Respiratory Physiology III: Pulmonary Gas Exchange (Exam 4) Flashcards
Blood coming into the capillaries (before diffusion) through the pulmonary artery:
PO2:
PCO2:
PO2: 40mmHg
PCO2: 45 mmHg
In the alveoli:
PAO2:
PACO2:
PAO2: 100mmHg
PACO2: 40mmHg
Blood exiting the capillaries (after diffusion) through the pulmonary vein:
PO2:
PCO2:
PO2: 100mmHg
PCO2: 40mmHg
When blood reaches the pulmonary vein, the PO2 and PCO2 have reached:
equilibrium
When blood enters the left heart, the PO2 is actually at ____. This is due to ___.
PO2= 95mmHg
This is due to bronchial circulation
To calculate a partial pressure, you must determine the ____ of the gas to other molecules
relative concentration
Refers to the pressures of one gas in a mixture of gases
partial pressure (Pgas)
Equation for partial pressure of a gas:
Pgas= PATM x fractional concentration of gas
The atmospheric pressure (PATM) at sea level is ____ and air is composed of ____.
760mmHg; 79% nitrogen & 21% oxygen
Fraction of inspired oxygen:
FiO2
Calculate the partial pressure of oxygen in our atmosphere:
PO2= 760 x 0.21 = 160mmHg
As air passes through the conducting zone of the lung, it is humidified creating:
a partial vapor pressure for water
As air passes through the conducting zone of the lung, it is humidified creating a partial (vapor) pressure for water (PH2O = 47mmHg). This addition of water does what to the partial pressure of oxygen?
decreases
Calculate the partial pressure of oxygen with the addition of the partial vapor pressure of water at 47mmHg
PO2= (760mmHg - 47mmHg) x 0.21 = 149mmHg
At normal alveolar ventilation and O2 absorption rates (250ml/min), PAO2 is:
100mmHg
Increasing alveolar ventilation will ____ PAO2
increase
Equation for alveolar ventilation:
Alveolar ventilation = (TV-DS) x RR
According to the equation:
Alveolar ventilation = (TV-DS) x RR, you can increase alveolar ventilation by:
increasing TV or RR
A gas within a liquid also exerts a _____.
partial pressure
To calculate a partial pressure in a liquid solution, the ____ and the ____ of the gas are required
relative concentration; and solubility coefficient
Attractability of molecules to water:
solubility coefficient
If the solubility coefficient number is high:
the gas diffuses in the liquid quickly
Henry’s Law:
Partial pressure = (concentration of dissolved gas) / (solubility coefficient)
Concentration of dissolved gas equation: (rearrangement of henry’s law)
Conc. of dissolved gas= solubility coefficient x partial pressure
At a constant temp, the amount of a gas that dissolve in liquid id _____ to the partial pressure and solubility
directly proportional
Compare the solubility of CO2 to O2:
CO2 is more soluble than O2
Why would a patient who has trouble oxygenating their blood be able to transport & get rid of CO2 more easily?
Because CO2 is more soluble
The higher the partial pressure of the gas, the ____ we will be able to dissolve into the liquid
more
Gas exchange at the respiratory membrane depends on:
- transport rate through the respiratory membrane
- The rate of alveolar ventilation
An increase in alveolar ventilation will ___ PAO2 and gas exchange with an upper limit of ____ which is ____.
increase; 149mmHg; the PAO2 of humidified air
The rate of alveolar ventilation has upper limit of 149mmHg. Describe a scenario where this limit might surpassed:
Patients that are on oxygen may have higher FiO2 (fraction of inspired oxygen) than 21% which would increase the partial pressure of oxygen
