Gas Transport in the Airways Flashcards
What is a healthy range for partial pressure of arterial oxygen content at sea level? In Denver?
90 - 100 Torr; 80 - 85 Torr
Oxygen in the blood is not ________.
a gas, it is dissolved
What is Dalton’s law?
P(IO2) = (P[B] – 47 Torr) x F(O2)
What is P(A[O2])?
The partial pressure of oxygen in the alveoli
What is the equation for pressure of oxygen in alveoli?
P(A[O2]) = P(I[O2]) –(PA[CO2]/R)
What is R (in the equation for alveolar oxygen pressure)?
Respiratory exchange ratio; this represents the amount of CO2 produced for O2 consumed; it is always less than one, and it is lower for fats and proteins than carbohydrates
What is average respiratory exchange ratio for a normal diet?
0.8
If you are breathing 100% oxygen, then R = ____.
1, because all of the expended oxygen must be replaced by CO2 (and not N2)
What is ideal arterial CO2 at sea level?
40 Torr
There is near perfect equilibration of ________ CO2 with ________ CO2.
alveolar; arterial
Describe the alveolar ventilation equation.
Pa(CO2) = (V[CO2]) / (V[A]) x k; this equation gives you arterial CO2 concentration from CO2 produced divided by alveolar ventilation
The alveolar ventilation equation also gives you ___________.
Alveolar CO2, which can be plugged into the alveolar oxygen equation
P(IO2) (in words) is __________; in formula is __________.
the partial pressure of inspired oxygen; P(IO2) = atmospheric pressure x percent of oxygen in the air
The barometric pressure in Denver is roughly ___________.
630 Torr
What is the P(IO2) of a person breathing 100% oxygen at sea level?
713 Torr, because P(B) at sea level = 760 Torr
In words, what does the alveolar gas equation solve for?
It tells you the pressure of oxygen in the alveoli if you know the P(IO2) and the P(A[CO2]), which allows you to determine the A-a gradient of oxygen.
At sea level, normal P(A[O2]) is _______.
100 Torr
CO2 diffusion is _________; the rate-limiting step is _________.
fast; ventilation (that is, expelling CO2 from the lungs)
Pa(CO2) = _________.
[(CO2 produced in one minute) / (alveolar ventilation in one minute)] x k; thus, Pa(CO2) is inversely related to alveolar ventilation
What is hyperpnia?
A state of high ventilation with normal Pa(CO2)–such as is found during exercise, when CO2 levels rise
What is hypoventilation?
Low ventilation and high Pa(CO2), such as can be produced by respiratory depression or severe obstructive disease
What is hyperventilation?
High ventilation and low Pa(CO2), such as is found at high altitude or during anxiety attacks
_________ does not vary with altitude.
Water pressure vapor
Alveolar ventilation can be estimated by the following equation: __________.
V(A) = (V[CO2]) / (P[aCO2]) x k
In Denver, the normal P(a[CO2]) is _________, because of increased ventilation secondary to chronic hypoxia.
30 - 40 Torr
