Flashcards in Session 10_Respiratory System and Gas Exchange Deck (185)
What is emphysema?
lung condition characterized by an abnormal, permanent enlargement of the air spaces distal to the terminal bronchioles accompanied by destruction of their walls.
Why are people with emphysema short of breath?
(irreversible alveolar damage resulting in loss of elastic recoil and the normal tethering of the alveolar, which renders the lung parenchyma excessively compliant and floppy. Excessive distension and dilatation of the terminal bronchioles and destruction of alveoli reduce the surface area for gas exchange. --> diffusing capacity is reduced.
Dead space in lungs and TLC increase.
Breathing at normal tidal volume, the pts airways close beyond the degree normally occurring with aging, contributing to ventilation and per-fusion mismatch and hypoxemia.
What causes emphysema?
prolonged history of smoking and chronic bronchitis. indicates significant irreversible lung damage.
process of randomly moving molecules making their way back and forth across the respiratory membrane
What determines movement of gases?
concentration; high --> low
Dalton's law of PP =
Ptotal = P1+ P2+ P3.. etc
What type of motion does diffusion require?
What gases are in the atmospheric pressure?
oxygen, nitrogen, carbon dioxide and water
How much oxygen is in the atmospheric pressure?
20.84% of 760mmHg = (158.384mmHg)
How much nitrogen is in the atmospheric pressure?
78.62% of 760mmHg = (597.512mmHg)
How much carbon dioxide is in the atmospheric pressure?
0.04% of 760mmHg = (.304mmHg)
How much water is in the atmospheric pressure?
0.5% of 760mmHg = (3.8mmHg)
Pressure creates a ___________ impact on the surface
Partital pressure =
multiple gases in air
Each gas exerts a pressure (partial pressure of whole); rate of diffusion is directly related to:
partial pressure of a gas
Total pressure at sea level =
Gases dissolved in fluids continue to:
Partial pressure of a gas in fluid is determined by:
• solubility coefficient of the gas
solubility coefficient of the gas is related to the partial pressure which is equal to =
concentration of dissolved gas / (divided by) solubility coefficient
What is the solubility coefficient of atmospheric O2?
What is the solubility coefficient of CO2?
Alveolar gas and molecules of same gas dissolved in:
What will be the direction of the net diffusion of the gas?
depends on multiple factors.
What factors does net rate of diffusion depend on?
• pressure difference
• solubility of the gas in the fluid
• cross-sectional area of the fluid
• distance the gas must diffuse
• molecular weight of the gas
• temperature of the fluid
Gas diffusion (D) is proportional to:
∆ P x A (cross sectional area) x S (solubility) / d (distance of diffusion) x square root of MW (molecular weight)
∆ P x A x S / d x √MW
PP difference -->
PP @ arterial end and PP @ venous end
Diffusion coefficient =
relative rate that gases @ same PP will diffuse
Diffusion coefficient of oxygen =
Diffusion coefficient of carbon dioxide =