6. Transport of Carbon Dioxide in Blood and Body Fluids Flashcards
How is CO2 is formed?
As O2 is used for cellular metabolism
order the steps CO2 transport from the tissue to Lungs
- Increase in intracellular PCO2
- pressure gradient between cells and interstitial fluid builds up
- pressure gradient between interstitial fluid and tissue capillaries
- increase interstitial fluid PCO2
- CO2 diffusion from cells into interstitial fluid
- diffusion of CO2 into capillaries
- ncrease in intracellular PCO2
- pressure gradient between cells and interstitial fluid builds up
- . CO2 diffusion from cells into interstitial fluid
- increase interstitial fluid PCO2
- pressure gradient between interstitial fluid and tissue capillaries
- diffusion of CO2 into capillaries
PCO2 is ______ in pulmonary capillaries than in alveoli (________) –> CO2 diffuses from capillaries into ______ where it gets expired
Higher
Pressure gradient
alveoli
Notice that at each point in gas transport chain, CO2 diffuses in direction _______ to O2
Opposite
Major differance between CO2 and O?
CO2 can diffuse ~ 20x faster than O2
CO2 can diffuse ~ 20x faster than O2, Means that pressure gradients required to cause CO2 diffusion are _______ than gradients required to lead to O2 diffusion
much less
What are the 3 forms of CO2 transport in blood?
- Dissolved in plasma (7%)
- In the form of bicarbonate ion (70%)
- Bound with Hb and plasma proteins in RBC (23%)
Combination of CO2 and Hb is ____ and _____
loose
reversible
The bond between CO2 and Hb depends on ______. This aids in diffusion how?
PCO2
CO2 is easily released into alveoli since PCO2 is lower than in pulmonary capillaries
Transport via Hb and plasma proteins in RBC. _______ amount of CO2 also reacts with plasma proteins
Small
As gas pressure of CO2 increases CO2 ( vol/percent) Increase or decreases?
Increase
Is it safe for the blood PCO2 to have a wide range or a narrow range?
Very Narrow
As blood passes through the lungs, PO2 _______ and O2 binds with Hb. Causing Hb to become a stronger _____?
increases
Acide
The increased acidity due to O2 binding to Hb causes the following two effects?
- CO2 attached to Hb (carbaminohemoglobin) is displaced, and free CO2 diffuses through pulmonary capillary membrane into alveoli
- Also promotes H+ dissociation from Hb
Increased acidity of Hb due to O2, promotes H+ dissociation from Hb, does this have an affect on CO2 diffusion from the blood into the alveoli or the other way around? How?
Yes, from blood to alveoli
excess H+ binds with the bicarbonate ion HCO3- to form carbonic acid H2CO3 –> H2CO3 dissociates into H2O and CO2 –> CO2 is released from blood into alveoli and, finally, into air
Respiratory exchange ratio ( What is the eqn?)
Rate of CO2 output/ Rate of O2 Uptake
VCO2/ VO2
(V-A) CO2 diff/ (A-V) O2 difference
What is the PCO2 inside the cell?
46 mmHg
What is the PCO2 In tissue interstitial fluid?
45 mmHg
PaCO2?
40 mmHg
PvCO2
45 mmHg
Is the difference in PCO2 from the start of the pulmonary capillary to that of the alveolar air small or large? How about that of O2?
Small : 2mmHg
Whereas O2 has a large difference delta PO2 = 64 mmHg
Is the combination of CO2 with Hb loose and reversible as well?
Yes,
Bond depends on PCO2, so CO2 is easily released into alveoli since PCO2 is lower than in pulmonary capillaries
Is there a high range for PCO2 in the blood?
No. Very narrow range.
PaCO2 = 40 mmHg
PVCO2 = 45 ~ 46 mmHg
What is the Haldane effect?
As blood passes through the lungs, PO2 increases and O2 binds with Hb, Hb becomes a stronger acid
- -> Hb now releases CO2
- -> Promotes H+ dissociation from Hb: CO2 is released from blood into alveoli and, finally, into air
The Haldane effect promotes H+ dissociation from Hb. How does this result in the release of more CO2?
The excess H+ binds with the bicarbonate ion HCO3- to form carbonic acid H2CO3 –> H2CO3 dissociates into H2O and CO2 –> CO2 is released from blood into alveoli and, finally, into air
True or false? Bohr effect is Combined affect of blood PCO2 and Blood pH on how much O2 would be release from the blood (O2 hemaglobin binding), this is opposite of the Haldane effect?
True (….)
Does the diffusiojn of O2 affect them amount CO2 released?
Yes. At PO2 = 40 There is more CO2 release in the blood in comparison to PO2=100 for the same PCO2.
At PO2 = 40 There is more CO2 release in the blood in comparison to PO2=100 for the same PCO2. Why is this important? And this is part of which effect?
This is important so that gas exchange of the two gasses don’t occur at the time. PO2= ~100 at the arterial end of the capillaries whereas PO2= ~40 near the venous. Thus as O2 difusiuons levels off CO diffusion starts occur ( Related to Filtration/absorption in away)
What happens to the RER If a person is on a normal diet and consumes average amount of carbohydrates, fats, and proteins for energy
= 4/5 = 0.80 (~ 0.82)
{CO2 difference = 4 vol % , O2 difference = 5 vol % …. R= 4/5 }
What happens to the RER If a person consumes exclusively carbohydrates for energy?
R is almost equal to 1
{ Because when O2 is metabolized with carbohydrates, each molecule of O2 consumed will form one molecule of CO2:
C6H12O6 + 6 O2 –> 6 CO2 + 6 H2O -> 6/6 =1 }
What happens to the RER If a person If a person is consuming exclusively fats for energy?
R =0.7
{ Because when O2 interacts with fats, large amounts of O2 will bind with hydrogen to form water H2O instead of CO2:
C16H32O2 + 23 O2 –> 16 CO2 + 16 H2O
=> 16CO2/ 23O2 = 0.7
A older male visits your laboratory with the following data summary: CaO2 = 19 vol % CaCO2 = 48 vol % PaO2 = 95 mmHg PaCO2 = 40 mmHg CvO2 = 13 vol % CvCO2 = 54 vol % PvO2 = 35 mmHg PvCO2 = 50 mmHg
Calculate R
R = 5.8
- CvCO2-CaCO2)/CaO2-CvO2 ;
- (54 vol % - 48 vol % ) / ( 19 vol % - 13 vol %)
