Lecture 9/10: Gas Exchange Flashcards
What is the point of the lungs?
The point of the lungs is to bring ventilation and perfusion together.
Does the anatomic deadspace participate in gas exchange?
No.
What do conducting airways do?
- Humidify the air 2. Conduct air
How can we alter airway resistance?
Bronchoconstrict Bronchodilate.
If resistance is ____, airflow slows down and takes more muscle effort to do.
high
If resistance is ____, airflow is fast and easy.
low
What controls the airway resistance?
Resistance
Directly related to:
- viscosity of whatever
- length of the tube -
Inversely related to:
- Radius of the tube (4)
R= 8nL/r4
Changes in _____ can have the biggest effects on resistance?
Radius of the tube
What controls the dilation and constriction of our bronchioles?
Smooth muscle
Why do we want to change airway resistance?
So that we can send air to alveoli with a good blood supply
What is alveolar ventilation?
The amount of air that reaches the alveoli.
Va= TD-VDS
=tidal volume - volume of the dead space
Minute alveolar ventilation
What is the average?
Amount of air that reaches the alveoli per minute
Va*Frequency
4L/ minute is the average.
What is perfusion (Q)?
Perfusion (Q) is the amount of blood delivered to the tissue/min.
Average is 5L blood/minute.
Alveolar gas exchange depends on what?
J= SA*D* (P1-P2)/distance
Diffusion of gases:
Increases as surface area, diffusion coefficient and pressure gradient increases.
Decreases as the thickness of the wall increases.
Are gas exchange of O2 and CO2 dependent on one another?
No.
They are independent of one another.
In the lungs, does O2 trade places with CO2?
NOOOO.
How much gas is exchanged (J) every minute?
Of O2 and CO2
250 mL of O2 every minute.
200 mL of CO2 every minute.
thus, they are not equal and not dependent on one another in the LUNGS. In the tissue, yes; they are.
What factors the affect the diffusion of gas directly involve the structure of the alveolus?
1. Surface area
2. Distance (thickness of the alveolar wall)
They can be altered due to pathology.
What is surface area referring to?
It corresponds with the number of alveoli in the lungs and the number of “open” pulmonary capillaries.
Pt presents with COPD. What is causing this?
A decrease in surface area of the alveoli.