生理学之呼吸系统.ppt

,Chapter 5,RESPIRATION,Introduction Containing:inspiration&expiration Functions:Obtain O2 from external environment Remove CO2 form the body Respiratory processes:Pulmonary ventilation Gas exchange in the lung Gas transport in the blood Gas exchange in the tissue,Respiratory processes,1.Pulmonary ventilation Definition Principles of pulmonary ventilation*Driving force Direct:pressure changes in alveoli Source:contraction of respiratory muscles Inspiratory muscles:Diaphragm,External intercostal muscle Expiratory muscles:Diaphragm,Ext-&Internal intercostals Accessory respiratory muscles,Respiratory movement,Types of respiration Eupnea&Forced breathing(Deep breathing)Abdominal&Thoracic breathing Principles of pulmonary ventilation Contraction(Relaxation)of inspiratory musclesExpansion(Reduction)of thoracic cavity(?)Distension(Recoil)of alveoli Intrapulmonary pressure()atmo-spheric pressureAir flows into(out of)the alveoli,Intrapulmonary pressure Inspiratory phase:1 atm At the end of inspiration or expiration:=1 atmIntrapleural pressure Concept&Changes during respiratory cycle More negative as inspiratory processing Less negative as expiratory processing Measurement&Expression Direct&Indirect measurement 775 mmHg or 5 mmHg Always 1 atm under static condition,Changes of intrapulmonary&intrapleural pressure during respiratory cycle,FormationIAP&PRF has opposite directions,so IPP=IAPPRF At the end of insp-&expiration,soIPP=ASPPRF If ASP=0,IPP=0PRF=PRF IPP:intrapleural pressure IAP:intra alveolar pressure PRF:pulmonary recoil force ASP:atmospheric pressure,Formation of intrapleural negative pressure,Significance Physiological Distend the lung&Make inspiration easier Promote venous&lymph return in the chest Pathological(Pneumothorax)Collapse the lung&Make inspiration difficult Affect venous&lymph return Fatal in pulmonary&circulatory failure cases Importance Keep the interpleural cavity hermetically sealed,*Resistance to breathing Elastic of the lung Elastic&Compliance CL=1/RL=VL/PL(L/cmH2O)Static compliance(Cst)of the lung S shaped curve,divided into 3 portions Flattened upper portion Steep middle portion Flattened lower portion Special compliance(Csp)Csp=CL/TLC,Static compliance(Cst)of the lung,S shaped compliance curve of the lung,Source of elastic of the lung Elastic tissue(1/3)&Alveolar surface tension(2/3)Pulmonary surfactant Nature:A lipoprotein,Main lip component is DPL Characteristics:Both hydro-philia&-phobicity Source:Type II alveolar epithelial cells Distribution:Inner surface of the alveoli Action:Reduce the alveolar surface tension Significance:Decrease the inspiratory resistance,Stabilize the volume&pressure in the alveoli,Prevent pulmonary edema,Pulmonary compliance curve when filled with air or saline,Pulmonary recoil force in the big&small alveoli communicated each other,Elastic of the thorax Characteristics of elastic resistance of the thorax,Non-elastic resistance Airway resistance(main)Definition&Calculation,Factors affecting the airway resistance:Velocity of air flow:RAW VAF Type of air flow:Laminar flow Chemical factors,Differences between the large&small airway,Pulmonary volume&capacity*Tidal volume(TV)*Inspiratory reserve volume(IRV)*TExpiratory reserve volume(ERV)*Residual volume(RV)*Inspiratory capacity(IC)*Functional residual capacity(FRC)*Vital capacity(VC)*Forced vital capacity(FVC)&Forced expiratory capacity(FEC)*Total lung capacity(TLC),Pulmonary volume&capacity,Forced expiratory volume,Pulmonary ventilation volume*Minute ventilation volume*Maximal(voluntary)ventilation AV=(2TVDSV)RF/2,2.Respiratory gas exchange Mechanisms of gas exchange*Driving force:Partial pressure of O2 or CO2*Mode:Diffusion of gas*Condition:Permeability of membrane Processes of gas exchange Po2&Pco2 in alveoli,blood&tissue(mmHg),Processes of gas exchange,Factors affecting gas exchange*Diffusion rate of gas,*Ventilation/perfusion ratio(V/Q)Definition&its normal value(0.84)If V/Q 0.84:Alveolar dead space V/Q 0.84:Functional A-V shunt Anoxia occurs more easily than CO2 retention Affecting by gravity when a person stands,Respiratory membrane,Ventilation/perfusion ratio(V/Q),3.Gas transport in the blood Oxygen transport*Forms of transport Physically diffusion&Combination with Hb,DN:,*Characteristics of Hb combined with O2 Fast,reversible,need not enzyme,oxygenate with Fe2+,O2 combined with Hb is 4:1,S shaped oxygen dissociation curve*Oxygen capacity,content&saturation*Cyanosis&carbon monoxide poisoning,*Oxygen dissociation curve Definition&why it is in S shaped Physiological advantages of S shaped curve The flattened upper portion(60100 mmHg)The steep middle portion(4060 mmHg)The steep lower portion(1540 mmHg)Factors affecting oxygen dissociation curve Concept of P50,affinity to O2,right or left shift Factors:pH&Pco2(Bohr effect),temperature,2,3-DPG,others(Fe2+Fe3+,CO),Oxygen dissociation curve,Factors affecting oxygen dissociation curve,Carbon dioxide transport*Forms of transport Physically diffusion Combination with Hb HCO3&HHbNHCOOH,*Carbon dioxide dissociation curve*Influence of combination of Hb with O2 on CO2 transport(Haldane effect),Carbon dioxide transport in the blood,Carbon dioxide dissociation curve,4.Regulation of respiratory activity Respiratory centers*In the spinal cord*In the lower brain stem Research techniques:Brain stem transection,Microelectrode,etc.Medullary oblongata:DRG:VL-NTS VRG:cVRG,i(or r)VRG,Bt C,pre-Bt C Pons:Pneumotaxic center,PBKF(NPBM+KF)*In the higher brain:Cerebral cortex,Limbic system,Hypothalamus,Research on respiratory centers:Brain stem transection,Formation of respiratory rhythm*A key region of its generation:Pre-Bt C*Central inspiratory activity generator(CIAG)&Inspiratory off switch mechanism(IOS)Respiratory reflexes*Pulmonary stretch reflex(Hering-Breuer)Inflation&deflation reflex*Chemoreflex Peripheral&central chemoreceptors Respiratory regulation of CO2,H+&O2 Interaction of CO2,H+&O2 on the regulation*Proprioceptive reflex of respiratory muscles,PBKF,CIAG,Insp.Neurons,IOS,Insp.Muscular Neurons,Insp.movement,PSR,+,+,+,+,+,+,+,Insp.center(medulla),Insp.Neurons(spinal cord),Contraction(or relaxation)of insp.muscles,Inflation(or Deflation),Inflation receptor or deflation receptor,Off switch mechanism,+,Paco2H+a Pao2,Carotid&aortic bodies,Resp.Center(Medulla),BBB,CO2+H2O,Central chemoreceptor,Resp.A&F,HCO3H+,CO2,O2,O2,H+,H+,CSF,Blood,(),A:amplitude;F:frequencyBBB:blood-brain barrierCSF:cerebrospinal fluid,Respiratory regulation of CO2,H+&O2,