1. Regulation of Respiration Prof. K. Sivapalan

2. Introduction 20132Regulation of Respiration

3. Control of Respiratory Muscles 20133Regulation of Respiration

4. The Hering-Breuer Inflation Reflex 20134Regulation of Respiration

5. Chemical Control of Respiration 20135Regulation of Respiration

6. Central Chemo-receptors Cells in ventral Medulla respond to changes in Hydrogen ions in CSF which is proportional to PCO 2. Blood pH has no effect as H + is not permeable through Blood brain barrier. The central chemo receptors activate respiratory centre when CO 2 increases and inhibit when it decreases. The effect is potent immediately but after one day the HCO 3 - diffuses into CSF and reduces the effect. [Renal compensation] Cells in ventral Medulla respond to changes in Hydrogen ions in CSF which is proportional to PCO 2. Blood pH has no effect as H + is not permeable through Blood brain barrier. The central chemo receptors activate respiratory centre when CO 2 increases and inhibit when it decreases. The effect is potent immediately but after one day the HCO 3 - diffuses into CSF and reduces the effect. [Renal compensation] 20136 Regulation of Respiration

7. Peripheral Chemo-receptors Most receptors- Carotid bodies near the bifurcation – glossopharingeal nerve. Some receptors in the arch of the aorta- vagus nerve A few receptors in abdominal and thoracic vessels. Most receptors- Carotid bodies near the bifurcation – glossopharingeal nerve. Some receptors in the arch of the aorta- vagus nerve A few receptors in abdominal and thoracic vessels. 20137Regulation of Respiration

8. There is normal discharge at the PO 2 of 100 mm Hg. It decreases as partial pressure increases and increases when partial pressure decreases. The maximal change is between PO 2 of 60-30 mmHg. The response is not affected by duration of hypoxia. Denervation of carotid bodies results abolishes response to changes in – Oxygen tension- totally – pH- great extent – Carbon dioxide by 30% Central for carbondioxide and peripheral for oxygen and hydrogen. There is normal discharge at the PO 2 of 100 mm Hg. It decreases as partial pressure increases and increases when partial pressure decreases. The maximal change is between PO 2 of 60-30 mmHg. The response is not affected by duration of hypoxia. Denervation of carotid bodies results abolishes response to changes in – Oxygen tension- totally – pH- great extent – Carbon dioxide by 30% Central for carbondioxide and peripheral for oxygen and hydrogen. Response to Oxygen 20138Regulation of Respiration

9. Factors that Affect Respiration 20139Regulation of Respiration