Lung volumes and conversions Flashcards
How do you measure lung volume?
By spirometry; evaluates lung function by measuring the forced expired volume in one second (FEV1)
What is tidal volume?
Air moved in and out of lungs per breath during normal breathing
What is reserve volume?
Amount of additional air that can be moved in and out of lungs per breath during heavy breathing
What is vital capacity?
Total amount of air that can be moved in and out during maximal respiratory effort = tidal volume + inspiratory reserve + expiratory reserve
What is residual volume?
Air left in lungs due to properties of pleural sac; cannot be measured using a spirometry
What is the fixed volume of anatomical dead space?
~150ml
What is alveolar dead space?
Areas of lungs where gas exchange can take place but are not properly perfused with blood; e.g. apex of upright lungs
How does gas move during ventilation within dead spaces and alveoli?
x ml air inspired; pushes the 150ml from dead space into alveoli; x-150 ml fresh air reaches alveoli; x ml air leaves body (x-150ml from alveoli, 150ml from dead space); 150ml from alveoli pushed in to dead space
What is minute ventilation?
Amount of blood moved by lungs in one minute
How do you calculate minute ventilation?
Tidal volume* breathing frequency
What is normal minute ventilation, compared to max minute ventilation (e.g. during exercise)?
Normal: 6 l/min; Max: 150 l/min
What happens during hyperpneoa?
Minute ventilation increases in proportion to metabolic rate
What happens during hyperventilation?
Minute ventilation increases more than metabolic rate does
What are three different schemes lung volume is measure by?
ATPS, BTPS, STPD
What is ATPS?
Ambient temperature and pressure, saturated: P(H2O) at ambient temperature
