Arterial blood gases and acid-base disorders Flashcards
what is the role of dissolved oxygen?
diffuses from lungs into blood
enters RBCs
binds Hb
what are the features of the T form of Hb?
- oxygen binds to alpha subunit of Hb
- conformational change increases oxygen affinity of second alpha subunit
- rotation of two a/B dimers with respect to each other
T form to R form transition
- oxygen binding sites on beta subunits available
2. beta subunits rapidly bind oxygen
which Hb form has high affinity for oxygen?
R
what stabilizes the T form of Hb? what is the implication for oxygen affinity?
anything that increases or strengthens contact between subunits (salt bridges, eg)
reduced oxygen affinity
what do lower 2,3-BPG and high [CO2] do to Hb?
stabilize T form
reduced oxygen affinity - oxygen unloading in tissues
what stabilizes the R form of Hb? what is the implication for oxygen affinity?
anything that dminishes or weakens the contacts between subunits
increased oxygen affinity
what do higher 2,3-BPG and low [CO2] do to Hb?
increase oxygen affinity
CO2 attaches to Hb as what compound?
N terminal carbamates
CO2 is transported in the blood as what forms? what is the major form?
dissolved
N terminal carbamates (Hb)
bicarbonate ion (majority)
what is generated by the formation of carbamates and bicarbonate?
protons
what is the Haldane effect?
CO2 concentration of blood varies as a function of bloody oxygenation
less total CO2 in oxygenated blood
more total CO2 in deoxygenated blood
which is a stronger base - deoxyHb or oxygenated Hb?
deoxyHb
what does proton binding do to oxygen affinity of Hb? what does it facilitate?
decreases - facilitates oxygen unloading
what is the major buffering system in the blood?
bicarbonate buffer system
