Gas Transport Flashcards
Hemoglobin/O2 ratio
1.34 ml O2 per Hb
O2 capacity calculation
(Hb concentration/dl) * (1.34 ml O2/Hb)
what does O2 capacity tell us?
the amount of O2 that can be carried in the blood
Oxygen saturation
% of O2 binding sites on Heme
Oxygen content: definition and calculation
amount of oxygen that is actually being carried. calculated using O2 capacity times oxygen saturation
the amount of oxygen that binds to heme is proportional the PO2 in the lungs: does that mean the volumes are equal?
no. it just means there’s an equilibrium between dissolved O2 and O2 bound to heme
normal arterial volume of oxygen =
assuming am Hb of 15 g/dl
(1.34 ml O2/g Hb) x (15g/dl blood) = 20.1 ml O2/dl blood
what is the normal amount of blood carried per deciliter in the blood?
20.1 ml O2/dl blood
oxygen capacity
(1. 34 ml O2/g Hb) x (15g/dl blood) = 20.1 ml O2/dl blood
20. 1 ml O2/dl blood
oxygen content =
(1. 34 ml O2/g Hb) x (15g/dl blood) = 20.1 ml O2/dl blood
(20. 1 ml O2/dl)x(95% saturation) = 19.1 ml O2/dl blood
Capacity vs content
amount that CAN be carried vs amount that IS carried
capacity: (quantity if Hb in the blood grams x 1.34 ml O2/g Hb)
content: capacity x % saturation
On the Hb-O2 binding curve, where are the high P02’s found?
in the lungs
Flat portion of the graph corresponds to what amount of P02 pressure?
around 60 and above, which indicates an 85%+ saturation at least
Steep portion of the Hb-O2 curve corresponds to what range
what does a steep slope indicate
10-65 mmHg PO2
high affinity for oxygen
P50
what this number indicates and how to locate it on the X axis
partial pressure that indicates 50% of Hb is saturated
draw a horizontal to the curve, then draw a vertical down to the X axis
the normal P50 of an adult is about 27 mmHg P02
why is P50 important
reflects affinity of hemoglobin for oxygen
adult hemoglobin has as an affinity for oxygen around
27 mm Hg PO2 on the Hb-O2 curve
fetal hemoglobin as an affinity for oxygen around
less than 20 mmHg on the Hb-O2 curve
pathologies involving hemoglobin cause the Hb-O2 curve to register
saturation above 27 mm Hg (Hb has a lower affinity than normal)
DPG
a metabolite produced during anaerobic metabolism, increase in DPG causes a right shift, decreasing Hb affinity for O2
