8c.7 Hemoglobin and Iron Metabolism

Question 1

What is the main molecule that transports oxygen in the body?

Answer 1

Hemoglobin.

Question 2

What is the key component inside each heme group?

Answer 2

One iron ion.

Question 3

How many heme groups does each hemoglobin molecule contain?

Answer 3

Four.

Question 4

How many oxygen molecules can each heme group bind?

Answer 4

Four oxygen molecules.

Question 5

Approximately how many hemoglobin molecules are in each red blood cell?

Answer 5

About 270 million.

Question 6

What breaks down old (senescent) red blood cells?

Answer 6

Macrophages in the spleen and liver.

Question 7

What three main components result from hemoglobin breakdown?

Answer 7

Heme, globins, and iron.

Question 8

What happens to globins when RBCs are broken down?

Answer 8

They are broken into amino acids for reuse.

Question 9

What is heme first converted into during breakdown?

Answer 9

Biliverdin.

Question 10

What color is biliverdin?

Answer 10

Green.

Question 11

What is biliverdin converted into?

Answer 11

Bilirubin.

Question 12

What color is bilirubin?

Answer 12

Yellow.

Question 13

Where does bilirubin travel after formation?

Answer 13

To the liver, then the gallbladder or directly into the intestines.

Question 14

What intestinal metabolite of bilirubin makes feces brown?

Answer 14

Stercobilin.

Question 15

What bilirubin metabolite is reabsorbed, travels to kidneys, and makes urine yellow?

Answer 15

Urobilin.

Question 16

In what form is iron released from heme during RBC breakdown?

Answer 16

Ferric iron (Fe³⁺).

Question 17

What protein transports ferric iron in the blood?

Answer 17

Transferrin.

Question 18

What is the main iron storage protein in the liver?

Answer 18

Ferritin.

Question 19

What is the less-useful backup iron storage form that can become pathologic in excess?

Answer 19

Hemosiderin.

Question 20

What form of dietary iron is easiest to absorb?

Answer 20

Ferrous iron (Fe²⁺), also known as heme iron.

Question 21

What foods primarily contain heme iron (Fe²⁺)?

Answer 21

Red meats and animal products.

Question 22

What form of iron is found in plants and cast-iron cookware?

Answer 22

Ferric iron (Fe³⁺).

Question 23

What must happen to ferric iron (Fe³⁺) before absorption?

Answer 23

It must be converted to ferrous iron (Fe²⁺).

Question 24

What intestinal cell type absorbs iron?

Answer 24

Enterocytes.

Question 25

What happens to iron after entering an enterocyte?

Answer 25

It may bind ferritin for storage, or Be exported into blood and converted back to Fe³⁺.

Question 26

What hormone regulates iron storage and release?

Answer 26

Hepcidin.

Question 27

What protein carries iron through the bloodstream?

Answer 27

Transferrin.

Question 28

Where is most transferrin-bound iron delivered for hemoglobin synthesis?

Answer 28

Bone marrow.

Question 29

What two major proteins require iron?

Answer 29

Hemoglobin and myoglobin.

Question 30

Name stages of life with high iron requirements.

Answer 30

Infancy, adolescence, pregnancy, lactation.

Question 31

Why does pregnancy increase iron demands?

Answer 31

Iron is needed for placenta and fetal development.

Question 32

What type of exercise increases iron needs and may cause iron loss?

Answer 32

Endurance exercise (due to RBC hemolysis).

Question 33

What general event always results in iron loss?

Answer 33

Blood loss.

Question 34

List causes of iron loss from blood leaving the body.

Answer 34

Trauma, surgery, cancer, ulcers, menstruation.

Question 35

What is hemolysis?

Answer 35

Breakdown of red blood cells—can occur internally (intravascular).

Question 36

Why are female endurance athletes at higher risk for iron deficiency?

Answer 36

Combination of menstrual blood loss and exercise-induced hemolysis.

Question 37

Can someone become iron deficient even with high iron intake?

Answer 37

Yes—if absorption is impaired.

Question 38

List conditions that impair iron absorption.

Answer 38

Celiac disease, Various parasitic diseases, GI bypass surgery, Chronic kidney disease, Stomach conditions, Mineral imbalances competing with iron.

Question 39

How long do new red blood cells remain in circulation?

Answer 39

~120 days.

Question 40

What nutrients and hormones are required for RBC formation?

Answer 40

Iron, globin (amino acids), vitamin B12, erythropoietin.