Respiratory 17 Flashcards
What is Alveolar Surfactant produced by?
Type II alveolar cells
What does Surfactant do?
Lowers the surface tension of the lining fluid so we can breathe without too much effort. Makes the alveoli stable against collapse
How does Surfactant affect lung compliance?
It increases lung compliance
What are the important components of pulmonary surfactant?
- Phospholipids dipalmitoylphosphatidylcholine (DPPC)
- Phosphatidylcholine
- Surfactant apoproteins
- Calcium ions
How does surfactant reduce surface tension?
The hydrophobic tail sits in the alveolar air and the hydrophilic head dips into water breaking the strong attractive forces that occur between the molecules of water at the surface
How is thickness of surfactant affected by surface area?
Thickness of surfactant decreases with increasing surface area
How is surface tension affected with increasing surface tension since surfactant decreases with increasing surface tension in an alveoli?
Surface tension increases with increasing alveolar diameter
What are the two functions of surfactant?
- Reduces surface tension of alveolar fluid
* Stabilizes the alveoli
What do premature infants lack in the lungs?
Surfactant
What does the lack of surfactant in premature infants do?
Decreases compliance and increases work of breathing causing infant respiratory distress
What is the compliance of saline filled lungs?
Saline filled lungs have a very high compliance because there is no surface tension
What is the compliance in premature lungs?
Compliance is very low because there is no surfactant present to counteract the surface tension
