Blood supply, gas exchange, ventilation and perfusion 1 Flashcards
(28 cards)
What gradient does Po2 go down from alveoli to circulation?
100mmHg in alveoli to 40mmHg in circulation.
What gradient does Pco2 go down from circulation to alveoli?
46mmHg in circulation to 40mmHg in alveoli.
What gradient does Po2 go down from circulation to tissues?
100mmHg in circulation to >_40mmHg
What gradient does Pco2 go down from circulation to tissues?
46mmHG in tissues to >_40mmHg in circulation
True or false : The rate of diffusion across the membrane is directly proportional to partial pressure gradient.
True
True or false: The rate of diffusion is inversely proportional to gas solubility.
False. It is directly proportional.
True or false: The rate of diffusion is inversely proportional to thickness of membrane.
True
Will air continue to move across the membrane until equilibrium is reached?
Yes
There is a larger gradient between Po2 compared to Pco2. so how come pco2 diffuses almost as fast? (200ml/min compared to 250ml/min)
Because co2 is much more soluble than o2, so can travel faster.
What is optimal condition for gas exchange?
when ventilation = blood flow. ( the amount of air going into alveoli should match the amount of blood flowing past them in arterioles.)
What does distribution of blood flow around the alveoli depend on?
hydrostatic (blood) pressure & alveolar pressure.
Describe the blood flow, arteriole pressure, vascular resistance etc. at the top of the lung.
top of lung, low blood flow . alveolar pressure is more than arteriole pressure. vascular resistance is increased.
Describe the blood flow, arterial pressure, resistance etc. at the bottom of the lung.
Bottom of the lung has high blood flow. The arterial pressure is more than alveolar pressure, low vascular resistance.
What happens when blood flow is higher than ventilation?
Deoxygenated blood just flows past the alveoli without picking up oxygen - SHUNT.
What is alveolar dead space?
ventilation is higher than blood flow. The alveoli are ventilated but not perfused.
what is physiological dead space?
alveolar dead space + anatomical dead space
what is emphysema? (affects gas exchange)
destruction of alveoli reduces surface tension.
What is fibrotic? (affects gas exchange)
thickened alveoli membrane slows down gas exchange
what is pulmonary edema? (affects gas exchange)
fluid in interstitial space.
why does pulmonary edema not affect co2 as much as o2?
Because co2 is much more soluble.
what is asthma? (affects gas exchange)
increase airway resistance, decrease airway ventilation. (no barrier to diffusion, but there is less o2 in the actual alveoli.
What circulation supplies oxygenated blood to airway smooth muscle, nerves and lung tissue?
Bronchial circulation - via bronchial arteries.
Is the pulmonary circulation a high flow and low pressure system?
yes. it is 25mmHg compared to 120mmHg systematic circulation.
what does a sample of arteriole blood tell you about and why?
lungs - as they are in equilibrium
