Haemoglobin and Gas Transport

Question 1

How much oxygen will dissolve in 1l of plasma?

Answer 1

3ml

Question 2

What does the partial pressure tell us?

Answer 2

• The amount of oxygen in solution- not bound to Haem.

- The force pushing the oxygen out of the alveoli and into the haemoglobin.

Question 3

What is the partial pressure of oxygen in alveoli?

Answer 3

100mmHg

Question 4

How much oxygen can we transport with Haemoglobin?

Answer 4

200ml/l

So with each CO = 200 x 5 = 1000ml per minute

Question 5

How much oxygen do our cells need?

Answer 5

250ml of Oxygen per minute.

Question 6

Define Co-operative binding

Answer 6

When one molecule of O2 is bound it increases the affinity of the Haemoglobin to other O2 molecules.

Question 7

Does the Partial pressure change?

Answer 7

No

• the high affinity of Haem pulls O2 out of solution
• this maintains the partial pressure gradient
• meaning o2 keeps entering the blood.

Question 8

Name the main type of haemoglobin

Answer 8

Adult Haem= HbA

Makes up 92%

Question 9

What are the other forms of Hb?

Answer 9

HbF = Foetal Haem= higher affinity than HbA
HbA2 (delta instead of beta)
Myoglobin- found in muscle cells.
HbA1 (a/b/c) - show the exposure to glucose

Question 10

At 40mmHg what is the Haemoglobin saturation?

Answer 10

75%

Below 40mmHg = death zone.

Question 11

Why is this important?

Answer 11

It means that even in places with a lower partial pressure of O2 the haemoglobin can still supply cells.

Question 12

What effect does Anaemia have on Partial Pressure?

Answer 12

None- there is lower levels of Haemoglobin

But partial pressure only refers to the plasma.

Question 13

What is the effect of lowering the affinity of Haemoglobin?

Answer 13

• More O2 is offloaded to tissues

- The curve shifts to the right (need higher PaO2 to achieve same result)

Question 14

What would lower the affinity of Hb?

Answer 14

• High temperature
• High PaCo2
• Low pH
• Higher 2,3-DPG

Question 15

Why is Carbon Monoxide a problem?

Answer 15

It has an affinity which is 250x higher than O2

• Symptoms- cherry red skin, hypoxia, anaemia, nausea.
• treat with 100% O2

Question 16

Name 5 types of Hypoxia

Answer 16

1) Hypoxic- not enough air (low ventilation)
2) Ischaemic (poor blood supply)
3) Anaemic (not enough oxygen carried in blood)
4) Histotoxic (poisoning- CO or cyanide)
5) Metabolic (exercise- demand exceeds supply)