RS Lec 6 Flashcards
O2 in blood forms
- dissolved (2%)
- combined with hemoglobin (98%)
dissolved O2 proportional to (2)
PO2
solubility
98% (197 ml/L) of O2 carried on
hemoglobin in red blood cells
hemoglobin made of
- globins: 4 subunits (a.a) - 2 alpha/ 2 beta
- 4 heme groups
heme (def.)
porphyrin ring structure that has Fe2+ that O2 binds
each HB molecule can bind
4 O2- one per subunit (O2 + Hb HbO2)
Hb
deoxyhemoglobin
HbO2
oxyhemoglobin
O2 capacity
max amount of O2 that is combined with Hb
1 g Hb combines with (amount of O2)
1.39 ml O2
normal conditions (g Hb/ 100 ml blood)
15g Hb/100 ml
max O2 capacity (g Hb/100 ml)
20.8 ml O2/100 ml blood
Hb saturation
- percentage of available Hb binding sites that have O2 attached
- O2 with Hb/ O2 capacity x 100%
Hb saturation of arterial blood (100 mmHg PO2)
97.5%
Hb saturation of mixed venous blood (40 mmHg PO2)
75%
factors that determine Hb saturation
- arterial PO2 (most important)
- cooperative binding (sigmoidal dissociation curve)
dissociation curve sensitive to
- pH
- pCO2
- temp.
cooperative binding
O2 binding causes change from T (tense) to R (relaxed) state in a globin, facilitates change in other globin and additional O2 binding