Gas Exchange And O2 CO2 Transport Flashcards
Random motion of molecules in all directions through the respiratory membrane and adjacent fluids
Diffusion
Caused by multiple impacts of moving molecules against a surface
Pressure
True or False
Pressure is directly proportional to the concentration of gas molecules
True
In respiratory physiology, one deals with mixture of gases:
Oxygen
Nitrogen
Carbon dioxide
Rate of diffusion of each of these gases directly proportional to the pressure cause by that gas alone
Partial pressure
Gases dissoleved in water or in body of tissues also exert pressure because
The dissolved gas molecule are moving randomly and have kinetic energy
Factors that determine the partial pressure of a gas dissolved in a fluid
Concentration/
Solubility coefficient of the gas
=partial pessure
Solubility coefficient highest to lowest
CO2>oxygen>CO>N>He
Which factor in the alveolar respiratory gas mixture tends to force molecules of that gas into solution in the blood of the alveolar capillaries
Partial prssure
In which direction will net diffusion of the gas occur?
In oxygen, more molecules will diffuse into the blood because PO2 is greater in the gas phase
In CO2, PCO2 is greater in the dissolved state so net diffusuon will occur toward the gas phase in the alveoli
Partial pressure that the water molecules exert to escape through the surface is called
Vapor pressure or PH2O
Vapor pressure normal value
47 mmHg
Factors that affect the rate of gas diffusion in the fluid (5)
Solubility of the gas on the fluid Cross sectional area of the fluid Distance through which the gas must diffuse Molecular weight of the gas Temperature of the fluid
(Soul Cross, Mold dis temp!)
The greater the solubility of the gas, the lesser the number of molecules available to diffuse
True or False
False. Lesser must be greater
These two factors determine the diffusion coefficient of the gas
Solubility and molecular weight
The relative rate at which different gases at the same partial pressure levels will diffuse
diffusion coefficient of the gas
Relative diffusion coefficients ranked:
CO2>O2>He>CO>N
The major limitation to the movt of gases in tissues
Rate at which the gases can diffuse through the tissue instead of the cell membranes
All are correct except:
A. Alveolar air is completely replaced with alveolar air with each breath
B. O2 is constantly absorbed into the pulmonary blood from the alveolar air
C. CO2 is constantly diffusing from the pulmonary blood into the alveoli
D. Dry atm air that enters the respi passages are being humidified even before it reaches the alveoli
A.Only partially
Composition of atm air except
N
O2
CO2
Water vapor
CO2 almost none
True or False
Total pressure in the alveoli can rise to more than the atm pressure (760mmHg at sea level) that this water vapor simply concentrates all the other gases in the humidification of the air
False. Cannot. Dilutes
Volume of alveolar air replaced by new atm air with each breath is only 1/6 of the total so multiple breaths are required to exchange most of the alveolar air.
T/F
1/7
Slow replacement if alveolar air is impt in
A. Preventing sudden changes in gas conc in the blood
B. Makes respo ctrl much more stable
C. Helps prevent excessive increases and decreases in tissue oxygenation, tissue CO2, and tissue pH when respiration is temp interrupted
D. AOTA
D.
O2 conc in the alveoli as well as its partial pressure is controlled by
Rate of absorption of O2 into the blood
Rate of entry of new O2 into the lungs by the ventilatory process
