16) IN NORMAL BLOOD

[Editor]

a) 20 mls of oxygen is carried per 100 mls of venous blood
b) oxygen combines with globin in haemoglobin
c) viscosity is predominantly due to red cell mass
d) as velocity increases red cells accumulate in the centre of vessels
e) red cells metabolise glucose

[Editor]

FFTTT

Oxygen content= HB times 1.34 times sats/100 + dissolved fraction. This equates to 20 mls per dl for arterial blood but only 15mls/dl fro venous blood. The oxygen actually binds to the haem molecule not the globin chain. As red cell concentration increases (polycythaemia) the viscosity increases. This may affect delivery if the blood is very viscous. Red cells are anucleate but do need glucose to perform normal enzymatic reactions.