Co2 in blood Flashcards
Carbon dioxide is an essential part of the buffer systems which controls the pH of extra cellular fluid.
where can ufind Co2?
Although CO2 is transported in venous blood,
there is a substantial amount of CO2 in arterial blood which has a vital role in acid base balance!
COOOL
when carbon Dioxide is in Plasma it may form hydrogen ions and (bicarbonate) ions.
But The reaction is slow…why?
The reaction is slow because there is little carbonic anhydrase in the plasma.
how does Co2 determine the pH of plasma, and therefore extra cellular fluid?
it depends on the extent of dissociation,
he equilibrium is driven towards dissociation by rises in dissolved CO2.
Remember…..The amount of CO2 which dissolves is directly proportional to pCO2.
ok
how is bicarbonate formed?
come from a reaction of CO2 in the rbc
pH therefore _____ if pCO2 rises
pH therefore_____ if [HCO3-] rises
pH therefore falls if pCO2 rises
pH therefore rises if [HCO3-] rises
Henderson - Hasselbalch equation
In plasma the ratio of [HCO3-] to dissolved CO2 is _____
20:1
In body fluids with few or no other buffer systems (e.g. plasma alone, CSF),
how is the concentration of HCO3, affected by pCo2?
it is not affected by changes in pCO2, and remains effectively constant over all physiological values of pCO2 unless changed by other mechanisms.
Describe Carbon Dioxide reaction in the Red Cell.
function of Carbonic Anahydrase?
accelerates the time Co2 reacts with water!
what do the H ions produced in the reaction do?
binds to globin chains of Hb, this decreases the affinity of Hb to Oxygen! O2 is released!
BOHR shift TO RIGHT
facilitates O2 to be delivered to tissues!
The hydrogen ions bound to Haemoglobin has a large buffering capacity,
IT is enhanced further when it is Hb is __________
de-oxygenated.
The reaction is therefore ‘drawn’ towards production of HCO3-. The amount produced depends primarily upon the buffering effects of haemoglobin, with only minor effects of changes in pCO2.
what happens to the HCO 3- formed in the RBC
HCO3 concentratio in RBC is MORE than in plsma>> so it moves out!
BUTT.. if too much HCO3 leaves, it’ll make the inside of RBC positive!
we dont want all this change in charges and shit happening…..
so HCO3- is exchanged with Cl-!
why r RBC slighty swollen in venous side?
bc when Cl was entering the cell and HCO#- was leaving,
CL coming in causes water to follow it,,, causing a slight swelling!
The pH of the body fluids is therefore determined by the relationship between:
- the amount of CO2 dissolved in plasma, and
- the amount of HCO3- formed from CO2 in the RBC by a reaction involving Hb
where is [HCO3-] in plasma also controlled?
is also controlled by the kidney
The critical feature is that so long as there is 20x as much HCO 3- as dissolved CO2 in plasma then the pH will be 7.4.
got it
how is Co2 transported to lungs? it what forms?
The amount of CO2 transported by the blood is determined by what?
difference between the venous and arterial CO2 content.
Does CO2 travel from tissues to lungs as carbamino compounds more or as dissolved CO<strong>2</strong> more ?
as carbaaminno more!
Describe the function of carbamino compounds.
State the factors influencing the Hco3 concentration of plasma.
what happens when RBC reach lungs?
List in order methods of Co2 transport from greatest to least
80% as (bicarbonate).
12% as carbamino compounds
8% of transported CO2 travels as dissolved CO2,
difference in Co2 and O2 in blood
and effects of hyperventilation
alaa look at workbook noted for this session ok?
