7.2 Transport of oxygen by haemoglobin

Question 1

what is the oxygen dissociation curve

Answer 1

the relationship between the saturation of haemoglobin with oxygen and the partial pressure of oxygen

Question 2

describe the shape of the oxyhaemoglobin dissociation curve

Answer 2

shallow curve
curve becomes steeper
curve almost plateaus

Question 3

explain the shape of the oxyhaemoglobin dissociation curve

Answer 3

shallow - low affinity for oxygen at lower partial pressures
steep - affinity for oxygen increases
almost plateaus - high affinity for oxygen at higher partial pressures

Question 4

explain how the binding of O2 affects the shape of haemoglobin

Answer 4

hard for 1st O2 to bind as haem groups are in the middle
2nd and 3rd bind easily due to conformational change
hard for 4th as it has to bind to the last haem group

Question 5

define the bohr effect

Answer 5

haemoglobin has reduced affinity for O2 in the presence of CO2
meaning it can load oxygen less readily and unloads more easily

Question 6

explain the bohr effect

Answer 6

dissolved CO2 lowers pH (is acidic)
- causing haemoglobin to change shape
there’s little CO2 at gas exchange surfaces
- affinity for O2 is high
there’s a high conc of CO2 as respiring tissues
- low affinity for O2

Question 7

how is haemoglobin adapted in animals at low partial pressures of O2? (curve)

Answer 7

• high affinity for O2
• curve moves to the left
• allows fully saturated haemoglobin at low partial pressures of O2

Question 8

how is haemoglobin adapted in animals at high partial pressures of O2? (curve)

Answer 8

• low affinity for O2
• curve moves to the right