Erythrocyte Biochemistry

Question 1

How is iron stored in liver?

Answer 1

Ferritin

Question 2

Dcytb

Answer 2

Duodenal cyt B reduces dietary Fe3+ –> Fe2+

Question 3

DMT1

Answer 3

Transports Fe2+ into the enterocyte

Allows iron uptake into erythroblast Mito from the endosome

Question 4

Ferroportin

Answer 4

Transports Fe2+ outside the cell into blood

Question 5

Hephaestin

Answer 5

Oxidizes Fe2+ –> Fe3+ to help transport iron out of the cell into the blood

Question 6

Hepcidin

Answer 6

Peptide that regulates iron homeostasis
Binds to ferroportin and destroys it via proteolysis

Regulated by HFE
If HFE cannot bind to TfR –> no expresson of hepcidin

Question 7

Transferrin

Answer 7

Carries Fe3+ in blood to tissues (erythroblasts) that need it

Question 8

Transferrin Receptor

Answer 8

Allows binding of transferrin to erythrobloasts

Question 9

Production of RBCs are dependent on what 2 cofactors?

Answer 9

Vit B12

Flate (Folic acid)

Question 10

Megaloblastic anemia

Answer 10

Deficiency of B12 and folate

Characterized:

• Large RBCs that have normal mean cell hemoglobin content
• Blood smear shows macrocytic, normochromic cells
• Many oval macrocytes
• Red cell volume elevated

Question 11

Folate Metabolism

Answer 11

DHF –> THF (active form)
Methlyene THF is usable –> DNA synthesis

N5-methyl-THF needs to be de-methylated to enter folic acid cycle as THF

• N5-methyl-THF needs Vit B12 to become demethylated
• If B12 not available, then folate stuck as N5-Methyl-THF (folate trap)
• B12 transfers methyl group to homocysteine to create methionine using methionine synthase

Question 12

Intrinsic factor

Answer 12

Needed for B12 absorption

Question 13

Pernicious Anemia

Answer 13

Vit B12 deficiency due to lack of intrinsic factor
-A megaloblastic macrocytic anemia

Failure to absorb Vit B12 resulting from unavailability of intrinsic factor

Schilling Test