Two types of gas movement
barometric pressure
Oxygen diffusion gradient
Transit time
about 0.75 seconds
Time for capillary plasma P02 to = alveolar P02
1/3 the time it takes to move through a capillary
Diffusion capacity
affected by hematocrit and pulmonary blood volume
O2 + hemoglobin?
rapid and reversible binding
Most common form of bound 02 in blood
otherwise 2% is dissolved in plasma
Where 02 binds with hemoglobin
Where 02 is released from hemoglobin
oxygen saturation
compared with the capacity to bind
P50
Normal P50 levels (in mmHg)
Oxyhemoglobin curve shifts left
less unloading of 02 at tissue level
Oxyhemoglobin curve shifts right
more unloading of 02 at tissue level
2,3 DPG
found in red blood cells, causes right curve shift
Decrease in pH, increase in CO2
Exercise effect on curve
makes 02 readily available for muscle in the plasma
Pa02
measures free 02 molecules in plasma, doesn't measure 02 bound by HGB
Sa02
in arterial blood
Ca02
only measure that incorporates amount of hemoglobin
210 greater affinity for HGB than 02
odorless and colorless, makes blood bright red, no cyanosis
Most common way CO2 is carried in blood
60%. Other ways are plasma (10%) and carbamino protein (30%)
Carbonic acid and pH
able to rapidly release or bind H+
Normal pH range
Normal Ca02 level
Pa02
Hypercapnia
levels above 48
Normal Va/Q ratio
What ventilation and perfusion should be in lungs
Leads to lower Va/Q ratio
one section of airway is not properly ventilated, blood is not getting perfused adequately
Two causes of diffusion block
decreased permeability across alveolar membrane