| Describe the anatomical position of the respiratory control centre and its role in regulation of ventilation. | Pneumotaxic centre – controls inspiratory time. Fourth ventricle – protects human brain from trauma via cushioning effect. Apneustic centre – leads to a gradual increase in the firing rate of the inspiratory muscles. Dorsal respiratory group (inspiration) – controls mostly inspiratorymovements and their timing. Ventral respiratory group (expiration and inspiration) – controls voluntary forced exhalation and acts toincrease the force of inspiration. Vagus and glossophraygeal – provides sensation, including taste, to the posterior third of the tongue, and also sensation to the back of the oral cavity and the oropharynx. |
| How does pCO2 and pH influence ventilation? | O2 and H+ directly influence the respiratory centre. Peripheral H+ ions do not readily pass the blood-brain barrier H+ ions are produced when blood CO2 is elevated – CO2 +H20 H2CO3 H++ HCO3- Respiratory activity strongly influenced by fluctuations in CO2. PCO2 increased during periods of exertion or hypoventilation but is rapidly controlled via changes in VA. |
| Describe the effect of altered pO2 on ventilation. | Low PO2exaggerates the VA response to high PCO2 Low pH exaggerates the VA response to high PCO2 |
| How does exercise alter pO2 ventilation? | VD/VT reduced due to an increase in VT during exercise. Total VE reaches 120L/min and up to 200L/min in tall athletes. An increase in VA at the onset of exercise is due to increased VT and respiratory rate. A progressive increase in VA beyond moderate exercise is primarily due to increased respiratory rate. |
