5.3 Pulmonary Flashcards
we are designed to have ____ gradients for exchange?
partial pressure
*O2 leaves capillaries into tissue where CO2 leaves tissue, at alveoli it is opposite; all due to PP
Parital pressure gradients are the driving force of?
diffusion at both pulmonary capillaries AND body tissue
average pressure at sea level
760mm of Hg
*O2, CO2, N2 and each other gas in the atmosphere contribute a part of the overall 760 mm Hg total barometric pressure
so what IS partial pressure?
the pressure contibution of a gas to overall totoal pressure
*doesn’t matter which gas you are talking about! diffusion is by partial pressure
1) what is another way of saying partial pressure?
2) of mm Hg?
1) tension
2) torr
units for
1) cardio
2) ventilation mechanics
3) gas exchange
1) mm Hg
2) cm of H2O
3) mm Hg
what is dalton’s law?
in a gas mixture, the pressure exerted by each individual gas in independent of the pressures of the other gases in the mixture
how do you calculate partial pressure?
% of total gas mixture times total ressure
define dry atmospheric air?
completly devoid of air
what tow things happen to air when you breath it through nose?
1) warmed to 37 celcius
2) 100% humidified to exert 47 torr
what are standard condition of air we breath?
37 degrees C
100% humidified to exert 47 torr
O2 =21% of atmosphere
inspired air at 100% humidified at 37 degrees exerts ____ torr
47
is humidified 47 torr part of 760?
yes. You must substract 760- 47 = 713
how do you calculate oartial pressure?
% of total gas mixture multiplies by total pressure
PO2 vs OiO2 vs P,AO2?
- PiO2= PP of INspired oxygen
- P,A = PP of alveolar oxygen
what changes your calculations of PP?
atmospheric pressure! (aka total barometric pressure)
what greatly affects barometric pressure?
altitude
what are typical #s of inspired and alveolar gas?
Inspired
- PiO2= 150
- CO2= 0
alveolar
- PaO2= 100
- CO2= 40
what determiens PaO2 and PaCO2?
1) alveolar ventilation
2) O2 uptake from and CO2 delivery to the lung
why isn’t alveolar gas PPs for O2 150 like when it is inspired?
O2 is castantly diffusiong out of alveoli into pulmonary capillaries. So even at rest, you can’t fill up to 150 bc O2 is always leaving (can’t fill up bath with a drain open)
**same thing happens with CO2 but in other direction
alveolar oxygen and CO2 are regulated by?
alveolar ventilation rates
hypo vs hyperventilation relationship woth O2 and CO2 levels?
- hypo= increase CO2; decrease O2
* hyper= decrease CO2; increase O2
normall ventilation of gas is about?
100
why is O2 and CO2 relationship different?
bc we have a cap on how much oxygen we have. It is really determined by atmosphere
at sea level, inspired O2 is at 150 meaning?
the highest you can drive O2 levels is 150
*so until that point, you have somewhat of a direct relationship bw alveolar ventilation and alveolar oxygen
the amount of PP CO2 and O2 in alveoli in a typical healthy person regulates how much is in?
arterial blood
driving force for simple diffusion?
either pressure or concentration gradients
diffusivity of CO2 or O2 is greater?
CO2
partial pressure of CO2 or O2 is greater?
O2
how do this factors affect diffusion rate?
1) excericise
2) emphysema
3) pulmonary edema
4) alveolar fibrosis
5) supplemental oxygen
1) increase surface area
2) decrease SA and causes impairment
3) increase thickness and causes impairment
4) increase thickness and causes impairment
5) increases P1 - P2
metabolically active cells have a lower PP intracellularly or extracellularly?
intracellularly
* lower PP = greater PP gradient of O2 = more O2 will diffuse into cell
what happens with CO2 and O2 in metabolically active cells?
O2= influx CO2= efflux (exit cells)
