lecture 18 Flashcards
whats alveolar ventilation
the volume of air which actually reaches the alveoli
whats the equation for alveolar ventilation
(Vt - Vd) x f
whats daltons law
the pressure of a gaseous mixture equals the sum total of the pressures of each individual gas
what are the determinants of the rate of diffusion?
surface area of the membranes
thickness of the membranes
pressure difference between the two sides
whats the equation for gas diffusion rate across membranes
F= (AD(P1-P2))
===========
T
F=flux (amount flowing) A=surface area
D= diffusion constant T=thickness
p1-p2= pressure difference
what does D depend on and how does it apply to O2 and CO2
gas solubility and molecular weight. CO2 diffuses around 20x faster as its more soluble
what is emphysema
it’s a chronic obstructive lung disorder, it is a disease whereby the alveolar spaces are dilated and alveoli walls are destroyed
what can effect the thickness of the exchange surfaces
the thickening and scarring of alveolar membranes, this is pulmonary fibrosis.
whats the main factor of gas transfer by diffusion
pressure difference between arterial and alveoli
what does alveolar partial pressure of oxygen depend on
PO2 of inspired air, alveolar ventilation, Oxygen consumption
when we exercise what happens related to oxygen consumption
we have high activity, so we are using more oxygen for metabolism, This means less oxygen in the blood so there is thus a greater driving force of oxygen into the blood stream. as less pressure
the alveolar partial pressure of CO2 depends on what
partial pressure of CO2 inspired, alveolar ventilation and CO2 production,
Alveolar PCO2 is usually determined only by the balance between carbon dioxide production
and alveolar ventilation, because atmospheric PCO2 is negligible
