1、呼吸生理,黃基礎,呼吸的主要作用,細胞與外界之間的氣體交換,氣體交換的方式,單細胞生物：簡單擴散多細胞生物：需要呼吸系統 與循環系統,Five steps for gas exchange,1. Ventilation2. Gas exchange between alveoli and lung capillaries3. Gas transport by circulation4. Gas exchange between tissue cells and tissue capillaries5. O2 consumption and CO2 production,呼吸系統包括：,呼吸道與
2、肺臟,哺乳類的呼吸系統,上呼吸道：鼻腔、咽喉、喉頭肺：氣管、支氣管、小支氣管 、終末小支氣管、呼吸小 支氣管、肺泡道及肺泡,呼吸上皮,Inspiration,側面觀,呼吸體積,潮氣容積吸氣儲備容積呼氣儲備容積肺餘容積肺活量功能肺餘量,以肺量計測定肺換氣體積,Dead space,air that not participate gas exchange between alveoli and lung capillaries,Bird,氣囊,Unidirectional flow,青蛙的呼吸,魚的呼吸,Water versus air breathing (1),Higher viscosit
3、y of water entails higher frictional energy lossHigher density of water causes a higher energy cost in the respiratory cyclelow diffusitivity of O2 in water (need a small diffusion distance for gas transfer)Low solubility of O2 in water,Comparison of physical properties of water and air,Water versus
4、 air breathing (2),Morphological adaptation: the filaments and secondary lamellae providing a large surface area and entailing a very short diffusion distance for gas exchange between water and blood,Water versus air breathing (3),Good physiological performance: a higher arterial partial pressure of
5、 oxygen (PaO2) than that of expired water this is due to the countercurrent arrangement of water and blood which entails the blood in the outflow end from the secondary lamellae has gas exchange contact with inflowing waster,Pulmonary gas transfer in birds versus mammals (1),There are two kinds of a
6、ir filling structures in birds vs the lung in mammals No alveoli in bird but parabronchi from which air capillaries extending to contact with blood capillarieslung volume change during respiratory cycle in mammals vs volume change in air sac in bird,Pulmonary gas transfer in birds versus mammals (2)
7、,Unidirectional airflow in the parabronchi in birds vs a pool of gas in the alveoli in mammals/gas exchange occurs in alveoli in mammals vs in air capillaris in birdcrosscurrent model in bird show a more efficiency of gas exchange comparing with the pool model in mammals higher arterial PO2 than exp
8、ired in bird,Gas Transport in blood,O2 carriage by bloodCO2 carriage by blood,O2 carriage:,1. physical dissolve2. bound to hemoglobin Hb + O2 HbO2 HbO2 + O2 Hb(O2)2 Hb(O2)2 + O2 Hb(O2)3 Hb(O2)3 + O2 Hb(O2)43. oxygen dissociation curve,Factors that modified the O2 dissociation curve,1. CO2 increase (
9、Bohr effect)2. pH decrease 3. temperature increase4. 2,3-DPG increase,shift the curve to the right and favor unloading of O2 from HbO2,O2 dissociation curve,Myoglobin,Hemoglobin,Decrease in pH,Hemo-cyanin display Bohr effect,Root effect,CO2 carriage,1. Physical dissolve2. Carbamino compounds 3. BicarbonateCO2 dissociation curve,Haldane effect,The increase in HbO2 formation in pulmonary capillaries favors unloading of CO2 from bicarbonate and carbamino compound,O2 consumption, CO2 production and tissue gas exchange,Oxygen extraction,
