(II) Mechanisms of respiratory control change the depth or rate of respiration ->change CO2 elimination→→[HCO3]/PaCO2→Acd- base balance
（II）Mechanisms of respiratory control change the depth or rate of respiration →change CO2 elimination→ [HCO3 - ]/ PaCO2 →Acid-base balance
1. central chemoreceptor ●PaCO2(N:4mmHg)↑→ ph of Csf↓→ to stimulate central chemoreceptor→☆ the respiratory center→→ Pulmonary ventilation volume↑ Paco2 >60mmHg(8kPa)> Pulmonary ventilation volume↑10 times but, Paco2>80mmHg(10.7kPa)inhibit respiratory center, named as carbon dioxide narcosis
1. central chemoreceptor PaCO2 (N:40mmHg) ↑→ pH of CSF↓ →to stimulate central chemoreceptor →☆ the respiratory center→Pulmonary ventilation volume ↑ PaCO2 >60mmHg (8kPa) → Pulmonary ventilation volume ↑10 times but, PaCO2 >80mmHg (10.7kPa) →inhibit respiratory center，named as carbon dioxide narcosis
central chemoreceptor The central chemoreceptor is sensitive to the change of co2, which is easy to cross the blood-brain barrier It takes time for the h to penetrate across the blood brain barrier into the interstitial fluid of the brain the increase of [Hf] in the brain is relatively slow, so the effect of ht on the central chemoreceptor will be slow
The central chemoreceptor is sensitive to the change of CO2 , which is easy to cross the blood-brain barrier. It takes time for the H+ to penetrate across the blood brain barrier into the interstitial fluid of the brain, the increase of [H+ ] in the brain is relatively slow, so the effect of H+ on the central chemoreceptor will be slow. central chemoreceptor
2. peripheral chemoreceptor ●PaO2↓、pH↓、PaCO2↑→ to stimulate peripheral chemoreceptor -x the respiratory center→ Pulmonary ventilation volume↑ ●PaO2<60mmHg(8kPa)→☆ the respiratory center; but Pao2 <30mmHg inhibit respirator center e Less sensitive than central chemoreceptor
2.peripheral chemoreceptor PaO2 ↓ 、pH ↓ 、PaCO2↑ →to stimulate peripheral chemoreceptor →☆ the respiratory center→ Pulmonary ventilation volume ↑ PaO2 ﹤60mmHg (8kPa) → ☆ the respiratory center； but PaO2 <30mmHg →inhibit respirator center。 Less sensitive than central chemoreceptor
3. Characteristic of respiratory compensation (a) timeliness The respiratory response begins within several minutes The respiratory response often takes 30 minutes for the respiratory compensation. 12 24 hours to get maximal compensation (b) limited compensation
3.Characteristic of respiratory compensation (a) Timeliness. The respiratory response begins within several minutes. The respiratory response often takes 30 minutes for the respiratory compensation. 12~24 hours to get maximal compensation. （b) limited compensation