Regulation of Respiration Prof. K. Sivapalan

Introduction 20132Regulation of Respiration

Median Sagital Section of Brain 20133Regulation of Respiration

Control of Respiratory Muscles 20134Regulation of Respiration

Respiratory Centre Respiratory center is located bilaterally in Medulla and Pons. The dorsal group of cells are mainly expiratory and the ventral cells are bothe expiratory and inspiratory. Cells in pons inhibit medullary inspiratory cells. Respiratory center is located bilaterally in Medulla and Pons. The dorsal group of cells are mainly expiratory and the ventral cells are bothe expiratory and inspiratory. Cells in pons inhibit medullary inspiratory cells Regulation of Respiration

Rhythmic Activity of the Centers 20136Regulation of Respiration

The Hering-Breuer Inflation Reflex 20137Regulation of Respiration

Chemical Control of Respiration 20138Regulation of Respiration

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] Regulation of Respiration

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 Regulation of Respiration

Each body receives its own blood supply through an artery directly from the arterial trunk. The blood flow in each 2-mg carotid body is about 0.04 mL/min, or 2000 mL/100 g of tissue/min compared with a blood flow 54 mL or 420 mL per 100 g/min in the brain and kidneys. The blood flow is well above the need of the bodies: exposed to arterial blood. Type I cells have catecholamines which are released to stimulate the afferents. They increase discharge in response to reduction in PO 2, increase in PCO 2 and reduction of Hydrogen ion. Each body receives its own blood supply through an artery directly from the arterial trunk. The blood flow in each 2-mg carotid body is about 0.04 mL/min, or 2000 mL/100 g of tissue/min compared with a blood flow 54 mL or 420 mL per 100 g/min in the brain and kidneys. The blood flow is well above the need of the bodies: exposed to arterial blood. Type I cells have catecholamines which are released to stimulate the afferents. They increase discharge in response to reduction in PO 2, increase in PCO 2 and reduction of Hydrogen ion. Receptors Regulation of Respiration

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 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 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 Regulation of Respiration

Factors that Affect Respiration Regulation of Respiration