Respiration Part 5 Flashcards
What are the Factors that Affect the Pressure of Gas dissolved in a fluid?
•Concentration
• Solubility coefficient of ;
02: 0.024
CO2: 0.57
What does this stand for?Do A P•A•S•T/d MW
• D: diffusion rate
• A P: pressure difference
• T: temperature
• A: cross-sectional area of the pathway
• S: solubility of the gas
• d: the distance of diffusion
• MW: molecular weight of the gas
What does S/dVMW mean?
diffusion coefficient of the gas;
oxygen 1.0 carbon dioxide 20.3 carbon monoxide 0.81
What is the normal gas pressure of O2 in Venous blood,Arterial blood,alveoli and atmosphere?
PO2 in Venous blood:40mmHg
in Arterial Blood:100mmHg
In Alveoli :105mmHg
In the Atmosphere:160mmHg
What is the normal gas pressure of CO2 ?
In Venous blood:46mmHg
In Arterial blood:40mmHg
In Alveoli:40mmHg
In Atmosphere:0.3mmHg
Where does GAS EXCHANGE BETWEEN ALVEOLI AND
BLOOD occur?
Respiratory membrane
What does the respiratory membrane consist of?
•layer of fluid lining the alveolus and
containing surfactant
‹ the alveolar epithelium
• an epithelial basement membrane
• a thin interstitial space between the alveolar epithelium and the capillary
membrane
• a capillary basement membrane
• the capillary endothelial membrane
What is the thickness of the respiratory membrane?
0.6 micrometers
What are Factors affecting gas exchange across
the respiratory membrane?
a) Thickness of the membrane
b) Surface area of the membrane
c) Diffusion coefficient of the gas d) Partial pressure of gases across
the membrane (driving force)
e) Ventilation/perfusion ratio
What is Ventricular/Perfusion Ratio
VA/Q
= (4.2 L/min)/(5 L/min)
=0.84
What is the Main effect of Ventilation/perfusion ratio?
Decrease the POz of systemic arterial blood
Distribution of ventilation and perfusion is different:
• VA/Q at the bottom of the lung: 0.63
at the apex of the lung: 3.3
