Lung Volumes and Ventilation Flashcards
What 3 processes have to happen in order to move O2 out of the lungs?
Ventilation, Diffusion, Blood flow
What is Vd in the lungs?
This is the dead space where there is no gas exchange. Also called conducting zone
What is tidal volume?
This is air that is brought in from inspiration
In some species, the alveolar ventilation is equal to what?
Pulmonary blood flow
What is the RBC transit time at rest?
0.84s
What is the RBC transit time during exercise?
0.28s
Why does RBC transit time decrease so much?
Your cardiac output increases significantly whil the capillary blood volume does not rise enough to make a difference
What is the functional residual capacity of the lungs?
Volume in the lungs with no muscular forces
What is Total Lung Capacity (TLC)?
Maximal inhalation
What is residual volume (RV)?
Amount of air after maximum exhalation. Never able to reach zero
Why do you not want the lungs to have no air in them?
This causes alveolar collapse and makes it hard to reopen in order for inspiration
Why does rapid shallow breathing not increase the volume of air in the alveoli?
It wastes to much of the air in the dead space because air is not going all the way down in the lungs to the major respiratory zones
Why is ventilation greater at the base of the lungs?
Gravity
How do you measure RBC transit time?
Pul. cap. blood volume / Q
How do you calculate tidal volume?
Vt= Vd + Va
How do you calculate the expired ventilation?
Vt x f= (Vd x f) + (Va x f)
What does the ratio between Vd/ Vt tell us?
Help us to determine how much of the air is being ventilated to the alveoli. Vt increases with exercise so it lowers the ratio
What is anatomical dead space
Non gas exchanging volume from the conducting zone
What is physiological dead space?
Mismatch of ventilation and blood flow
What is Bohrs equation?
Vd/Vt= (PaCO2 - PeCO2)/PaCO2
What does Bohr’s equation show us?
Shows that if you increase Vd/ Vt you are going to decrease the pressure of expired air. This is because you are not breathing deep enough and you increase the amount of dead space you have.
How do you calculate alveolar ventilation and why is it important?
Va= (VCO2/PaCO2) x k. Shows that the alveolar ventilation is going to increase with the VCO2 to maintain a pH near 7.4
