rbc recycling

step 1

Macrophages in the spleen and liver or rbm phagocytize ruptured of worn out rbcs

step 2

globin and heme split apart

step 3

globin is broken down into aa, for syn of other proteins

step 4

iron is removed from heme as Fe3+ , asso with plasma protein transferrin

step 5

in muscle fibers, liver cells, macrophages of the spleen and liver, Fe3+ detaches from transferrin, attaches to iron storage protein ferritin

step 6

once releases from storage site or absorption from the GI tract, Fe3+ reattaches to transferrin

7

Fe3+ transferrin complex is carried to rbm, where RBC precursor cells move it through receptor mediated endocytosis for use in hemoglobin synthesis

8

erythropoiesis in RBM = production of RBCs, they enter circulation

9

when iron is removed from heme, non iron portion of heme is converted into biliverdin (green) then bilirubin (yellow)

10

bilirubin (y) enters the blood and is transported to the liver

11

in the liber bilirubin (y) is released by the liver cells into bile, through small then large intestine

12

in the large intestine bacteria converts bilirubin into urobilinogen

13

some urobilinogen is reabsorbed into blood, coverted into yellow - urobilin of urine

14

most urobilinogen is shat out in stercobilin