Chemosensory pathways in the brainstem controlling cardiorespiratory activity.
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
2603 - 2610.
Cardiorespiratory activity is controlled by a network of neurons located within the lower brainstem. The basic rhythm of breathing is generated by neuronal circuits within the medullary pre-Botzinger complex, modulated by pontine and other inputs from cell groups within the medulla oblongata and then transmitted to bulbospinal pre-motor neurons that relay the respiratory pattern to cranial and spinal motor neurons controlling respiratory muscles. Cardiovascular sympathetic and vagal activities have characteristic discharges that are patterned by respiratory activity. This patterning ensures ventilation-perfusion matching for optimal respiratory gas exchange within the lungs. Peripheral arterial chemoreceptors and central respiratory chemoreceptors are crucial for the maintenance of cardiorespiratory homeostasis. Inputs from these receptors ensure adaptive changes in the respiratory and cardiovascular motor outputs in various environmental and physiological conditions. Many of the connections in the reflex pathway that mediates the peripheral arterial chemoreceptor input have been established. The nucleus tractus solitarii, the ventral respiratory network, pre-sympathetic circuitry and vagal pre-ganglionic neurons at the level of the medulla oblongata are integral components, although supramedullary structures also play a role in patterning autonomic outflows according to behavioural requirements. These medullary structures mediate cardiorespiratory reflexes that are initiated by the carotid and aortic bodies in response to acute changes in PO2, PCO2 and pH in the arterial blood. The level of arterial PCO2 is the primary factor in determining respiratory drive and although there is a significant role of the arterial chemoreceptors, the principal sensor is located either at or in close proximity to the ventral surface of the medulla. The cellular and molecular mechanisms of central chemosensitivity as well as the neural basis for the integration of central and peripheral chemosensory inputs within the medulla remain challenging issues, but ones that have some emerging answers.
|Title:||Chemosensory pathways in the brainstem controlling cardiorespiratory activity|
|Location:||Royal Soc, London, ENGLAND|
|Keywords:||chemosensitivity, hypercapnia, hypoxia, medulla oblongata, sympathetic, vagus, ROSTRAL VENTROLATERAL MEDULLA, RESPIRATORY RHYTHM GENERATION, NUCLEUS-TRACTUS-SOLITARIUS, SYMPATHETIC VASOMOTOR TONE, P2X(2) RECEPTOR SUBUNIT, SYMPATHOEXCITATORY NEURONS, CARDIOVASCULAR REGULATION, CENTRAL CHEMOSENSITIVITY, CENTRAL CHEMORECEPTION, CAROTID-BODY|
|UCL classification:||UCL > School of Life and Medical Sciences > Faculty of Life Sciences > Biosciences (Division of) > Neuroscience, Physiology and Pharmacology|
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