Transmural Pressure

Question 1

What is the definition of transmural pressure?

Answer 1

transmural pressure refers to the pressure inside relative to the outside of a compartment

• transmural pressure dictates the final volume of a flexible structure

decrease in transmural pressure- dec in volume
increase in tp - inc in volume

Question 2

How would you describe the relationship between the transmural pressure and the volume of a flexible structure?

Answer 2

the transmural pressure determines the volume of a flexible structure
PTM = Pin - Pout

Question 3

What is the relationship of the pressure inside a balloon to the pressure outside the balloon and the balloon’s elastic recoil forces?

Answer 3

Transmural pressure = pressure inside- pressure outside
PTM = Pin – Pout

Balloon submerged in water

balloon gets smaller bc the transmural pressure went down as the pressure outside the balloon went up

pressure inside is a consequence of elastic recoil forces of balloon and pressure outside the balloon

Question 4

How would you describe the sequence of events for an infinitely flexible tube after the pressure inside the tube drops below the pressure outside the tube?

Answer 4

so the pressure along tube drops to below the pressure outside - tube collapse and flow stops.
what happens now?
Pressure will then equalize to the pressure (P1) that is highest in the tube. under static conditions, pressure will equalize within the tube.
keeps going thru this oscillating cycle of drop in pressure collapse flow stops and oscillates again

Question 5

What is the meaning of critical pressure for a tube (for example, an airway) that is not infinitely flexible (blood vessel) ?

Answer 5

in a tube that is not infinitely flexible, you will get decrease in pressure down tube to point of a closure of a tube 
this point (p4) = closure = Pcrit 
p crit is the transmural pressure at the point of collapse where the airway pressure is equal to P4
when Ptm> Pcrit airway will collapse

Question 6

what is Ohms law?

Answer 6

Change in pressure = Flow x Resistance

Question 7

An infinitely flexible tube with an outside pressure of 100 mmHg is currently collapsed and therefore has no flow through it. The pressure inside the tube must become greater than ____________ mmHg in order to relieve the collapse and resume flow through the tube.

Answer 7

100

Question 8

when pressure outside a compartment is greater than inside you have a negative tranmural pressure. in the lungs, if the pressure thorax> pressure alveolus then what happens to the flow?

Answer 8

if small airway it will collapse, closed airway will lead to pressure equalization under static conditions

alveloli pressure > thorax pressure after oscillaltion which will open up the tube again

Question 9

why are patients with emphysema are more likely to experience airway collapse than patients with healthy lungs?

Answer 9

patients with emphysema are likely to have floppier smaller airways that are prone to collapse when transmural pressure becomes ingreasling negative.
Small airways have weaker elastic support

Question 10

what is it called when air enters into the pleural space surrounding the lungs? and what is used to get the air out of this space?

Answer 10

pneumothorax

catheter for pleur drainage

Question 11

a condition in which the air sacs of the lungs are damaged and enlarged, causing breathlessness
happens to many past smokers

Answer 11

emphysema