Lecture 18: O2 and CO2 EXCHANGE Flashcards
What is the formula for respiratory minute volume?
Tidal volume x respiratory rate
What are the units of respiratory minute volume?
L/min
What are the units of tidal volume?
L/breath
What are the units of respiratory rate?
Breaths/min
What is tidal volume also known as?
Breathing strength
What is respiratory rate also known as?
Breathing speed
Can all the respiratory minute volume be used?
No, some of the air never gets to the alveoli and so cannot gas exchange
What is the air which can’t gas exchange called?
Dead space (Vd)
How much is dead space?
About 150mL
What is dead space interpreted as?
About 150mL of each breath just fills upper airways (conducting airways) and is of no use for gas exchange
What is really important?
The amount of air that gets into the alveoli (alveolar ventilation)
What is the formula for alveolar ventilation?
(tidal volume - dead space) x respiratory rate
What are the units of dead space?
L/breath
What is dead space also known as?
Air that can’t be used. It is constant
What does each gas do in a gas mixture (air?
Exert its own own individual pressure, called a partial pressure
What is the pressure of a mixture of gases equal to?
The sum total of the pressures of each individual gas
What is inhaled air?
Dry and as it becomes filled with water vapour and moistened, the partial pressure of nitrogen and oxygen decrease
What is the goal?
To move gas back and forth between the alveoli and the capillaries
Where is inhaled oxygen transported?
Into the capillaries
Where is carbon dioxide transported?
Into the alveoli to be exhaled