Exam 3 - Iron

where is most iron found in the body?

hemoglobin - 65%

blood and storage - 20%

why are women more likely to be deficient in iron as compared to men

women store a lot less

which form of iron is found in animal products

heme

heme iron can be found as a part of what structures

hemoglobin

myoglobin

heme enzymes

what carrier protein does heme iron use to be absorbed

heme carrier protein 1 (hcp1)

nonheme iron is found in what sources

plant and supplementes

what form is nonheme iron found in? Where does it get reduced? what does it require to be reduced?

salt, SI, vitamin C

what transporter is used to absorb nonheme iron

divalent mineral transporter 1 (DMT1)

heme iron enters the enterocyte via the transporter ____ in the lumen of the enterocyte. This happens via ___ diffusion. Once inside the enterocyte, iron is released inside the enterocyte via ___ ____. Once it is free, the storage protein ___ binds to the iron instantly.

hcp1, facilitated, heme oxygenase, ferritin

nonheme iron (ferric 3+) is often protein bound. When it enters the stomach, digestion must occur to separate the iron from the protein. This process occurs through the use of ___ and ___. Once separated, ferric (3+) is reduced to ferrous (2+) through the use of the enzyme ____ which requires vitamin ___

pepsin and HCL (proteases)

ferrireductase

C

ferrous iron produced from nonheme digestion is absorbed via ___ diffusion using the transporter ____

facilitated, DMT

what increases iron absorption

fructose

sorbitol

acids

meat, poultry, fish

mucin

what decreases iron absorption

polyphenols in coffee and tea

phytate

oxalate

phosvitin

calcium, zinc, manganese

acid reducing meds

if the body does not need iron right away, it will bind to ___ in the enterocyte

feritin

if the body does not use iron in 2-3 days, it will be sloughed off with the lining of the ____

SI

if the body needs iron, it will be transported across the basolateral membrane by ____. During transport, it is oxidized to ___

ferroportin, Fe3+

the transport of iron by ferroportin requires what mineral

copper

what structure picks up Fe3+ after it exits the enterocyte and transports it in the plasma? where does it shuttle it to?

transferrin

liver, spleen, bone marrow

in what form is iron stored

Fe3+ bound to ferritin

what is the name of the peptide hormone produced in the liver

hepcidin

what does hepcidin bind to? why?

ferroportin

prevents transport of iron across basolateral membrane

what is the RDA of iron for

men

nonpregnant women

pregnant women

vegetarians

8mg/d

18mg/d

27mg/d

1.8X

after menopause how does the RDA of iron change for women

decreases to 8mg/day

what are some sources of iron

liver, organ meats

seafood

lean meat

poultry

what are the largest iron sources in the US

fortified cereals

bread

cakes

cookies

donuts

pasta

beef

dried beans

poultry

what are the main functions of iron

oxygen transport as part of hemoglobin and myoglobin

metabolism as cofactor for cytochromes

iron acts as a cofactor for cytochromes, what pathways are cytochromes important for?

ETC, p450 enzymes, enzymes for Vit D activation

what are symptoms of iron deficiency

pallor

fatigue

decreased cognition

short attention span

what is the most common nutritional deficiency in the US

iron

when iron deficiency is found with anemia, what kind of anemia is present

hypochromic microcytic anemia

who is at risk of iron deficiency

infants

kids 6mo-4yrs

adolescents

females of childbearing age

pregnant women

what are some causes of iron deficiency anemia

low intake

excessive blood loss

achlorhydria

consumption of mineral binders

gi lesions

iron supplements can decrease absorption of what

zinc

what are symptoms of iron toxicity

organ damage from iron deposition

GI bleeding

shock

metabolic acidosis

what is a genetic condition which can cause iron toxicity

hemochromatosis

who should not take iron supplements

postmenopausal women

older males

alcoholics