Oxygen in the Blood

Question 1

Describe things that will shift the oxygen dissociation curve of Hb to the left. (4)

Answer 1

Decreased temperature
Decreased CO2
Increased pH
Decreased 2,3-BPG

Question 2

Describe the things that will shift the oxygen dissociation curve of Hb to the right (Bohr). (4)

Answer 2

Increased temperature
Increased CO2
Decreased pH
Increased 2,3-BPG

Question 3

Describe the differences between hypoxia and hypoxaemia (2)

Answer 3

Hypoxia - low oxygen levels at tissues

Hypoxaemia - low oxygen levels in the blood.

Question 4

Describe the oxygen content of the blood in mmol/l. (3)

Answer 4

Alveolar p(O2) is 13kPa and Hb is saturated. 
Hb is normally about 2.2, and each Hb has 4 oxygens, so oxygen content is 8.8mmol/l.

Question 5

Explain the causes of cyanosis. (3)

Answer 5

Unsaturated Hb.
In peripheries - oxygen has run out by the time it gets there because blood is moving slowly.
Central - blood is being pumped out of the heart already deoxygenated.

Question 6

Explain why anaemia presents with normal p(O2). (2)

Answer 6

Because the amount of haemoglobin saturated with oxygen is the same, there is just less haemoglobin so oxygen content is lower.

Question 7

Describe ways of assessing oxygenation. (3)

Answer 7

Pulse oximeter - detects difference in light absorption between oxygenated and deoxygenated blood. Doesn’t check Hb levels
ABG - can assess Hb but is invasive.