Respiratory Physiology 2.1-Anatomy of Pleural cavity Flashcards
What is the pleural cavity?
a cavity within the thoracic cavity
What is average total volume of lungs?
6L
How full are lungs when breathing normally?
about half full
What is the tidal volume?
how much air you breathe in and out each time
What is functional residual capacity?
amount of air that we normally have left in our lungs at the end of our relaxed expiration
What is inspiratory reserve volume?
extra air that we can breathe in when making big effort to fill up lungs.
Around 3L
What is expiratory reserve volume?
Extra air that we can expire with a bit more effort.
About 1L
What is vital capacity?
maximum amount of air that we can voluntarily expire after a maximum inspiration.
Inspiratory reserve volume plus tidal volume plus expiratory reserve vol.
Diff between capacities and volumes?
capacities- no. different volumes added together
volumes- one volume
How much air is left in lungs after a maximum expiratory effort and what is the name for it ?
Residual volume - 1-1.2 L
Why is residual volume important?
stops the alveoli collapsing
-when the elastic fibres recoil, those elastic fibres don’t cause complete collapse of the alveoli as retain air in them.
If no air, would involve a much greater effort to inflate that alveoli again in inspiration.
Less energy required to inflate the alveoli in the next breath.
provides a volume of air that can allow gas exchange to take place between breaths
-oxygen and carbon dioxide don’t only exchange when we breathe in
Why is expiration passive?
we don’t invest any energy in expiration
When do we invest energy?
in expanding chest wall
invest energy in recruiting muscles to expand the chest wall in inspiration and in doing so stretch elastic fibres
Give characteristics of dead space?
dead space volume is 150 ml
air sitting in those airways unable to participate in gas exchange
What is the hilum of the lungs?
the point at which the lungs connect with the major airways
Describe the pleural cavity?
thin cavity around the lungs
incredibly important in lung function
fluid filled cavity, around 3mls in each cavity
containing pleural fluid
What aspects does the pleural cavity have?
visceral and parietal aspect
a.k.a parietal pleural membrane and visceral pleural membrane
Where is the parietal pleural membrane?
part of pleural membrane that is closest to the ribs and superior surface of diaphragm
Where is the visceral pleural membrane?
attached to the outer surface of the lungs
What does the pleural fluid sitting in the pleural space mean?
the cohesive forces of that fluid ensure that the parietal pleural membrane and the visceral pleural membrane remain in contact with each other.
And allows them to glide across each other but not separate.
Why is the fact the pleural membranes can glide across each other important?
Cohesive force ensures that the lungs are effectively stuck to the ribcage and the diaphragm. because everytime you breathe in your lungs have to glide across the surface of the ribs and the diaphragm.
Your rib cage moves and the lungs have to glide across the rib cage as those two movements occur.
Creates a friction free movement of the lungs.
Make sure the lungs are always stuck to the rib cage so if the rib cage expands, the lungs expand.
Id diaphragm contracts then the lungs follow the diaphragm as well.
What is pleurisy?
inflammation of the pleural membranes stops that smooth gliding of the two pleural membranes across each other
What happens to chest wall during inspiration?
expansion of lungs
What happens to chest wall during expiration?
recoil of chest wall
What stops the lungs wanting to recoil further and the chest wall wanting to expand further?
cohesive force of the pleural fluid that is holding the lungs against the chest wall
What is pneumothorax?
lung recoils away from chest wall and collapses to unstretched size as pleural cavity is opened for e.g. by penetrating wounds.
