Flashcards in Respiratory Physiology Deck (126)
What is the hamburger shift?
Occurs in the RBC
After conversion of CO2 to carbonic acid/bicarbonate the H+ ions created are buffered by Hb but the HCO3- ions are pumped out of the cell in exchange for Cl- ions
At the alveoli, the whole process is reversed and CO2 is breathed out
What is the shape of the CO2 dissociation curve?
What is the Haldane effect?
Ability of deoxygenated blood to carry more Co2 than oxygenated blood
What does the Henderson-Hasselbach equation relate?
pH, [CO2], [HCO3-] with a constant that is the same for all human beings at 37 degrees
Basically says that pH is a function of the ratio of PCO2 and serum HCO3-
What is ventilation and perfusion?
Ventilation = movement of gases in and out
Perfusion = blood flow through any organ
What is the difference between alveolar vessels and extra alveolar vessels?
Alveolar vessels = capillary beds around alveoli
Extra alveolar vessels = running through lung parenchyma
What is hydrostatic pressure?
The force exerted by weight of fluid due to gravity
What did starlings resistor show?
Had a collapsible segment and showed that for the collapsible segment to stay patent then upstream pressure must be greater than the pressure outside of the collapsible segment
What is the relationship between arterial pressure, alveolar pressure and blood flow through alveolar vessels?
Arterial pressure must be greater than alveolar pressure for blood to flow through alveolar vessels
What affects the arterial pressure in different alveolar vessels?
Hydrostatic pressure which alters at different areas of the lungs determined by their position relative to the right ventricle
What is zone 1 in the lungs in terms of V/Q mismatch?
Alveolar pressure is greater than arterial pressure so capillaries collapse
Good ventilation but no perfusion
What is zone 2 in the lungs in terms of V/Q mismatch?
Arterial pressure is greater than alveolar pressure so perfusion
Recruitment of alveoli in systole
What is zone 3 of the lungs in terms of V/Q mismatch?
Arterial pressure is greater than alveolar pressure so blood flow good
some alveoli may be collapsed
Why might you have expansion of the dead space (zone 1) of the lungs in haemorrhage or positive pressure ventilation?
Drop in arterial pressure - less of recruitment zone perfused
Positive pressure ventilation
Rise in alveolar pressure - so alveolar pressure is greater than arterial pressure and capillaries collapse
What would be the ideal V/Q?
What is the average V/Q and are the values higher or lower in the apical regions and basal regions?
Average = 0.8
Apical regions - higher (as much as 3.3)
Basal regions - lower (as low as 0.6)
What is anatomical dead space?
Conducting airways where no gas exchange could occur
What is alveolar dead space?
Unperfused or poorly perfused alveoli
What is physiological dead space?
Anatomical dead space + alveolar dead space
What happens to alveolar dead space in PE?
What is shunt?
Deoxygenated blood reaching the left side of the heart either by bypassing the heart or failing to be oxygenated in the lungs
How is minute ventilation calculated (VE)?
Breathing frequency x tidal volume
What are the 2 parts of the brain making up the respiratory center in the brain?
The Pons and the Medullar oblongata
What are the 2 parts of the medulla oblongata part of the respiratory center in the brain and what kind of neurones do they contain?
1) Ventral respiratory group - contains a mixture of neurones which fire during inspiration and expiration
2) Dorsal respiratory group - only contains neurones which fire during expiration
What kind of neurones are the neurones in the ventral and dorsal respiratory groups of the medulla oblongata?
Autonomic neurones - they never flat line - without any in puts they still fire
What ensures you dont get inspiratory and expiratory neurones in the medulla oblongata firing at the same time?
Reciprocal control between the ventral respiratory group (mixed) and dorsal respiratory group (only inspiration) so you dont get both inspiratory and expriatory neurones firing at the same time
Why is there very little if any expiratory activity at rest?
Expiration at rest is a passive process
What is the role of the pons part of the respiratory center in the brain?
To control the dorsal respiratory group of the medulla oblongata
What are the 2 parts of the pons part of the respiratory center in the brain an what does each do?
Apneustic center - stimulates inspiratory neurones
Pneumotaxic center - inhibits inspiratory neurones
Both only act on the dorsal respiratory group of the medulla oblongata (only contains inspiratory neurones)