Respiratory Mechanics Flashcards
What are the 4 lung capacities?
FRC- functional residual capacity
IC- inspiratory capacity
VC- vital capacity
TLC- total lung capacity
What is FRC?
The volume of air left over in the lungs at the end of passive expiration
What is IC?
Total volume able to be inhaled (TV+IRV)
What is VC?
Total amount of air able to be exhaled after maximum inhalation
What is TLC?
The total volume in the lungs at maximal inflation
What is intrapleural pressure?
Pressure within the pleural cavity
What is alveolar collapse called?
Atelectasis
What muscles life the first two ribs?
Scalene
What muscles lift the sternum outward?
Sternocleidomastoid
What is quiet expiration done by?
Elastic recoil
What muscles cause force expiration?
Abdominal, intercostal, neck and back muscles
What disease are expiration muscles important in?
Increased airway resistance
Why is alveolar pressure negative during the onset of inspiration?
The lungs move with the chest wall outward opening up alveoli causing it to draw air in
What is transpulmonary pressure?
Alveolar pressure-intrapleural pressure
Is it harder to inflate or deflate lungs?
Inflate
Alveoli configuration in negative pressure breathing?
Alveoli closest to the pleural space are larger than internal alveoli
Alveoli configuration in positive pressure breathing?
Innermost alveoli are more expanded than outermost
Is pulmonary fibrosis more or less compliant?
Less compliant; harder to inflate
Is emphysema more or less compliant?
More compliant; harder to deflate
How does obesity affect pulmonary compliance?
Decreases it
What is the basis for most of the lungs elastic recoil?
Surface tension at the air-water interface
Why do smaller airways have less total resistance?
Because they are arranged in parallel
Effects of acetylcholine?
Act on M3 bronchial SM constriction and increase Raw
As lungs empty what happens to Raw?
It increases due to smaller pathways
What happens to Raw as respiratory frequency increases?
It increases
What is PEF?
Peak expiratory flow
How are PEF FEV/FVC affected in restrictive diseases?
PEF low
FEV/FVC normal
How are PEF FEV/FVC affected in obstructive diseases?
PEF FEV/FVC low
What is FEV/FVC?
Forced expiratory volume (forced out in 1 second)/Forced vital capacity
What disease is expected to have a lower FEV/FVC ratio?
Obstructive
