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Questions and Answers
Which trace element is essential for oxygen transport and participation in biochemical processes?
Which trace element is essential for oxygen transport and participation in biochemical processes?
What are the common oxidation states of iron?
What are the common oxidation states of iron?
What can free iron catalyze, resulting in reactive and damaging free radicals?
What can free iron catalyze, resulting in reactive and damaging free radicals?
Which proteins bind iron for storage and transport?
Which proteins bind iron for storage and transport?
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Where is the majority of total body iron found in human adults?
Where is the majority of total body iron found in human adults?
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What are the dietary sources of iron?
What are the dietary sources of iron?
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In which form does iron occur in animal sources like meat, fish, and poultry?
In which form does iron occur in animal sources like meat, fish, and poultry?
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What is the total body iron content in human adults?
What is the total body iron content in human adults?
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What percentage of total body iron is found in mobilizable 'ferritin' stores?
What percentage of total body iron is found in mobilizable 'ferritin' stores?
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What is the main function of iron binding proteins?
What is the main function of iron binding proteins?
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What is the primary function of iron in the body?
What is the primary function of iron in the body?
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Which type of iron is most easily absorbed by the body?
Which type of iron is most easily absorbed by the body?
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Where is iron stored in the body when it is not immediately needed?
Where is iron stored in the body when it is not immediately needed?
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What is the protein responsible for transporting iron throughout the body?
What is the protein responsible for transporting iron throughout the body?
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Which protein is responsible for storing oxygen in muscle cells?
Which protein is responsible for storing oxygen in muscle cells?
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What is the name of the storage protein that releases iron when the body needs it?
What is the name of the storage protein that releases iron when the body needs it?
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What is the term for a condition characterized by a lack of iron in the body?
What is the term for a condition characterized by a lack of iron in the body?
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What is the term for a condition characterized by an excess of iron in the body?
What is the term for a condition characterized by an excess of iron in the body?
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Which foods are good sources of iron?
Which foods are good sources of iron?
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What is the role of iron in energy production?
What is the role of iron in energy production?
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Which vitamin can improve the absorption of non-heme iron?
Which vitamin can improve the absorption of non-heme iron?
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What is the function of transferrin in the body?
What is the function of transferrin in the body?
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Which protein is responsible for storing iron when it is not immediately needed?
Which protein is responsible for storing iron when it is not immediately needed?
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What is the main function of hemoglobin in the body?
What is the main function of hemoglobin in the body?
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What is the main function of myoglobin in the body?
What is the main function of myoglobin in the body?
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What are the symptoms of iron deficiency anemia?
What are the symptoms of iron deficiency anemia?
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What can happen if the body has too much iron?
What can happen if the body has too much iron?
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What is the term for a condition characterized by a lack of iron in the body?
What is the term for a condition characterized by a lack of iron in the body?
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What is the role of iron in producing hemoglobin and myoglobin?
What is the role of iron in producing hemoglobin and myoglobin?
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What organs are primarily affected by iron overload?
What organs are primarily affected by iron overload?
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Which type of iron is easily absorbed by the body?
Which type of iron is easily absorbed by the body?
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What are good dietary sources of iron?
What are good dietary sources of iron?
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Which group of people is at a higher risk of iron deficiency?
Which group of people is at a higher risk of iron deficiency?
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What is the main function of iron in the body?
What is the main function of iron in the body?
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What is the term for a condition characterized by a lack of iron in the body?
What is the term for a condition characterized by a lack of iron in the body?
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What is the role of transferrin in the body?
What is the role of transferrin in the body?
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What is the function of myoglobin in the body?
What is the function of myoglobin in the body?
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Which organ is the primary physiologic source of reserve iron in the body?
Which organ is the primary physiologic source of reserve iron in the body?
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How much iron is contained in the hemoglobin needed to carry oxygen through the blood?
How much iron is contained in the hemoglobin needed to carry oxygen through the blood?
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How is iron primarily excreted from the body?
How is iron primarily excreted from the body?
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What is the term for a condition characterized by a lack of iron in the body?
What is the term for a condition characterized by a lack of iron in the body?
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What is the main cause of iron deficiency?
What is the main cause of iron deficiency?
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What is the main cause of iron overload?
What is the main cause of iron overload?
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What is the management approach for severe iron deficiency?
What is the management approach for severe iron deficiency?
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Which part of the small intestine is responsible for the largest amount of iron absorption?
Which part of the small intestine is responsible for the largest amount of iron absorption?
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What is the enzyme responsible for reducing ferric iron to ferrous iron in the small intestine?
What is the enzyme responsible for reducing ferric iron to ferrous iron in the small intestine?
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Which protein transports iron across the enterocyte's cell membrane?
Which protein transports iron across the enterocyte's cell membrane?
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Which substance enhances the absorption of non-heme iron?
Which substance enhances the absorption of non-heme iron?
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What is the main protein involved in the storage of iron?
What is the main protein involved in the storage of iron?
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What is the most convenient laboratory test to estimate iron stores in the body?
What is the most convenient laboratory test to estimate iron stores in the body?
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What is the normal transferrin saturation range in the body?
What is the normal transferrin saturation range in the body?
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Which therapy forms a complex with iron and is commonly used to eliminate iron via urine?
Which therapy forms a complex with iron and is commonly used to eliminate iron via urine?
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In individuals overloaded with iron, small amounts of free serum iron can be available due to what factor?
In individuals overloaded with iron, small amounts of free serum iron can be available due to what factor?
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Under iron overload conditions, which microorganisms can become pathogenic due to their iron dependency?
Under iron overload conditions, which microorganisms can become pathogenic due to their iron dependency?
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Which marine bacteria can cause a rapidly progressive infection in iron overloaded individuals after ingestion of contaminated food?
Which marine bacteria can cause a rapidly progressive infection in iron overloaded individuals after ingestion of contaminated food?
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What is the outcome of a rapidly progressive Vibrio vulnificus infection in iron overloaded individuals?
What is the outcome of a rapidly progressive Vibrio vulnificus infection in iron overloaded individuals?
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Which protein can be close to saturation in individuals overloaded with iron?
Which protein can be close to saturation in individuals overloaded with iron?
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Which protein is responsible for storing iron when it is not immediately needed?
Which protein is responsible for storing iron when it is not immediately needed?
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Which microorganism can become pathogenic under iron overload conditions?
Which microorganism can become pathogenic under iron overload conditions?
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What is the cause of death in iron overloaded individuals infected with Vibrio vulnificus?
What is the cause of death in iron overloaded individuals infected with Vibrio vulnificus?
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What are the two broad categories of disorders of iron metabolism?
What are the two broad categories of disorders of iron metabolism?
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What are the causes of iron deficiency?
What are the causes of iron deficiency?
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What are the symptoms of iron deficiency anemia?
What are the symptoms of iron deficiency anemia?
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What is the management approach for iron deficiency?
What is the management approach for iron deficiency?
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What are the causes of iron overload?
What are the causes of iron overload?
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What are the complications of iron overload?
What are the complications of iron overload?
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How is iron overload managed?
How is iron overload managed?
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What are the dietary sources of iron?
What are the dietary sources of iron?
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What is the main function of iron?
What is the main function of iron?
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What is the difference between heme iron and non-heme iron?
What is the difference between heme iron and non-heme iron?
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Who are at higher risk of iron deficiency?
Who are at higher risk of iron deficiency?
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What are the main functions of iron?
What are the main functions of iron?
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What is the function of heme iron?
What is the function of heme iron?
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What is the function of non-heme iron?
What is the function of non-heme iron?
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What is the purpose of iron chelating therapy?
What is the purpose of iron chelating therapy?
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Which therapy forms a complex with iron and is commonly used to eliminate iron via urine?
Which therapy forms a complex with iron and is commonly used to eliminate iron via urine?
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What role does transferrin play in iron overload and infection?
What role does transferrin play in iron overload and infection?
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Under what circumstances can usually nonpathogenic microorganisms become pathogenic?
Under what circumstances can usually nonpathogenic microorganisms become pathogenic?
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Which marine bacteria can cause a rapidly progressive infection in iron overloaded individuals after ingestion of contaminated food?
Which marine bacteria can cause a rapidly progressive infection in iron overloaded individuals after ingestion of contaminated food?
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What is the outcome of a rapidly progressive Vibrio vulnificus infection in iron overloaded individuals?
What is the outcome of a rapidly progressive Vibrio vulnificus infection in iron overloaded individuals?
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How is iron primarily excreted from the body?
How is iron primarily excreted from the body?
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What is the management approach for severe iron deficiency?
What is the management approach for severe iron deficiency?
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What are good dietary sources of iron?
What are good dietary sources of iron?
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What is the major site of iron absorption in the body?
What is the major site of iron absorption in the body?
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What are the two forms of iron that can enter the mucosal cell in the small intestine?
What are the two forms of iron that can enter the mucosal cell in the small intestine?
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What enzyme reduces ferric iron (Fe3+) to ferrous iron (Fe2+) in the small intestine?
What enzyme reduces ferric iron (Fe3+) to ferrous iron (Fe2+) in the small intestine?
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What protein transports iron across the enterocyte’s cell membrane into the cell?
What protein transports iron across the enterocyte’s cell membrane into the cell?
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What are the increasing factors that enhance iron absorption?
What are the increasing factors that enhance iron absorption?
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What are the inhibitory factors that reduce iron absorption?
What are the inhibitory factors that reduce iron absorption?
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What is the protein responsible for storing iron in intestinal lining cells?
What is the protein responsible for storing iron in intestinal lining cells?
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What is the only known iron exporter in mammals?
What is the only known iron exporter in mammals?
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True or false: Iron from animal sources is more easily absorbed than iron from plant sources.
True or false: Iron from animal sources is more easily absorbed than iron from plant sources.
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True or false: Vegetarians have a higher risk of iron deficiency.
True or false: Vegetarians have a higher risk of iron deficiency.
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True or false: Iron plays a key role in the synthesis of oxygen transporting and oxygen storage proteins.
True or false: Iron plays a key role in the synthesis of oxygen transporting and oxygen storage proteins.
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True or false: Iron is involved in DNA synthesis and repair.
True or false: Iron is involved in DNA synthesis and repair.
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True or false: Heme iron is found in plant sources like dried beans and peas.
True or false: Heme iron is found in plant sources like dried beans and peas.
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True or false: Iron deficiency can lead to anemia.
True or false: Iron deficiency can lead to anemia.
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True or false: Iron overload can lead to organ damage.
True or false: Iron overload can lead to organ damage.
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True or false: Most of the iron in the body is contained in hemoglobin?
True or false: Most of the iron in the body is contained in hemoglobin?
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True or false: Iron is lost from the body through usual excretory routes?
True or false: Iron is lost from the body through usual excretory routes?
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True or false: Iron deficiency can be caused by increased demand for iron?
True or false: Iron deficiency can be caused by increased demand for iron?
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True or false: Iron overload can be caused by genetic mutations?
True or false: Iron overload can be caused by genetic mutations?
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True or false: Hemochromatosis is more commonly seen in women than men?
True or false: Hemochromatosis is more commonly seen in women than men?
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True or false: Iron overload can lead to cirrhosis and liver tumors?
True or false: Iron overload can lead to cirrhosis and liver tumors?
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True or false: Therapeutic phlebotomy involves withdrawing small amounts of blood?
True or false: Therapeutic phlebotomy involves withdrawing small amounts of blood?
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True or false: Iron is primarily absorbed in the small intestine.
True or false: Iron is primarily absorbed in the small intestine.
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True or false: Iron can enter the mucosal cell as either the free ion or as heme iron.
True or false: Iron can enter the mucosal cell as either the free ion or as heme iron.
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True or false: Phytates and polyphenol compounds inhibit iron absorption.
True or false: Phytates and polyphenol compounds inhibit iron absorption.
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True or false: Hephaestin is a ferroxidase found mainly in the small intestine.
True or false: Hephaestin is a ferroxidase found mainly in the small intestine.
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True or false: Transferrin is the protein involved in the transport of iron in the blood.
True or false: Transferrin is the protein involved in the transport of iron in the blood.
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True or false: Serum ferritin is an indirect marker of total body iron stores.
True or false: Serum ferritin is an indirect marker of total body iron stores.
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True or false: Ferritin is the major protein involved in the storage of iron.
True or false: Ferritin is the major protein involved in the storage of iron.
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True or false: Iron chelating therapy forms a complex with iron and is commonly used to eliminate iron via urine?
True or false: Iron chelating therapy forms a complex with iron and is commonly used to eliminate iron via urine?
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True or false: Individuals overloaded with iron may have a close to saturation serum transferrin value, making small amounts of free serum iron available?
True or false: Individuals overloaded with iron may have a close to saturation serum transferrin value, making small amounts of free serum iron available?
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True or false: Microorganisms that are usually nonpathogenic can become pathogenic under iron overload conditions?
True or false: Microorganisms that are usually nonpathogenic can become pathogenic under iron overload conditions?
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True or false: Vibrio vulnificus, a marine bacteria found in oysters and commercial shellfish, can cause a rapidly progressive infection in iron overloaded individuals?
True or false: Vibrio vulnificus, a marine bacteria found in oysters and commercial shellfish, can cause a rapidly progressive infection in iron overloaded individuals?
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True or false: Normal individuals consuming the same food are entirely free of symptoms when infected with Vibrio vulnificus?
True or false: Normal individuals consuming the same food are entirely free of symptoms when infected with Vibrio vulnificus?
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True or false: Iron overload can lead to a rapidly progressive infection with death ensuing within 24 hours after ingestion of contaminated food?
True or false: Iron overload can lead to a rapidly progressive infection with death ensuing within 24 hours after ingestion of contaminated food?
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True or false: Iron overload can lead to a rapidly progressive infection with death ensuing within 24 hours after ingestion of contaminated food?
True or false: Iron overload can lead to a rapidly progressive infection with death ensuing within 24 hours after ingestion of contaminated food?
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True or false: Iron overload can lead to a rapidly progressive infection with death ensuing within 24 hours after ingestion of contaminated food?
True or false: Iron overload can lead to a rapidly progressive infection with death ensuing within 24 hours after ingestion of contaminated food?
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True or false: Iron overload can lead to a rapidly progressive infection with death ensuing within 24 hours after ingestion of contaminated food?
True or false: Iron overload can lead to a rapidly progressive infection with death ensuing within 24 hours after ingestion of contaminated food?
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Match the following types of iron with their bioavailability:
Match the following types of iron with their bioavailability:
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Match the following sources of iron with their types:
Match the following sources of iron with their types:
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Match the following functions of iron with their descriptions:
Match the following functions of iron with their descriptions:
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Match the following iron-related terms with their definitions:
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Match the following iron-related conditions with their descriptions:
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Match the following iron-related topics with their true or false statements:
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Match the following iron-related enzymes with their functions:
Match the following iron-related enzymes with their functions:
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Match the following forms of iron with their correct descriptions:
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Study Notes
Iron Metabolism and Functions
- Iron functions include:
- Synthesis of oxygen transporting and oxygen storage proteins
- Formation of heme enzymes and other iron-containing enzymes
- DNA synthesis and repair
- Dietary sources of iron:
- Animal sources (meat, fish, poultry) containing heme iron with high bioavailability
- Plant sources (dried beans, peas, fruits, and vegetables) containing non-heme iron with relatively lower bioavailability
- Vegetarians are at higher risk of iron deficiency due to lower bioavailability of non-heme iron
Iron Absorption
- Major site of absorption: small intestine (duodenum)
- Iron enters mucosal cells as free ion (ferrous form) or heme iron
- Ferric reductase enzyme (duodenal cytochrome B) reduces ferric iron (Fe3+) to ferrous iron (Fe2+)
- Divalent metal transporter 1 (DMT1) transports iron across the enterocyte's cell membrane
- Factors increasing iron absorption: ascorbic acid, HCl
- Factors inhibiting iron absorption: phytates, tannins, polyphenol compounds, achlorhydria, GI disease, antacids, iron overload, gastric bypass surgery
Iron Transport and Distribution
- Protein involved in iron transport: transferrin (glycoprotein synthesized in liver)
- Transferrin binds iron absorbed from the intestine and recycled from aging red blood cells
- Transferrin binds to specific cell surface receptors to deliver iron mainly to bone marrow and liver
- Distribution of iron:
- 0.1% in plasma
- 2.5 g in hemoglobin
- Rest in ferritin complexes (bone marrow, liver, and spleen)
Iron Storage
- Ferritin: major protein involved in iron storage
- Hemosiderin: iron storage complex composed of partially digested ferritin and iron
- Iron storage occurs in hepatocytes and reticuloendothelial cells
- Serum ferritin concentrations correlate with total body iron stores
- Serum ferritin is used as a diagnostic test for iron deficiency anemia
Iron Excretion
- Iron is conserved and not readily lost from the body
- "Excretion" occurs through the normal sloughing of tissues that are not reutilized (e.g., epidermis and gastrointestinal mucosal cells)
- Loss of about 1 mg/day occurs in a healthy adult
- Higher losses in premenopausal women (menses, parturition, etc.)
Disorders of Iron Metabolism
- Two broad categories:
- Iron Deficiency
- Iron Overload
Iron Deficiency
- Causes:
- Increased demand for iron
- Increased loss of iron (bleeding, excessive menstrual flow)
- Nutritional deficiency (lack of dietary iron or consumption of foods that inhibit iron absorption)
- Inability to absorb iron (use of acid-reducing medications)
- Damage to the intestinal lining (surgery, inflammation)
- Characteristics:
- Serum transferrin value elevated with serum iron saturation < 16%
- Liver produces more transferrin to maximize iron use
- Management:
- Careful examination for cause and source of bleeding
- Supplementation with iron (oral ferrous sulfate tablets or IV iron therapy)
- Transfusion with packed red blood cells may be indicated in severe cases
Iron Overload
- Causes:
- Genetic mutation (HFE gene) – hereditary hemochromatosis
- Secondary factors (blood transfusions, iron supplements or injections) – secondary hemochromatosis
- Characteristics:
- Iron content of the body can be elevated to values as high as 100 g
- Iron toxicity results when circulating iron exceeds transferrin availability
- Management:
- Dietary changes (avoiding iron-rich foods, alcohol, and vitamin C restriction)
- Therapeutic phlebotomy: periodic withdrawals of large amounts of blood### Iron Chelating Therapy
- Desferrioxamine is a commonly used iron chelating therapy that forms a complex with iron, called ferrioxamine, which is eliminated through urine.
- This therapy is particularly useful in cases where bleeding is not an option, such as in thalassemias.
Iron Overload and Infection
- Iron overload can lead to an increased risk of infection, as excess iron can make small amounts of free serum iron available.
- Iron-dependent microorganisms, which are usually non-pathogenic, can become pathogenic in individuals with iron overload.
- Iron overload can impair the body's ability to compete against partially saturated transferrin, allowing microorganisms to thrive.
Vibrio Vulnificus Infection
- Vibrio vulnificus is a marine bacteria found in a small percentage of oysters and commercial shellfish.
- Individuals with iron overload can develop a rapidly progressive infection with Vibrio vulnificus after consuming contaminated food.
- This infection can be fatal, with death occurring within 24 hours after ingestion of the meal.
- In contrast, normal individuals who consume the same food are typically free of symptoms.
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Test your knowledge of iron metabolism with this quiz! Learn about the role of iron in oxygen transport and its participation in biochemical processes. Explore the different oxidation states of iron and how they contribute to energy metabolism.