Gas Exchange Flashcards
What does surfactant do?
Reduces the surface tension by reducing the attraction of water molecules for one another
What are the 4 surfactant proteins?
SP-A, SP-B, SP-C, SP-D
What is surfactant made up of?
A phospholipid named dipalmitoyl phosphatidylcholine (DPPC) and 4 surfactant proteins
What is the function of SP-A?
regulate DPPC secretion and function
What is the function of SP-B?
adjusting surface tension (surface tension reduction)
What is the function of SP-C?
adjusting surface tension, similar to SP-B (surface tension reduction)
What is the function of SP-D?
regulate DPPC secretion and function, similar to SP-A
What is the function of prostaglandins in regards to surfactant?
Promote secretion of the surfactant by Type 2 pneumocytes
What things inhibit secretion of surfactant?
SP-A and DPPC by negative feedback
Changing what factor has the greatest effect on airflow?
Radius
How much O2 crosses the alveolar border every minute?
250 mL
How much CO2 crosses the alveolar border every minute?
200 mL
What does J stand for?
Diffusion rate in ml / min
What two factors in the J equation depend directly on the structure of the alveolus? What does this mean?
surface area and distance. They can be changed by pathology
What condition lowers surface area of the alveoli?
COPD
What 4 things make up the distance between the blood and an alveoli? What is the distance?
1.) Fluid layer 2.) Alveolar epithelium 3.) Interstitial space 4.) Blood vessel wall .6 microns
How long does an RBC spend in a capillary under normal conditions? How long does it require to reach equilibrium?
3/4 of a second. 1/4 of a second.
During exercise, how long may an RBC spend in a capillary? How may this affect someone with lung disease?
.25 seconds, meaning no extra buffer period. People with lung disease will notice this during exercise.
What is the abbreviation for diffusion capacity of the lung for oxygen?
DLo2
What is the DLo2 at rest?
21 ml O2/min/mm Hg
How do you measure DLo2?
Carbon monoxide. Have patient inhale small amount of CO. Then multiple DLco x 1.23
How long does it take for CO2 to reach equilibrium in the capillaries?
Not very long, almost instantaneously
What is the DLco2?
400 ml CO2/min/mm Hg. This is the 20x the DLo2.
Summary Slide
What is interstitial lung disease? What effect does it have on J?
It is the depostition of collagen within interstitial spaces, this increases the diffusion distance and decreases diffusion.
What does D depend on? (2 things)
The solubility of gas in water. The molecular weight of the gas
