Module 3.3 - Biomass Transport III (Oxygen-Hb Reactions and Oxygen Exchange in Lung Caps)

Question 1

Over what percentage of blood is bound to Hb?

Answer 1

99%

Question 2

What are the 2 sources of O2 in the blood from which O2 can move?

Answer 2

• O2 dissolved in cytoplasm of RBC
• O2 din RBC bound to hemoglobin

Question 3

Assumptions applied when modelling oxygenation and dioxygenation of RBCs (or rate of O2 transfer) (5)

Answer 3

• Cell interior is well-mixed
• Oxygen solubility in cytoplasm is the same as in the plasma (phi_A,12 = phi_A,21 = 1)
• Plasma [O2] remains constant
• Oxyhemoglobin inside RBC is initially at equil’m w/ cellular O@
• Oxyhemoglobin within cell exists as only Hb(O2)4

Question 4

How many oxygen molecules can bind to one hemog. molecule?

Answer 4

4

Question 5

Why does Henry’s Law apply to represent [O2] in blood as a partial pressure?

Answer 5

Oxygen is a small gas in a liquid solvent. Henry’s Law states the partial pressure of the gas inside the liquid is equal to the vapour pressure of the gas at the liquid’s surface.

Question 6

What is the bad assumption made when deriving the rate of oxygen uptake/release?

Answer 6

The C_HbO2 vs. P_O2 curve yields a constant slope (to give m = S_HbO2/P_O2), but the curve is actually non-linear

Question 7

What is the saturation constant of oxyhem.?

Answer 7

Fraction of hemog. molecules with 4 O2 bound to it out of all hemog. molecules

Question 8

T/F: The constant slope assumption is largely inaccurate to model pulmonary capillary partial pressure of O2

Answer 8

True