Lecture 20 - Gas Exchange Flashcards
What does Dalton’s law of partial pressure state?
That the total pressure exerted by a mixture of gases is the sum of the partial pressure exerted by each gas n the mixture
What does Henry’s law state?
When a mixture of gases is in contact with a liquid, each gas will dissolve in the liquid proportion to its partial pressure
What does the amount of each gas dissolved depend on?
Solubility: some gases dissolve more easily.
O2 is 24 ́ more soluble in water than O2.
O2 is 2 ́ more soluble in water than N2.
temperature: as the temperature of a liquid rises, solubility decreases.
Where does a steep partial pressure gradient exist?
Between the air in the alveoli and the gases in pulmonary artery blood
O2 diffuses from the alveoli into blood. CO2 moves in opposite direction, diffusing out of blood and into alveoli.
Ventilation perfusion coupling
Matching of alveolar ventilation (air reaching alveoli) with pulmonary blood perfusion ( blood reaching alveoli)
Why are ventilation and perfusion balanced?
So that they can work together to make O2 and CO2 levels match physiological demands
Po2
Controls perfusion by changing arteriolar diameter
In order to optimize perfusion and maximize oxygen uptake into blood, arterioles feeding areas with low PO2 constrict and arterioles serving well ventilated areas dilate.
pco2
Controls ventilations by changing bronchioles diameter
To increase ventilation so there is more rapid release of CO2, bronchioles serving areas with high alveolar CO2 dilate and areas with low CO2, bronchioles constrict
Internal respiration
Involves capillary gas exchange in body tissues
Why does hemoglobin’s affinity for oxygen change?
It changes with each successive oxygen that is bound or released, making oxygen loading and unloading very efficient
The larger the difference between the amount of oxygen in tissue and the amount of oxygen in blood, the more……?
Easily oxygen will detach fm hemoglobin and diffuse into the tissue
Why does large change sin amount of available oxygen in air hav very little effect on O2 saturation?
Because the O2 saturation curve is relatively flat at high Po2
What happen at low Po2?
Hemoglobin easily releases oxygen to body tissues
What happens at higher plasma partial pressures of oxygen?
hemoglobin unloads little oxygen
What happens at low plasma partial pressure?
more oxygen can be unloaded to the tissues.
