Anatomy of the Pleural Cavity Flashcards
What is the total volume of the lungs on average?
About 6000ml
About what capacity of the lungs do we use when we are breathing?
About the middle of the lungs capacity
How much air is in the lungs at the end of a normal inspiration?
2.8 L of air.
After every inspiration and expiration how much air do we take in and release out?
500ml
What is the tidal volume ?
The volume of air that we breathe in and out at rest.
What lung capacity do we have when we breathe a tidal volume?
When we have a lung capacity that is about half full.
What is the normal volume left at the end of a normal expiration called?
Functional residual capacity.
How much extra air can be taken in if we take a very deep breath?
About 3L
What is the extra air that we can breathe in from a very deep breath called?
Inspiratory reserve volume
How much more extra air can be breathed out?
About 1.1L
What is that extra air that we can breathe out called?
Expiratory reserve volume
What is a vital capacity?
If we breathe in a really deep breath and then push all that air out, this is the vital capacity.
How much is the vital capacity?
4.6L
What is a capacity?
A number of different volumes added together.
What is a residual volume?
It is the air that is left in the lungs after a maximum residual effort
About how much is the residual volume?
About 1.2L
Can we voluntarily expire residual volume?
No
What are the two functions of the residual volume?
It stops the alveoli collapsing, it provides air that can take place in gas exchange during breaths.
Why is it important that the alveoli do not completely collapse?
Because it would require a greater energy to re-inflate the alveoli than if it still had some air in it.
What is the equation for the vital capacity?
tidal volume + inspiratory reserve volume + expiratory reserve volume
What is the equation for the lung capacity?
vital capacity + residual volume
What is the equation for the inspiratory capacity?
tidal volume + inspiratory reserve volume
What is the equation for the functional residual capacity?
Expiratory reserve volume + residual volume
What is the FEV1:FVC?
Fraction of forced vital capacity expired in 1 second.
What bones form the thoracic cavity?
The ribcage
Do the two pleural cavities speak to each other?
No
What is the hilum of the lungs?
It is the point where the lungs connect with the major arteries, veins and nerves or the arteries, veins or nerves are leaving or entering the lungs.
What is the function of the pleural fluid?
Lubricates the pleural surfaces and allows them to slide smoothly over each other during respiration
What surrounds pleural fluids?
Pleural membrane which surround the pleural cavity.
Where does the pleural membrane double back on itself?
The hilum
What are the two aspects of the pleural membrane?
The visceral and parietal membrane.
Where is the parietal membrane located?
It is the closest to the ribs (stuck to the inside of the ribs), also stuck inferiorly to the diaphragm.
Where is the visceral membrane located?
When the parietal membrane double backs on itself, then it is on the superficial side of the lungs and it goes into all of the fissures.
(Next to the organ of the lungs)
What role does the pleural fluid play in making sure that the visceral and parietal membranes are stuck together?
The cohesive forces of the fluid ensure that the parietal membrane and the visceral membrane remain in contact with each other, allowing them to glide across each other. It also makes sure that the lungs are stuck to the ribcage and the diaphragm.
Why do the parietal and visceral membranes have to glide across each other?
Every time you breath your lungs have to glide across the surface of the ribcage and the diaphragm, and the pleural fluid provides that lubrication that creates a friction free movement of the lungs.
What is pleurisy?
The pleural membranes are inflamed, and then every breath, the patient becomes very painful because that inflammation stops that smooth gliding of the two pleural membranes across each other.
How is the pleural fluid important with regards to the lungs?
It stops the lungs recoiling.
Why does the end of a normal expiration feel comfortable?
There is an equilibrium between the the elastic fibres of the lungs wanting to recoil further and the chest wall wanting to expand further.
What happens when air is introduced into the pleural cavity?
It immediately causes the separation of those two pleural membrane and forces apart the cohesive pleural membranes and so there is nothing preventing the lung recoiling and the chest wall expanding.
What causes a pneumothorax?
When air is introduced into the pleural cavity. The lung collapses to unstretched size.
Where does the parietal membrane double back on itself?
The hilium.
How does the pressure of the intrapleural cavity compare to atmospheric pressure?
Subatmospheric
What activates the skeletal muscles?
Alpha motor neurones
Where does the oesophagus and the aorta pass through the thorax?
Between the pleural sacs
What is the maximum volume of air a pair of lungs can hold?
5800ml
What is the volume of air at the start of a normal inspiration?
2300ml
How do you calculate air to alveoli?
Tidal - dead space
What is the main factor that affects areolar ventilation?
The depth of breathing.
What is partial pressure?
The pressure of a gas in a mixture of gases is equivalent to the percentage of that particular gas in the entire mixture multiplied by the pressure of the whole gaseous mixture
What is atmospheric pressure?
760mmHg
How do you calculate the total lung capacity?
The vital capacity plus the residual volume.
