L18- blood gases Flashcards
factors affecting amount of gas taken up for transport
- how much gas contained in a litre of blood whether it’s transported in solution or bound to carrier molecules
- amount of blood transported so CO
- modulation of gas content in blood
what is flux or flow
how many litres of gas per min are transported
formula for gas or substance dissolved
partial pressure x solubility coefficient (alpha)
is O2 or CO2 more dissolved
CO2 even with a lower partial pressure
types of gas carrier molecules
-Hb
properties of Hb
- has a haem group that binds to each 02 molevcule
- carries both O2 and CO2 and buffers pH
- has aplha and beta chains and they binds to CO2 and H+
- beta chains binds to 2,3-DPG
when the metabolic gases bind to a protein, it’s no longer in what
in solution so it doesnt move across the partial pressure gradient
what happens to the HB binding with O2 as the PO2 increases
-more O2 bound to HB so the saturation increases producing sigmoid curve
saturation of Hb eqn
(O2 bound/O2 capacity ) x 100
why is there a sigmoid shape when Hb becomes saturated
- everytime O2 is bound, Hb slightly changes its shape so it’s easier for another O2 molecules to bind too
- the curve levels off because its almost saturated
what’s P50 on Hb sigmoid graph
at a partial pressure of O2 where Hb is 50% saturated
-measure of affinity of Hb for O2
increased factors that decrease affinity or PO50
-PCO2
[H+]
-2,3-DPG
-temperature
- the sigmoid curve will move to the right - this is the bohr’s effect
- if these factors are decreased, the affinity increases and move to the right
explain why bohr’s effect occurs
-binding of C02 and H+ to the alpha and beta chains changes the shape of Hb and the affinit of haem group for O2
why is bohr effect useful
- binding of CO2 and H+ helps to unload O2 to the tissues as the affinity decreases
- 02 delivery matches tissue metabolic needs
what is 2,3-DPG
side product produced in glycolysis
-binds to beta chains and increases O2 delivery and decreasing co2 to the tissues in alkalosis and chromic hyproxia
why is carbonnic anhydrase used
used to speed up the reaction of forming carbonic acid
-protected from degradation if present in the RBCS
pathways where CO2 can be used in the plasma
- in solution for partial pressure
- bind to a protein as a carboxyl group
- forms carbonic acid so HCO3 and H ions are formed too
pathways where CO2 can be used in the RBC
- in solution for partial pressure
- bind to a deocy -Hb protein as a carboxyl group
- forms carbonic acid so HCO3 and H ions are formed too
how does HCO3 get transported out of the RBC to the plasma
through HCO3-CL-exchanger
what stores CO2
HCO3
what is haldane effect
- at lower O2 saturation, more CO2 can bind to be removed from the tissues
- at higher saturation, More CO2 released to the tissues
haldane effect vs bohr effect
Haldane effect is what happens to pH and CO2 binding because of oxygen, and Bohr effect is what happens to oxygen binding because of CO2 and lower pH.
