Iron metabolism

Question 1

for iron (micromineral) we require

Answer 1

8-18 mg/day
3-4g in our bodies
can be toxic (reactive oxygen species)
found in heme-bound form and non-heme

Question 2

iron functions

Answer 2

oxygen transport
respiration (ETC)
detoxification (SOD, P450s)
nitrogen fixation (bacteria)

Question 3

sources of iron

Answer 3

red meant, poultry, fish, beans, lentils, fortified foods

Question 4

Iron regulation

Answer 4

tightly regulated absorption
there is no regulation of iron excretion
iron can be toxic
requirements vary with sex and age

Question 5

Iron distribution

Answer 5

muscle -> myoglobin
bone marrow -> RBC production
circulating erythrocytes -> hemoglobin
liver -> main storage organ
intestine -> main iron absorption organ
reticuloendothelial macrophages -> destruction of RBC

Question 6

Iron absorption

Answer 6

heme iron from meat
non-heme iron from plants
takes place in intestine

Question 7

iron utilization

Answer 7

bone marrow for RBC production
RBC for oxygen transport

Question 8

iron storage

Answer 8

liver

Question 9

Iron absorption
non-heme

Answer 9

duodenal cytochrome b
divalent metal transporter
ferritin
less efficient

Question 10

iron absorption
heme

Answer 10

heme carrier protein
heme oxygenase
ferritin
more efficient

Question 11

iron intracellular storage: ferritin

Answer 11

24 monomers arranged in sphere
can be measured
ferroxidase activity
positive acute phase reactant

Question 12

Iron export

Answer 12

Ferroportin -> only iron exporter
Hephaestin -> oxidizes iron
Tranferrin -> binds and transports iron

Question 13

Iron export takes place from

Answer 13

enterocytes
hepatocytes
RE macrophages

Question 14

Iron import

Answer 14

tranferrin -> binds and transports iron
tranferrin receptor -> binds Tf-Fe and internalizes it
divalet metal transporter -> export iron out of endosome

Question 15

iron import takes place from

Answer 15

erythroid cells
hepatocytes

Question 16

how control iron transport?

Answer 16

hepcidin
erythroferrone

Question 17

nutritional immunity

Answer 17

negative acute phase reactant
hepcidin
iron withholding

Question 18

Nutritional immunity

Answer 18

iron required for bacterial growth
reducing iron availability can slow down an infection
infections induce inflammatory response
nutritional immunity:
increase hepcidin
decrease serum iron
decrease bacterial growth

Question 19

Iron homeostasis and translational regulation

Answer 19

low iron: IRP binds IRE and that allows for more translation for more iron in bodies
high iron: IRP does not bind and mRNA is degraded so no TtR made

Question 20

iron deficiency

Answer 20

anemia: low hemoglobin
extreme fatigue
dizziness
usually not fatal
multiple causes

Question 21

iron deficiency
RBCs

Answer 21

carry hemoglobin
iron def. affects RBC size/color
microcytic hypochromic anemia

Question 22

how to assess iron status

Answer 22

look at:
ferritin
transferrin
transferrin receptor

Question 23

anemia

Answer 23

pregnant women
poor absorption
dietary restrictions
blood loss

Question 24

prevent anemia

Answer 24

iron
vitamin C
folate
vitamin B12

Question 25

anemia of chronic disease

Answer 25

untreated chronic infection
increased hepcidin expression
nutritional immunity
iron withholding
ex. microcytic or macrocytic

Question 26

hereditary hemochromatosis

Answer 26

mutations in hepcidin, ferroportin, and regulators of hepcidin
excess amonts of iron are absorbed
liver, heart, and pancreas are affected
phlebotomies are recommended

Question 27

Iron overlaod

Answer 27

difficult to get dietary iron overload
possible to get iron poisoning with supplements
if GI track damaged, poisoning is more likely
chelating agents can be used