Flashcards in Quiz 4 Physical Princiles of Gas Exchange Deck (50):
What is the mechanism and rate of molecule transfer dependent on ?
-Physics of gas diffusion
-Partial pressures of gases involved.
What is the energy source for gas diffusion?
Molecular movement is continual and random?
Movement of a gas in one direction is the effect of what?
Direction of diffusion occurs for areas of ______ to _______ concentration.
Rate of diffusion is dependent on what?
What is partial pressure?
The pressure a gas would exert by it's self.
What is the total pressure of a mixture?
The summation of all the partial pressures in a gas.
Each gas exerts its own individual pressure on the respiratory wall surface?
What is the mixture of air?
What is the total pressure of the air mixture?
760 mm Hg
What does 1 atmosphere equal?
760 mm Hg
What is the partial pressure of nitrogen in one atmosphere?
600 mm Hg
What is the partial pressure of oxygen in one atmosphere?
160 mm Hg
What does Henry's Law say about the solubility of a gas in a liquid?
Depends on the
-partial pressure of the gas over the liquid
-nature of the solvent
-nature of the gas
What is high soluble mean?
When dissolved molecules are attracted by water more can be accumulated without building up excess pressure in a solution.
What does poorly soluble mean?
Molecules which are repelled by water will dissolve less and have lower concentration
What is the rate of net diffusion determined by?
Difference of partial pressure (pp).
If the pp of gas in the alveoli greater than blood which way will the gas move?
The gas will move into the blood.
What is the vapor pressure when a gas mixture is fully humidified at 37 C?
What is vapor pressure of water?
Partial pressure of water escaping surface into gas phase.
What factors affect gas diffusion rates in fluid?
-gas solubility in fluid
-area of fluid
-Distance which gas must diffuse
-molecular weight of gas
-Temperature of fluid
What is diffusion coefficient of the gas?
characteristics of the gas which affect the ability and rate of net diffusion.
(Solubility/ *square root* Molecular weight)
What is the limiting factor for gas movement into tissues?
diffusion rate of gas through tissue water.
Alveolar air does NOT have the same gas concentration as atmospheric air?
How many normal alveolar ventilation removes half of the gas?
What is the normal alveolar PO2?
100 mm Hg
What is the normal alveolar PCO2?
40 mm Hg
Alveolar air is ______ at end of exhalation.
How thick is the alveolar membrane?
What is the total surface area of the alveolar?
70 square meters
How wide is the alveolar capillaries?
What are the factors that affect rate of gas diffusion through the respiratory membrane?
1. Thickness of the membrane
2. Surface area of the membrane
3. Diffusion coefficient
4. pressure difference across the membrane
CO2 diffuses ___ times faster than Oxygen.
Oxygen diffuses _______ as rapidly as nitrogen.
Can the factors which affect diffusion through the respiratory membrane affect the diffusion capacity?
What is the diffusing capacity?
Volume of a gas that will diffuse through the respiratory membrane each minute for a pressure difference of 1 mm Hg.
What is the diffusing capacity for O2?
How do you get the total quanitity of O2 diffusing across the membrane per minute?
Pressure difference multiplied by the diffusing capacity.
How much does exercising increases the diffusing capacity to?
What increases the diffusion capacity during exercising?
-recruiment of capillary fields
-better ventilation/perfusion match with blood (All ZONE 3)
CO2 diffusing capacity estimates based on ______ _______.
Diffusing capacity of CO2 at resting is ________ and during exercise is ______?
If the V/Q ratio is either zero or infinity there is ______ exchange of gases.
When V/Q = Zero this means what?
There is no ventilation
When V/Q = infinity this means what?
There is no perfusion
Normal deoxygenated blood PO2 is _____..
Normal deoxygenated blood PCO2 is _____.
Inspired air PO2 is ______ mmHg