6. Transport of Carbon Dioxide in Blood and Body Fluids

Question 1

How is CO2 is formed?

Answer 1

As O2 is used for cellular metabolism

Question 2

order the steps CO2 transport from the tissue to Lungs

1. Increase in intracellular PCO2
2. pressure gradient between cells and interstitial fluid builds up
3. pressure gradient between interstitial fluid and tissue capillaries
4. increase interstitial fluid PCO2
5. CO2 diffusion from cells into interstitial fluid
6. diffusion of CO2 into capillaries

Answer 2

1. ncrease in intracellular PCO2
2. pressure gradient between cells and interstitial fluid builds up
3. . CO2 diffusion from cells into interstitial fluid
4. increase interstitial fluid PCO2
5. pressure gradient between interstitial fluid and tissue capillaries
6. diffusion of CO2 into capillaries

Question 3

PCO2 is ______ in pulmonary capillaries than in alveoli (________) –> CO2 diffuses from capillaries into ______ where it gets expired

Answer 3

Higher
Pressure gradient
alveoli

Question 4

Notice that at each point in gas transport chain, CO2 diffuses in direction _______ to O2

Answer 4

Opposite

Question 5

Major differance between CO2 and O?

Answer 5

CO2 can diffuse ~ 20x faster than O2

Question 6

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

Answer 6

much less

Question 7

What are the 3 forms of CO2 transport in blood?

Answer 7

1. Dissolved in plasma (7%)
2. In the form of bicarbonate ion (70%)
3. Bound with Hb and plasma proteins in RBC (23%)

Question 8

Combination of CO2 and Hb is ____ and _____

Answer 8

loose

reversible

Question 9

The bond between CO2 and Hb depends on ______. This aids in diffusion how?

Answer 9

PCO2

CO2 is easily released into alveoli since PCO2 is lower than in pulmonary capillaries

Question 10

Transport via Hb and plasma proteins in RBC. _______ amount of CO2 also reacts with plasma proteins

Answer 10

Small

Question 11

As gas pressure of CO2 increases CO2 ( vol/percent) Increase or decreases?

Answer 11

Increase

Question 12

Is it safe for the blood PCO2 to have a wide range or a narrow range?

Answer 12

Very Narrow

Question 13

As blood passes through the lungs, PO2 _______ and O2 binds with Hb. Causing Hb to become a stronger _____?

Answer 13

increases

Acide

Question 14

The increased acidity due to O2 binding to Hb causes the following two effects?

Answer 14

1. CO2 attached to Hb (carbaminohemoglobin) is displaced, and free CO2 diffuses through pulmonary capillary membrane into alveoli
2. Also promotes H+ dissociation from Hb

Question 15

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?

Answer 15

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

Question 16

Respiratory exchange ratio ( What is the eqn?)

Answer 16

Rate of CO2 output/ Rate of O2 Uptake

VCO2/ VO2

(V-A) CO2 diff/ (A-V) O2 difference

Question 17

What is the PCO2 inside the cell?

Answer 17

46 mmHg

Question 18

What is the PCO2 In tissue interstitial fluid?

Answer 18

45 mmHg

Question 19

PaCO2?

Answer 19

40 mmHg

Question 20

PvCO2

Answer 20

45 mmHg

Question 21

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?

Answer 21

Small : 2mmHg

Whereas O2 has a large difference delta PO2 = 64 mmHg

Question 22

Is the combination of CO2 with Hb loose and reversible as well?

Answer 22

Yes,

Bond depends on PCO2, so CO2 is easily released into alveoli since PCO2 is lower than in pulmonary capillaries

Question 23

Is there a high range for PCO2 in the blood?

Answer 23

No. Very narrow range.
PaCO2 = 40 mmHg
PVCO2 = 45 ~ 46 mmHg

Question 24

What is the Haldane effect?

Answer 24

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

Question 25

The Haldane effect promotes H+ dissociation from Hb. How does this result in the release of more CO2?

Answer 25

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

Question 26

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?

Answer 26

True (….)

Question 27

Does the diffusiojn of O2 affect them amount CO2 released?

Answer 27

Yes. At PO2 = 40 There is more CO2 release in the blood in comparison to PO2=100 for the same PCO2.

Question 28

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?

Answer 28

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)

Question 29

What happens to the RER If a person is on a normal diet and consumes average amount of carbohydrates, fats, and proteins for energy

Answer 29

= 4/5 = 0.80 (~ 0.82)

{CO2 difference = 4 vol % , O2 difference = 5 vol % …. R= 4/5 }

Question 30

What happens to the RER If a person consumes exclusively carbohydrates for energy?

Answer 30

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 }

Question 31

What happens to the RER If a person If a person is consuming exclusively fats for energy?

Answer 31

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

Question 32

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

Answer 32

R = 5.8

• CvCO2-CaCO2)/CaO2-CvO2 ;
• (54 vol % - 48 vol % ) / ( 19 vol % - 13 vol %)