**4.5 Transport of gases in the blood**

Question 1

What is the structure of haemoglobin?

Answer 1

• Globular, water soluble.
• 4 polypeptide chains, each carrying a haem group.

Question 1

Where is haemoglobin found and what is its role?

Answer 1

• In RBCs.
• Oxygen molecules bind to haem groups + carried to respiring tissue.

Question 2

How does the partial pressure of oxygen affect oxygen-haemoglobin binding?

Answer 2

• Partial pressure of O2 increase - affinity of haemoglobin for O2 also increases ∴ O2 binds tightly.
• When partial pressure is low, O2 released from haemoglobin.

Question 3

What is the Bohr effect?

Answer 3

• Partial pressure of CO2 increases + conditions become acidic causing haemoglobin to change shape.
• Affinity of haemoglobin for oxygen ∴ decreases —> O2 released from haemoglobin.

Question 4

What do oxyhaemoglobin curves show?

Answer 4

• Saturation of haemoglobin with O2 (%) against partial pressure of O2 (kPa).

Question 5

What does it mean if an oxyhaemoglobin is further to the left?

Answer 5

• Haemoglobin has a higher affinity for O2.

Question 6

How does the Bohr effect alter the position of an oxyhaemoglobin dissociation curve?

Answer 6

• Haemoglobin’s affinity for O2 has decreased ∴ curve shifts to right.

Question 7

What are 3 ways in which myoglobin differs from haemoglobin?

Answer 7

• Only has one haem group.
• Has very high affinity for O2 even at low partial pressures.
• Found in muscle cells of mammals w/ high metabolic demands.

Question 8

How does foetal haemoglobin differ from adult haemoglobin?

Answer 8

• Partial pressure of O2 is low by the time it reaches the foetus ∴ foetal haemoglobin has higher affinity for O2 than adult.
• ∴ both mother + child’s O2 needs can be met.

Question 9

What is positive cooperativity?

Answer 9

• When O2 molecules bind to haemoglobin, cause conformational change ∴ increase O2 affinity ∴ further molecules bind more easily.