Respiratory physiology Flashcards
How is ventilation controlled
Central Chemoreceptors, located in the medulla on the brain side of the BBB and peripheral chemoreceptors
What stimulates Central chemoreceptors
CO2 and H+ions
What stimulates peripheral chemoreceptos
Carotid and aortic bodies by increase in paCO2 , arterial H ions and a decrease in PaO2
what are the afferent neurons of peripheral chemoreceptors
cranial 9 and 10
What is tidal Volume
Amount of air that enters or leaves the lung in a single respiratory cycle at rest(~500ml or 6-8ml/kg
What is inspiratory reserve volume
Additional amount of air that can be inhaled after a normal tidal inspiration
What is Expiratory reserve volume
Additional volume that can be expired after a passive expiration
What is residual volume
amount of air in the lung after a maximal expiration
What is functional residual capacity
Amount of gas in the lungs at the end of a passive expiration
What is inspiratory capacity
maximal volume of gas that can be inspired from FRC
What is vital capacity
maximal volume that can be expired after a maximal inspiration
What is total lung capacity
amount of air in the lung after a maximal inspiration
Why is the FRC so important in Anaesthesia ?
The FRC is of great importance to the anaesthetist because with preoxygenation, the FRC is denitrogenated
Why is preoxygenation important ?
It acts as an O2 reservoir at times of apnoea;e.g at induction of general anaesthesia.
What are the physiologically important reasons of FRC?
O2 buffer
-The air within the FRC acts as an O2 buffer during normal breathing.
O2 continuously diffuses from the alveoli to the pulmonary capillaries.
-Prevention of alveolar collapse
If FRC did not exist (i.e. expiration to RV) alveoli would collapse.
Optimal lung compliance
-Conveniently, lung compliance is at its lowest at FRC.
Pulmonary vascular resistance (PVR) is also at its lowest
