Iron absorption

Question 1

HFE

Answer 1

mutation responsible for most common absorption problems hemochromatosis

chromosome 6

protein HFE

Question 2

HJV

Answer 2

mutation responsible for jeuvanile absorption problems

protein Hemojeuvelin

chromosome 1

Question 3

TFR2

Answer 3

mutation responsible for clinically similar features to HFE but rare

chromosome 7

protein Transferrin receptor 2

Question 4

SLC40A1

Answer 4

chromosome 2

protein ferroportin

Question 5

HAMP

Answer 5

hepcidin, an iron regulation hormone critical for absorption

chromosome 19

Question 6

factors that INCREASE iron absorption

Answer 6

inadequate diet
impaired absorption 
celiac disease 
GI bleeding
hypoxia 
anemias 
decreased erythropoiesis

Question 7

factors decreasing iron absorption

Answer 7

regular blood transfusions
high iron diet
iron loading vitamins

Question 8

human hemochromatosis protein

Answer 8

HFE

functions to regulate circulating iron uptake by regulating the interaction of the TFR 1/2 with transferrin

Question 9

Hepcidin

Answer 9

key regulator of the entry of iron into circulation

Question 10

transferrin

Answer 10

iron binding blood plasma glycoprotein that controls the level of free iron in biological fluids

Question 11

TFR1

Answer 11

a protein required for iron imort from transferrin into cells by endocytosis

Question 12

TFR2

Answer 12

protein involved in uptake of transferrin bound iron into cells by endocytosis, although role is minor compared to TFR1

Question 13

Ferroportin

Answer 13

transmembrane protein that transports iron from the inside of the cell to the outside of the cell. inhabited by hepcidin, results in the retention of iron

Question 14

Low iron and Hepcidin

Answer 14

low iron decreases hepcidin, which causes ferroportin to ne expressed in order to allow iron to be absorbed by the duodenum

Question 15

High iron and hepcidin

Answer 15

high iron causes hepcidin to be high, which causes ferroportin to be prevented from bringing more iron in from the duodenum and gut

Question 16

hepcidin expression is regulated by

Answer 16

HFE, HJV, TRF2

Question 17

mutation ins HFE, HJV and TRF2 effect

Answer 17

hepcidin expression, which regulates iron absorption

Question 18

Transferrin binds two molecules

Answer 18

TRF and HFE

Transferrin and HFE compete for the TRF1 receptor, although transferrin has a higher affinity. Unbound HFE is raised to the surface of the cell which stimulates hepcidin expression

Question 19

high iron levels and TRF2

Answer 19

high iron causes TRF2 to be expressed, binding more transferrin than TRf1

TRF2 upregulates more hepcidin expression downregulates transport of Fe out of the enterocytes

Question 20

Too much iron causes more ____ to be produced than _____. Transferrins then bind more ______ than _____ because more is expressed. TRF2 binding stimulates ____ expression

Answer 20

TRF2 than TRF1

transferrins bind more TRF2 than TRF1

stimulates hepcidin production

hepcidin downregulates ferroportin which decreases Fe secretion out of enterocytes