Session 3 Flashcards
(23 cards)
What holds the lungs at a larger volume?
The pleural seal
What force does the layer of fluid between the visceral and parietal pleura exert?
Surface tension
If the lungs are disturbed, what will they spring back to?
The resting expiatory level
What is active; breathing in or out?
Breathing in. It uses the diaphragm and intercostal muscles
When is breathing out passive?
When you are breathing out to resting expiratory level
When can the abdomen not move into the abdomen easily?
Pregnancy
Obesity
Corsets
Define compliance
The stretchiness of the lung.
Volume change per unit pressure change
What disease increases compliance?
Emphyseama
What disease decreases compliance?
Fibrosis
What reduces compliance?
Surface tension of the lining fluid in the lungs
How do detergents decrease surface tension?
They disrupt the interactions between surface molecules in the liquid
What is an example of a detergent in the lungs?
Surfactant (Produced by type II alveolar cells)
It helps reduce surface tension when the lungs are deflated, but not when they’re fully inflated so hard for bigger breaths
Define Hysteresis
The energy put into stretching a film of surfactant. It is not all recovered when the film recoiled. The loss is greatest when the tidal volume is maximal
Why is it harder for asthmatic to breath?
Their lungs are usually relatively full, therefore every breath is like a deep breath.
What is the pressure in large bubbles?
Low
What is the pressure in small bubbles?
High
What is Laplace’s law?
Pressure = 2 x surface tension (of fluid) / radius (Bubble)
Why don’t alveoli collapse into each other?
Bigger alveoli have higher surface tension in their walls because surfactant becomes less effective. This means the pressure in the big bubble stays high so that it doesn’t eat the small bubble
What is respiratory distress syndrome?
Babies are born prematurely, therefore they have too little surfactant making the lungs very stiff with a few large alveoli. The breathing and gas exchange is compromised
Where is the highest resistance in the respiratory system?
In the trachea
Where is the lowest resistance in the respiratory system?
In the small airways (Therefore breathing is easy)
When is resistance in the small airways increased?
Forced expiration - The airways are narrowed so resistance is increased and air is trapped in the alveoli
What is Obstructive airway disease?
The small airways are narrowed by disease which causes an increased resistance much earlier in expiration. e.g. asthma
