T4 L1, Lung mechanisms Flashcards
What is meant by compliance?
The lungs stretching
What are the accessory muscles of respiration and what is their function?
Scalene and sternomastoids. They are muscles other than the diaphragm and intercostal muscles involved in labored breathing
What % of change in lung volume is due to the diaphragm?
75%
Describe what happens with the intercostal muscles during inspiration
The internals relax, externals contract
What happens to the intrapleural pressure during inspiration (becomes negative)?
It decreases so that air from the atmosphere can flow down the pressure gradient
What is trans pulmonary pressure?
The difference between the alveolar pressure and the intrapleural pressure in the pleural cavity
What happens to the trans pulmonary pressure when you breathe a little bit and then stop?
I becomes equal and opposite to the elastic recoil pressure of the lung so that the lungs stay inflated
What is the tidal volume?
It the comfortable volume of air in the lungs
What is residual volume?
The volume of air in the lungs even after exhalation
What is the trans pleural pressure when the chest wall is collapsing?
Negative
What is hysteresis?
When the compliance curves for inspiration and exhalation are different. It’s normal
What happens to compliance when someone has interstitial fibrosis?
It decreases
What happens to compliance when someone has emphysema?
It increases (small changes result in big changes in volume)
What is active exhalation?
When expiratory muscles are used (internal intercostals). Only happens during exercise and disease
What is surface tension and what causes it?
It’s the strong cohesion between molecules caused by the fact that molecules on the surface have no atoms above the so they form stronger bonds with those below them
