Flashcards in Control of Respiration Deck (18):
Compare the partial pressures of CO2 in the atmosphere and in the alveolus.
Atmosphere - 0.3mmHg, <1%
Alveolus - 40mmHg
Compare the partial pressure of CO2 in the atmosphere and in the alveolus.
Atmosphere - 159mmHg
Alveolus - 105mmHg
Why is the partial pressure of O2 lower in the alveolus than in the atmosphere?
Increase in partial pressures of CO2 and water vapour.
Compare the partial pressure of O2 and CO2 in the pre-alveolar capillaries and post-alveolar capillaries.
PO2 = 40mmHg, PCO2 = 45mmHg
PO2 = 100mmHg, PCO2 = 40mmHg
Explain Henry's Law
When a liquid is exposed to a gas, the amount of gas dissolving into the liquid is directly proportional to the partial pressure of the gas.
List the factors affecting diffusion across capillary walls.
Partial pressure gradient, thickness of the membrane, SA of the membrane, diffusion coefficient of the gas in substance of the membrane
Compare the rates of diffusion of O2 and CO2 across the capillary wall.
CO2 diffuses 20x faster than O2
How does pulmonary oedema affect gas diffusion?
Gas needs to diffuse across the fluid in addition to the membrane.
How does fibrosis affect gas diffusion?
Increases the thickness of the respiratory membrane.
How does emphysema affect gas diffusion?
Reduces SA of alveolar walls.
Compare the oxygen carrying capacities of Hb to water and plasma.
Compare the PO2 in blood leaving the lungs and returning to the lungs.
97% (95mmHg) vs 75% (40mmHg)
Explain the Bohr effect.
A rise in PCO2 increases H+ concentration, lowering the pH and decreasing O2-Hb binding capacity. O2 delivery/off-loading in increased. Important in tissues.
List factors that shift the O2 saturation curve to the right.
Increased H+, CO2, temperature and BPG.
Explain the Haldane effect.
An increase in O2 increases offloading of CO2. Important in lungs.
What is the effect of CO on O2-Hb binding?
CO has high affinity for Hb, displacing O2. Decreases O2 release, shifting the curve to the left and decreasing O2 delivery.
What are the three ways in which CO2 is transported in blood?
Dissolved in blood (5-10%)
Bicarbonate ions HCO3- in plasma (60-70%)