7.1 - Haemoglobin

Question 1

how does conc of CO2 affect haemoglobin saturation?

Answer 1

• HigherpCO2at respiring tissues causes haemoglobin to release oxygen.
• This is because of the Bohr effect, which is the decreased affinity for oxygen in haemoglobin when carbon dioxide is present.
• This means the oxygen saturation of haemoglobin is lower for a givenpO2whenpCO2 is higher.

This is needed because the active tissues that produce carbon dioxide require a lot of oxygen from blood. The Bohr effect shifts the oxygen dissociation curve to the right

Question 2

What is the Bohr Shift?

Answer 2

Haemoglobin also has a lower affinity for oxygen at higher partical pressures of CO2 (pCO2)

Question 3

Fetal vs adult haemoglobin

Answer 3

• The fetus needs to obtain oxygen from the mother’s blood.
• The fetal haemoglobin therefore has a higher oxygen affinity than the adult haemoglobin found in the mother’s blood.
• This allows the oxygen to dissociate from the mother’s haemoglobin, and bind with haemoglobin in the fetal blood.
• This ensures that the fetus gets enough oxygen to survive while it develops.
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Question 4

Co-operative binding of oxygen

Answer 4

When haemoglobin binds with one oxygen, it changes the tertiary structure shape so it becomes easier to bind another oxygen as another binding site is uncovered
When haemoglobin is mostly saturated with oxygen, it is harder for more oxygen to bind.

Question 5

What does a higher partial pressure vs a lower partial pressure of oxygen mean?

Answer 5

• HigherpO2- Haemoglobin has a high affinity for oxygen and binds with it (e.g. in the lungs).
• LowerpO2 - Haemoglobin has a low affinity for oxygen and releases it (e.g. at respiring body cells).

Question 6

What does haemoglobin saturation with oxygen depend upon?

Answer 6

the conc/partial pressure of oxygen (kPa)

Question 7

How does oxygen get transported via haemoglobin to the respiring tissues?

Answer 7

1. Oxyhaemoglobin can be transported via blood to respiring body tissues.
2. At body cells, oxygen dissociates from haemoglobin.

Question 8

How many oxygen molecules can haemoglobin carry?

Answer 8

one per haem group - 4 oxygen molecules

Question 9

what does oxygen bind to in the lungs within the capillaries?

Answer 9

binds to iron in haem groups forming oxyhaemoglobin

Question 10

how many haem groups does haemoglobin have?

Answer 10

4

Question 11

How is oxygen transported to the body cells?

Answer 11

via blood which has RBCS which contain haemoglobin