Exam 2 - Lecture 4 Flashcards
PAO2 is what in a perfectly healthy adult DIRECTLY after gas exchange?
104 mmHg
After gas exchange occurs, the now oxygen rich blood is considered to be pulmonary ______ blood.
Venous – Because it is returning to the heart
The PAO2 blood becomes pulmonary venous blood, and mixes with what?
bronchiolar admixture blood, which is the pulmonary circulation blood for the tissues in the lungs, and by the time it mixes, it will become 100 mmHg of O2 when it reaches the left atrium
What % of cardiac output is bronchiolar admixture blood?
1%
When does PAO2 become PaO2
When it gets mixed with bronchiolar admixture and becomes 100mmHg
Whats a normal PaO2 for a healthy 20 year old? What is it for a 90 year old?
100mmHg; 80 mmHg
Drops as you age
things go downhill for your lungs after ___ years old and then the rest of your body goes downhill at ____ years old
20;40
What happens to O2 and CO2 if you increase ventilation without increasing blood flow?
Higher O2, Lower CO2
How much dead space for a normal 500mL breath? what portion of the breath becomes deadspace?
150mL, THE LAST PORTION of an inspired breath is the deadspace.
When you inhale 500mL, the 350mL that is actually used for gas exchange gets mixed with
3L of air thats already in the lungs, gets diluted out.
Two types of deadspace are
Anatomical and alveolar
What is anatomical deadspace?
Conducting zones of upper respiratory system
What is alveolar dead space?
alveolar that isnt perfused with blood flow, but is being ventilated.
e.g. pulmonary embolism blocking blood flow from perfusing that portion of the lung.
Which deadspace increases as we age and why?
alveolar
As we lose good alveoli, the others have to work extra hard, which can lead to more dead space. think of the kidney cells with GFR
What is physiological dead space?
Both dead spaces put together!!!!! anatomical + alveolar
VT = ?
this is the equation for tidal volume while accounting for deadspace
VT = VD + VA
E.g. 500 = 150 + 350
VT = VD + VA
What does the D stand for? A?
D = physiological dead space
A = GOOD alveolar ventilation. Bad alveolar ventilation would go under D!!!
VA with a dot above the V means
minute ventilation in alveoli
Whats the equation for alveolar MINUTE VENTILATION?
VA = VT -VD
since its minute, we need to use normal volumes and times them by 12 for each one.
Normal alveolar ventilation per minute is?
4200mL/min
What does VE mean?
Minute total ventilation.
the book will leave the dot above the V off, but it still means minute!
The first 150mL’s we expire will be
deadspace gas, has not been mixed.
O2 = 150mmHg and CO2 = 0mmHg
If we have higher than normal alveolar ventilation, what happens to PAO2 and PACO2
increases PAO2, decreases PACO2
Pulmonary capillary hydrostatic pressure is
7mmHg, favors filtration