Question

(A) Hemoglobin is 50% saturated (P50) at 20 torr, which is approximately equal to the partial pressure of O2 in muscle. The partial pressure of O2 in the lungs is 100 torr. If the Hill coefficient nh = 3, calculate how efficient hemoglobin is at O2 delivery. Express your answer as the difference between factional O2 binding in the lungs and fractional O2 binding in muscle (qlungs – qmuscle). (B) How would the efficiency of O2 delivery change if hemoglobin were not cooperative (i.e. if nh =1)?

Answer 1

Answer:

Explanation:

Given that:

P₅₀ = 20 torr in muscle

The partial pressure of O2 in lungs Po₂ = 100 torr

The hill coefficient $n_h$ = 3

According to the Hill coefficient;

$\dfrac{\Upsilon}{1-\Upsilon}= (\dfrac{PO_2}{P_{50}})^n$

here;

$\Upsilon$ = fraction of haemoglobin monomers

$\dfrac{\Upsilon}{1-\Upsilon}= (\dfrac{100}{20})^3$

$\dfrac{\Upsilon}{1-\Upsilon}$ = 125 θ lungs

However for θ muscle :

$(\dfrac{PO_2}{P_{50}})^n=( \dfrac{20}{20})^3$

= 125 (θ lungs) - 1 (θ muscle)

= 124

B.

if nh =1

$\mathtt {\theta \ lungs} = \dfrac{\Upsilon}{1-\Upsilon}= (\dfrac{100}{20})^1$

$\mathtt {\theta \ lungs} =5$

$\mathtt {\theta \ muscle} = \dfrac{20}{20}^1$

(θ muscle) = 1

(θ lungs) - (θ muscle) = 5 - 1

(θ lungs) - (θ muscle) = 4