Chemosensitivity of Medullary Respiratory Neurones
Under normal physiological conditions blood and brain pO2and pCO2are maintained at constant levels by the neural activity that controls breathing. Central respiratory drive is highly sensitive to changes in arterial pCO2, so that even a small increases in pCO2in arterial blood evokes a rapid increase in minute ventilation. Levels of CO2are monitored by the peripheral chemoreceptors located within the carotid bodies, and in some species in the aortic bodies, and by the central chemoreceptors within the medulla oblongata (Daly, 1997; Nattie, 1999, 2001). The ventilatory response to hypercapnia is largely preserved in experimental animals after denervation of the carotid and aortic bodies and according to the estimate of Heeringaet al.(1979) up to 80% of the CO2-evoked response is mediated by the action of CO2at the brainstem chemosensitive sites.
KeywordsReceptor Subunit Nucleus Tractus Solitarii Purinergic Signalling Inspiratory Neurone Expiratory Neurone
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