib cage downward during expiration are (1) the abdominal recti, which have the powerful effect of pulling downward on the lower ribs at the same time that they and the other abdominal muscles compress the abdominal contents upward toward the diaphragm, and (2) the in
11、ternal intercostals.,34,As the external intercostals they contract, they pull ribs forward, and this causes leverage on the ribs to raise them upward, thereby causing inspiration. The internal intercostals function exactly oppositely, functioning as expiratory muscles, because they angle between the
12、 ribs in the opposite direction and cause opposite leverage.,2肺内压 肺内压是指肺泡内的压力。 吸气初，肺内压低于大气压，空气进入肺泡。呼气初，肺内压高于大气压，肺内气体流出。 吸气末和呼气末，肺内压和大气压相等。,36,Alveolar pressure is the pressure of the air inside the lung alveoli. When the glottis声门is open and no air is flowing into or out of the lungs, the pressures
13、in all parts of the respiratory tree, all the way to the alveoli, are equal to atmospheric pressure, which is considered to be the zero reference pressure in the airways that is, 0 centimeters water pressure.,37,To cause inward flow of air into the alveoli during inspiration, the pressure in the alv
14、eoli must fall to a value slightly below atmospheric pressure (below 0).,38,During normal inspiration, alveolar pressure decreases to about -1 centimeter of water. This slight negative pressure is enough to pull 0.5 liter of air into the lungs in the 2 seconds required for normal quiet inspiration.,
15、39,During expiration, opposite changes occur: The alveolar pressure rises to about + 1 centimeter of water, and this forces the 0.5 liter of inspired air out of the lungs during the 2 to 3 seconds of expiration.,3. 胸内压,胸膜腔内的压力称为胸内压。,胸膜腔内压比大气压低，为负压。 平静呼气末胸膜腔内压约为-5- 3mmHg， 吸气末约为-10-5mmHg。,胸内压=大气压-肺回缩力
16、,胸内压= 肺内压-肺弹性回缩力 = 大气压 - 肺弹性回缩力 若以1个大气压为0， 则 胸膜腔内压= 肺弹性回缩力,46,Pleural pressure is the pressure of the fluid in the narrow space between the lung pleura and the chest wall pleura.,47,Pleural pressure is normally a slightly negative pressure. The normal pleural pressure at the beginning of inspiration is about -5 centimeters of water, which is the amount of suction that is required to hold the lungs open to their resting level.,48,Then, during normal inspiration, th
