oxygen dissociation and the bohr effect lesson 2

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Identify with reasons which curve represents: a) Normal adult haemoglobin b) myoglobin c) fetal haemoglobin d) Llama haemoglobin (adapted to hypoxic conditions) also: show the curve at high pCO2

(l) describe the role of haemoglobin in carrying oxygen and carbon dioxide;

(m) describe and explain the significance of the dissociation curves of adult

oxyhaemoglobin at different carbon dioxide

levels (the Bohr effect);

(n) explain the significance of the different

affinities of fetal haemoglobin and adult

haemoglobin for oxygen.

Exchange and transport

Carbon dioxide transport

Exchange and transport

Carbon dioxide transportWe are learning to…

Describe the role of haemoglobin in carrying carbon dioxide.Describe and explain the significance of the dissociation curves of adult oxyhaemoglobin at different carbon dioxide levels (the

Bohr effect).

You will be able to…

Explain how carbon dioxide in transported from respiring cells to the alveoli

Write a word equation for the key reactions

Carbon dioxide transport

Carbon dioxide transport• 85% is transported in the plasma as dissociated

hydrogen carbonate.H20 + CO2 ↔ H2CO3 ↔ H+ + HCO3-• 15% is carried by the haemoglobin (Hb) as

haemoglobinic acidHbNH2 + CO2 ↔ HbNHCO2 - + H+

• Carriage of carbon dioxide by the plasma is catalysed by carbonic anhydrase. Increased hydrogen ion concentration causes blood pH to drop so more oxygen is released from the haemoglobin.

• Chloride shift balances the movement of HCO3- ions into plasma

Buffers in the blood• Varying the concentration of gases in the blood

affects the pH, and can cause the blood to become to acidic (ACIDOSIS) or too alkaline (ALKALOSIS).

• Blood pH should be maintained at 7.35 – 7.45• Acidosis is caused by excess carbon dioxide, and

alkalosis by a lack of hydrogen ions.• Potassium ions bind to the Hb so it can soak up

the H+

• KHbO2 KHb + O2• KHb+ H+ + HCO3- KHCO3 + HHb

Haemoglobinic acid