expiration. 2.2 The reflex ofrespirationmuscle propriocepto Significance:when respiration muscle is passively stretched of isometric contract,it can be contracted and strengthened reflexly through respiration muscle propriocepto.It is profitable to overcome the resistance and sustain the normal gas volume ofrespiration. 3 Humoral regulation of respiratory 3.1 peripheral chemoreceptor: Carotid body and aortic body:stimulated when PCO2 in blood increases,PO2 in blood decrease,H+Concentration in blood increase. 3.2 Influence of CO2 to respiration (1 Act indirectly to central chemoreceptor(main pathway) (2)Act directly to peripheral chemoreceptor 3.3 Effect of O2 to respiration The main pathway is acting directly on peripheral chemoreceptor and inputting impulse.respiration center is excited. (1)Hypoxia stimulation act through peripheral chemoreceptor.if the inputing of peripheral chemoreceptor is cut,the stimulation effect disappear. (2)The direct effect of hypoxia to center is light inhibition. (3)Mild hypoxia (PO2>80mmHg)has no obviouseffect to respiration. 3.4 Effect of H+to respiration (1)Increasing H+or decreasing PH can faster respiration.It is the effectiveexpiration. 2.2 The reflex of respiration muscle propriocepto Significance: when respiration muscle is passively stretched of isometric contract, it can be contracted and strengthened reflexly through respiration muscle propriocepto. It is profitable to overcome the resistance and sustain the normal gas volume of respiration. 3 Humoral regulation of respiratory 3.1 peripheral chemoreceptor： Carotid body and aortic body: stimulated when PCO2 in blood increases, PO2 in blood decrease, H+ Concentration in blood increase. 3.2 Influence of CO2 to respiration （1）Act indirectly to central chemoreceptor(main pathway) （2）Act directly to peripheral chemoreceptor 3.3 Effect of O2 to respiration The main pathway is acting directly on peripheral chemoreceptor and inputting impulse.respiration center is excited. (1) Hypoxia stimulation act through peripheral chemoreceptor.if the inputing of peripheral chemoreceptor is cut, the stimulation effect disappear. (2) The direct effect of hypoxia to center is light inhibition. (3) Mild hypoxia （PO2＞80mmHg）has no obvious effect to respiration. 3.4 Effect of H+ to respiration (1) Increasing H+ or decreasing PH can faster respiration. It is the effective