Haemoglobin + Bohr shift

The dissociation of oxygen for haemoglobin + how partial pressure affects it

• Haemoglobin can carry 4 molecules of oxygen

• The amount that associates depends on the partial pressure of oxygen

• It readily associates when the pO2 is high i.e. at rest alveoli po@ 105mmHg

• Therefore the blood leading the alveoli is 98% saturated with oxygen

• This relationship is shown in the oxyhaemoglobin dissociation curve

 

When PO2 is high…

haemoglobin has a high affinity for oxygen

Haemoglobin saturation during exercise

during exercise pO2 in the muscles drops to 5 and the saturation of haemoglobin drops to 25%. 75% of oxygen is released to the muscle cells in order to supply the increased demand of oxygen required for respiration.

Three other effects of exercise which increase the dissociation of oxygen from haemoglonion

1. Increase in temperature

2. Increase in CO2

3. Increases production of lactic acid and carbonic acid (lowers pH)

What is the Bohr shift?

Oxygen disassociation curve shift to the right

MC COAT

M = muscle activity increases

C = curve shifts to the right

 

C = carbon dioxide increases

O = oxygen decreases

A = acidity increases (lower pH)

T = temperature increases

Graph of Bohr shift

Why is warm up important?

Triggers Bohr shift

Why is recovery important?

• Shifts curve back to the left

• Returns haemoglobin saturation with oxygen to its original relationship

• Flushes waste