Physiology: O2 delivery & haemoglobin

Question 1

what does O2 delivery rely on

Answer 1

O2 content of arterial blood and the cardiac output(CO)

Question 2

what is O2 content of arterial blood determined by

Answer 2

haemoglobin(Hb) conc. and the saturation of Hb with O2

Question 3

what can O2 delivery to the tissues be impaired by (4)

Answer 3

decrease in partial pressure of inspired O2
respiratory distress
heart failure
anaemia

Question 4

how does respiratory distress impair O2 delivery

Answer 4

can decrease arterial Po2 and therefore decrease Hb saturation with O2 and the O2 content of blood

Question 5

how does heart failure impair O2 delivery

Answer 5

decreases cardiac output(CO)

Question 6

how does anaemia impair O2 delivery

Answer 6

decreases Hb conc., and therefore O2 content of blood

Question 7

describe what is meant by co-operativity of Hb molecules

Answer 7

binding of one O2 to Hb increases the affinity of Hb for O2 at the other haem groups

Question 8

how does HbF(foetal haemoglobin) differ from adult Hb

Answer 8

different structure and has higher affinity for O2

allows O2 transfer from mother to foetus even when Po2 low

Question 9

how is the O2-Hb dissociation curve of HbF different to HbA

Answer 9

shifted to the left

Question 10

how is the O2-Hb dissociation curve different to the O2-myoglobin dissocation curve

Answer 10

O2-Hb = sigmoid shape(S shape)
O2-myoglobin = hyperbolic shape(upside down L)

Question 11

How does the structure of HbF differ to that of HbA

Answer 11

HbF = 2 alpha sub units, 2 gamma sub units
HbA = 2 alpha sub units, 2 beta sub units