Lecture 24- Pulmonary gas exchange Flashcards
what element is has the highest composition in both atmospheric pressure and at alveoli saturated with 6.18% water vapor
Nitrogen
total pressure exerted by the mixture of non-reactive gases is equal to the sum of the partial pressures of individual gases
dalton’s law
for a fixed amount of an ideal gas kept at a fixed temperature, pressure and volume are inversely proportional
boyle’s law
at a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid
henry’s law
what is the ideal gas law
P= nRT/V
what is the partial pressure of O2 at alveolar membrane
150 mm Hg
what is the partial pressure of CO2 at alveolar membrane
0.12 mm Hg
what is the solubility of oxygen and carbon dioxide and what does this mean
oxygen= 0.024
CO2= 0.57
CO2 is more soluble in water than oxygen and therefore will exert a partial pressure for a given concentration that is less than 1/20th that of oxygen
define vapor pressure of water
partial pressure exerted to escape form liquid phase to the gas phase
what is the value for vapor pressure at normal body temperature
47 mm Hg
what factors affect rate of gas diffusion in a fluid
solubility of gas in fluid cross-sectional area of the fluid distance through which the gas must diffuse molecular weight of gas temperature of fluid
what is the value for the functional residual capacity of the lungs in the average man
2300 ml
what is oxygen concentration in the alveoli and its partial pressure controlled by
rate of absorption of oxygen in the blood
rate of new oxygen entry into the lungs (alveolar ventilation)
what is carbon dioxide concentration in the alveoli and its partial pressure controlled by
rate of CO2 excretion
alveolar ventilation
what happens to alveolar PCO2 as alveolar ventilation increase
it decreases
what happens to alveolar PCO2 as rate of excretion increases
it increases
what factors determine how rapidly gas will pass through the respiratory membrane
membrane thickness
membrane surface area
diffusion coefficient of gas in the substance of the membrane
partial pressure difference of gas between the 2 sides of the membrane
define ventilation-perfusion ratio
alveolar ventilation/blood flow
what is the normal Va/Q
0.8
where is gas exchange completed during normal ventilation
initial 1/3 of capillary
what happens to blood gas composition when there is an airway obstruction
it remains unchanged
what happens to alveolar gas composition when there is a vascular obstruction and why
it does not change because there is no blood contact (creating a physiologic shunt)
what is the normal alveolar perfusion for PO2 and PCO2
PO2= 104mm Hg PCO2= 40 mm Hg
what are the alveoli partial pressure of O2 and CO2 when Va/Q is infinity
O2= 149mm Hg CO2= 0 mm Hg
