68 Questions
Which protein is responsible for iron storage and transport?
Lactoferrin
What is the coordination state of iron in the heme molecule?
+2
Which type of iron-containing enzymes are non-iron-sulfur, non-heme enzymes?
Some oxidases
What are the major classes of Iron Proteins?
Hemoproteins, iron-sulfur enzymes, and iron storage and transport proteins
Which of the following trace elements is primarily responsible for carrying oxygen as a part of hemoglobin and myoglobin?
Iron
Which of the following ultra-trace elements is considered essential for human health?
Boron
Which type of iron is affected by food components and can be free or in complexes?
Non-heme iron
What is the primary concern for trace elements in terms of their rate of bioavailability?
Bioavailability
Which type of iron is not affected by other food components?
Heme iron
What is the coordination state of iron in the heme molecule?
Fe in the +2 state
Which protein subunit contains a heme molecule in hemoglobin structure?
Each protein subunit
Which of the following trace elements is primarily responsible for carrying oxygen as a part of hemoglobin and myoglobin?
Iron
Which type of iron is not affected by other food components?
Heme iron
What is the primary concern for trace elements in terms of their rate of bioavailability?
Absorption
Which ultra-trace element is considered essential for human health?
Boron
What is the coordination state of iron in the heme molecule?
Fe(II)
Which type of iron is affected by food components like spinach?
Non-heme iron
Which protein is responsible for iron storage and transport?
Ferritin
What are the major classes of Iron Proteins?
Ferritin and Transferrin
What is the function of iron primarily as a carrier for?
Oxygen
About what percentage of the iron in the body is conserved and reused?
90%
Which amino acid can selenium replace in the body?
Cysteine
What is the 21st amino acid in the body?
Selenocysteine
Which enzyme is NOT an example of a selenoprotein?
Superoxide dismutase
What is the predominant form of thyroid hormone in the blood?
T4
Which hormone stimulates the thyroid gland to take up iodine and synthesize thyroid hormones?
Thyroid-stimulating hormone (TSH)
What is the classic sign of iodine deficiency?
Goiter
What is the most critical period for the adverse effects of iodine deficiency?
Second trimester to third year of life
What are the adverse effects of severe iodine deficiency?
All of the above
What are the adverse effects of excess iodine?
All of the above
What is the most common effect of iodine deficiency on global population?
Impaired cognitive development
Which of the following is a function of heme in the body?
Carrying oxygen
What is the primary role of hepcidin in iron regulation?
Blocking ferroportin under high iron
What is the impact of calcium intake on nonheme iron absorption?
It inhibits iron absorption
Which protein is responsible for transporting iron in the body?
Transferrin
What is the primary site for iron regulation in the body?
Intestine
What is the effect of iron deficiency on hemoglobin production?
It is affected, leading to anemia
What is the function of non-iron-sulfur, non-heme enzymes in the body?
Catalyzing various biochemical reactions
How is heme iron absorbed in the body?
It is split off from the globin in the duodenum
What can iron toxicity lead to?
Organ damage
What is the primary function of iron in the body?
Carrier for oxygen in hemoglobin and myoglobin
Which of the following is a trace element required in amounts less than 100 mg per day?
Copper
Which ultra-trace element is considered essential for human health?
Boron
What is the primary concern for trace elements in terms of their rate of bioavailability?
Low solubility
What is the primary role of ultra-trace elements without specific physiological roles, but deemed important in human health?
Antioxidant activity
What is the primary function of iodothyronine deiodinases in the body?
Producing biologically active thyroid hormone
What is the most common form of iron overload?
Hemochromatosis
What is the primary function of selenoproteins in the body?
Acting as antioxidants
What is the primary site for regulation of thyroid hormone levels?
Thyroid gland
What is the primary adverse effect of iodine deficiency on growth and development?
Neurocognitive impairment
What is the most critical period for the adverse effects of iodine deficiency?
Second trimester to third year of life
What are the adverse effects of severe iodine deficiency?
All of the above
What are the adverse effects of acute iodine poisoning?
All of the above
What is the primary effect of excess iodine on thyroid hormone production?
Increased TSH stimulation
Which protein is responsible for transporting iron in the body?
Transferrin
What is the primary role of hepcidin in iron regulation?
Inhibiting iron absorption
What can iron deficiency lead to?
Microcytic and hypochromic red blood cells
How is heme iron absorbed in the body?
Split off from the globin in the duodenum
What is the O2 carrying part of hemoglobin?
Heme
What are the major classes of iron proteins?
Hemoproteins, iron-sulfur enzymes, and iron storage and transport proteins
What is the coordination state of iron in the heme molecule?
+2 state
Which enzyme is responsible for converting iron to the 3+ state for binding to transferrin?
Ceruloplasmin
What is the most common form of iron overload, leading to organ damage?
Hemochromatosis
What is the primary role of hepcidin in iron regulation?
To block ferroportin under high iron
Which type of iron is absorbed with the aid of ascorbate (vitamin C) and low stomach pH?
Nonheme iron
What is the primary site for iron regulation in the body?
Intestine
Under high iron conditions, what does hepcidin do?
Blocks ferroportin
What is the function of hemoglobin primarily as a carrier for?
Carrying oxygen
Study Notes
Iron Absorption and Regulation in the Body
- Heme iron is absorbed into the porphyrin complex of heme and is not affected by other food components.
- Major classes of iron proteins include hemoproteins, iron-sulfur enzymes, iron storage and transport proteins, and non-iron-sulfur, non-heme enzymes.
- Hemoglobin is a 4-subunit protein with each subunit containing a heme molecule coordinated with Fe in the +2 state.
- Heme is responsible for carrying oxygen, with each heme molecule capable of carrying one O2, and the iron in the heme binding the four N of the porphyrin ring, a histidine residue, and one O2.
- Heme iron is highly bioavailable and is split off from the globin in the duodenum, with evidence of a heme-iron receptor/transporter in the enterocyte.
- Nonheme iron absorption is aided by ascorbate (vitamin C) and is influenced by stomach pH and digestive enzymes, with some evidence suggesting that calcium intake inhibits iron absorption.
- Iron in the body is stored in ferritin, transported by transferrin, and excess iron can lead to the production of hemosiderin.
- Iron regulation primarily occurs at the intestine, with iron entering cells in the 2+ state and being transported through ferroportin and transferrin.
- Regulation of iron transport involves the binding of transferrin-iron complex to transferrin receptors, which is controlled at the mRNA level depending on iron levels.
- Under high iron, hepcidin is produced by the liver to block ferroportin, whereas in iron deficiency, hemoglobin production is affected, leading to anemia.
- Iron deficiency affects an estimated 80% of the world's population, with 30% suffering from iron deficiency anemia, particularly in at-risk groups such as infants, children, adolescents, athletes, and pregnant women.
- Iron toxicity can be life-threatening, causing damage to the intestinal lining, abnormalities in body pH, and can lead to conditions such as hemochromatosis, an inherited condition that allows increased iron absorption and can result in organ damage over time.
Iron Absorption and Regulation in the Body
- Individuals living in poverty are less likely to consume adequate iron, and intestinal parasites cause blood loss, which increases iron losses.
- Iron poisoning can be life-threatening, causing damage to the intestinal lining, abnormalities in body pH, shock, and liver failure.
- Iron overload can accumulate in tissues such as the heart and the liver, with the most common form being hemochromatosis, an inherited condition leading to organ damage.
- Major classes of iron proteins include hemoproteins, iron-sulfur enzymes, and iron storage and transport proteins.
- Hemoglobin, consisting of 4 protein subunits, carries oxygen, with each heme molecule binding 4 O2.
- Heme iron is highly bioavailable and split off from the globin in the duodenum, with evidence of a heme-iron receptor/transporter in the enterocyte.
- Nonheme iron, present in the diet as FeII or FeIII, is absorbed with the aid of ascorbate (vitamin C) and low stomach pH.
- Iron in the body is stored in ferritin, transported in the blood by transferrin, and excess is stored as hemosiderin.
- Iron regulation primarily occurs in the intestine, with iron entering cells in the 2+ state through DMT1 and bound to ferritin for storage.
- Iron must be converted to the 3+ state by ceruloplasmin to bind to transferrin for transport to tissues, and its uptake by cells is regulated at the mRNA level.
- Under high iron, hepcidin is produced to block ferroportin, and when iron is deficient, hemoglobin production is affected, leading to iron deficiency anemia.
- Iron deficiency anemia results in microcytic and hypochromic red blood cells that cannot deliver sufficient oxygen to the tissues.
Test your knowledge of iron in the body with this quiz. Learn about heme and non-heme iron, the impact of food components on iron absorption, and the major classes of iron proteins. Gain insights into how the body conserves and reuses iron, and understand the role of hemoproteins like hemoglobin and myoglobin.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
