Exam 2 - Lecture 3 Flashcards
The top of the lung has what kind of blood flow?
Pulsatile
Zones 2 and 3 for entirely healthy people will have what kind of blood flow
continuous
How many west zones are there?
4
What is gravity dependence?
Gravity makes blood weigh more, which causes the vessels to open up and become distended.
When someone say an area of the lung is dependent, they’re referring to
the area closest to the planet
When alveoli pressure is 0 cmH2O, this means its relative to pressure ______
outside of the body
What holds the alveoli open?
Intrapleural space being -5cmH2O
Later lecture he said it’s more related to volume???? Lmao whatever
What are our alveoli made out of and what does this do?
elastic tissue, causes recoil pressure.
Recoil is ____ to intrapleural pressure.
opposite
e.g. If alveoli is 0, and intrapleural pressure is -5, then recoil pressure is +5.
If diaphragm contracts and causes intraplueral pressure to become -6cmH2O, what happens to alveolar pressure?
alveoli hasn’t expanded yet, so its pressure is now -1 because the elastic recoil pressure is still only +5.
Once alveoli expands from intrapleural pressure decreasing, the expansion of the tissue does what to recoil pressure?
Increases it.
e.g. intrapleural is now -6, but the recoil pressure has increased because the alveoli are stretched, so its now +6 and alveoli pressure is back to 0, but now filled with air.
When the diaphragm relaxes, and intrapleural pressure is now back to -5, what does this do to alveoli pressure?
Makes it +1, because the recoil pressure is still +6 while it has air in it.
What is the delta P that “empties the lung”?
The pressure in the alveoli vs the pressure outside the body.
What is the equation to figure out alveolar pressure?
PA = PIP + PER
e.g. 0 = -5 + 5
What’s another name for elastic recoil pressure?
Transpulmonary pressure
How can we solve for elastic recoil pressure?
PTP = PA - PIP
What is the force that gets the air into the lung?
Transpulmonary pressure
Sounds counterintuitive, but it’s the pressure that’s available to fill the lung, and this is true regardless of type of ventilation. Yes, even PPV.
If transpulmonary pressure goes up, then what happens to lung volume?
Goes up.
Inverse is true as well.
True/False: Pulmonary vascular resistance mostly stays the same
False
Constantly changing!!
What is the biggest influence on pulmonary resistance? What’s the other one mentioned?
Gravity
Also mentioned lung volume
The more air in the lungs, the higher or lower PVR?
Higher
What other structure can affect PVR? (not blood flow/heart)
Muscles
The lowest possible air we can have in the lungs is
RV
When is PVR the lowest during the respiratory cycle?
In between breaths, FRC.