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pulmonary gas exchange (alveolar) (respiratory unit/ respiratory lobule,…
pulmonary gas exchange
(alveolar)
means exchange of gases
betw the alveolar air
and the blood
in the pulm capillaries
the gase exchange by diffusion
net diffusion of gases will
occure from high conc to low conc
o2 from alveoli diffuses into pulm blood
co2 from pulm blood diffuses into alveoli
rate of diffusion is directly proportional
to the partial pressure of the gas
partial pressure- the pressure caused
by that gas in a mixt of gases
respiratory unit/
respiratory lobule
composed of
respiratory bronchiole
alveolar ducts
atria
alveoli
respiratory membrane
layers,
1.fluid & surfactant layers
2.alveolar epithelium
3.epithelial basement membrane
4.intestitial space
5.capillary basement membrane
6.capillary endothelial membrane
thickness
0.2-0.6 micro meters
total surface area of both lungs
70 squaremeters
factors affecting the rate of gas diffusion
1.thickness of the membrane
SA of the membrane
3.the diffusion coeficient of the gas
solubility/square root of molecular weight
the partial pressure difference of the gas betw
the 2 side of the membrane
o2 transport
o2 diffuses from alveoli
to pul capillary blood
`higher PO2 in the capillary
blood than in the tissues
to surrounding cells
o2 is metabolised in the cells to
form co2
co2 transport
co2 diffuses
from the cells
to tissue capillaries
after blood flows to lungs
co2 diffuses out of
blood
to alveoli
so the transport of
o2 & co2
by the blood
depends on both
diffusion
&
flow of blood