L7 control of tidal vol and freq Flashcards
what is dead space
places where gas exchange doesnt occur so there’s no alveoli
what increases when the generation of the air increase
branching
what is anatomic dead space
- air used in upper airways that wont be used for gas exchange (in the conducting zones)
- around 150ml
what affects anatomic dead space
- body side
- age (increases)
- head position (decreases if tilted forward)
- drugs (can constrict the airways)
how much of alveolar dead space there is
- aorund 0ml
- because the alveoli are well ventilated and perfused so all the air diffuses out and in
what is physio dead space
-total vol in the RS where no gas exchange is taking place
how to work out physio dead space (
anatomic dead space + alveolar dead space
how does the gas velocity as the air passes through the airways
velocity proportional to 1/CSA
- branching increases from generation 4 so no of airway increases and the diameter of them decreases
- CSA increases so the velocity decreases
formula for air flow
air flow = velocity x CSA
what happens to the velocity of the air from generation 0 to 3
it decreases because the diameter gets smaller but there’s no branching so the CSA decreases
what happens to the velocity of the air from generation 17 onwards
slowed down to the speed of diffusion at the gas exchange
why does the velocity need to be slow in alveoli and capillaries
so the gas exchange can occur efficiently
what is respiratory freq
how fast we are breathing
-f(R)
what is minute ventilation and how to work out it
- vol of air expired per min
- V(T) x f(R)
- not all this ventilation take part in gas exchange
how to work tidal vol (V(T)) regarding dead spaces
V(T) = V(D) + V(A)
tidal vol= dead space + alveolar vol
