Lecture #17 - O2 and CO2 transport

Question 1

What are the two forms in which oxygen is carried around in the blood?

Answer 1

-

Question 2

How many ml per L of blood can each mmHg PO2 carry if rely just on dissolved oxygen?

Answer 2

-

Question 3

Hb:

1. O2 forms what kind of combination with Hb to give oxyhaemoglobin?
2. Binding depends on what?
3. What is O2 saturation of Hb? What does it vary with?
4. What is P50? What value is it?
5. PO2/saturation relationship is what?

Answer 3

-

Question 4

Sigmoidal curve:

1. Upper flat part of curve - moderate changes around the normal value (~100mmHg) have only small effects on the ____ ______ and therefore the ____ of O2 carried by ____ _____ (i.e. some ______ capacity)
2. Steep part of curve at lower PO2 - helps with ____ of Hb in _____ and ______ of O2 in the _____ (small changes in PO2 result in large changes in _____ of O2 bound to Hb)

Answer 4

-

Question 5

1. What is O2 capacity?
2. How many grams of Hb per litre does normal blood carry?
3. One gram of Hb can carry how many ml of O2?
4. O2 capacity = ? (calculate it)

Answer 5

-

Question 6

1. What is the O2 content?
2. What’s the formula for the O2 content? Units for everything?
3. So each litre of blood gives up how many ml of O2?
4. a-v difference = amount of O2 _____ by tissues

Answer 6

-

Question 7

Exercise

1. If more oxygen is extracted, what does it say about a-v? How is it possible (relate to saturation curve)
2. So does Hb concentration change the saturation curve?
3. O2 content is dependent on what? So relate to anaemia
4. At 20mmHg, what percentage will Hb be saturated?

Answer 7

3. Anaemic people have less Hb content because the Hb amount is reduced. They can’t extract 150ml/L if are only carrying 100ml/L

Question 8

Carbon monoxide

1. Combines with what to form what? - Blocks what?
2. How much higher/lower is the affinity of CO than O2?
3. Small amounts of CO can tie up ____ ____ of Hb in blood - reduced O2 ____
4. What does it also do to the curve? Curves don’t change with change in _____ so CO must change the _____ of Hb (i.e. make it difficult to _____ O2)

Answer 8

-

Question 9

1. Left shift means more ______ of O2 in the _____
   - Oxygen affinity up or down?
   - P50 up or down?
   - caused by…4 things
2. Right shift means more ______ of O2 in ______
   - Oxygen affinity up or down?
   - P50 up or down?
   - caused by….4 things

Answer 9

-

Question 10

A right shift of the curve could be due to ______ effect

Answer 10

-

Question 11

Bohr effect

1. If a right right shift in curve, what 4 things increase/decrease?
2. For particular PO2 will have lower what two things?
   - Hb “____ ___” O2
3. In this case, the effect improves _____ of O2 in Hb.

Answer 11

-

Question 12

Bohr effect

1. If a left shift in curve, due to what? E.g.
2. For particular PO2 will have higher what two things?
   - Hb “___ __” O2
3. So, Bohr effect improves both……

Answer 12

-

Question 13

BPG

1. By product of what?
2. Increase with what 4 things? i.e. a lot of _____ metabolism
3. Helps deliver O2 to tissue due to _____ shift of curve - which allows more O2 to be ____ from Hb at a particular PO2 = increase/decrease unloading?

Answer 13

-

Question 14

CO2 can be transported in three forms - what are they and what are their percentages. Explain the 2nd and 3rd examples - how does it work?

Binding of CO2 is easier when Hb is/is not bound to O2?

Answer 14

-