1/ The size of the cell is mainly depends on the availability of O2.
2/ Simple diffusion is not enough for O2 to reach the center of the cell.
3/ The partial pressure of O2 is dropped sharply when the O2 transports from the bulk toward the center. To improve this mechanism and decrease the reduction of O2, the convection works with diffusion to have sufficient amount of O2 that can reach the cell beyond a critical value ( Below can cause the death of the cell).
4/The addition of convection decreases the resistance to diffusion Why? because most of nutrients, blood, and O2 move in the same direction.
5/Naturally, that happens in our bodies by: Circulatory system(shorter distances), and Hemoglobin( overcome the low solubility of O2 in water).
6/The concentration of O2 can be determine using Henry's constant and pO2.
7/In most of the time (if not always), the consumption of O2 in our bodies is constant= Vmax.
8/Hemoglobin consists of 4 chains (2 alpha, 2 beta) which are held together by non covalent attractions.
9/ Capacity of O2 in hemoglobin is 4 due to 4 heme groups where iron (the reason of the red color of the blood) can bond with 6 bond, 4 with N and 2 with O2.
10/ As the concentration of dissolved O2 increases, the amount of O2 that can bind with HB increases too until it reaches 4 ,(Y=1), the increase of pO2 or Co2 is useless.
11/ The consumption and generation of O2 and HB happen in equilibrium by the backward and forward reactions, respectively.
12/ H+, CO2, PGD compete with O2 to bind with HB. That increases the dissolved O2 !
13/ Bohr effect, the release of O2
Haldane effect, the opposite.