Iron Metabolism Flashcards
what are the functions of iron?
Transporting Oxygen: Hemoglobin, a protein in red blood cells, contains iron and is responsible for transporting oxygen from the lungs to tissues throughout the body. This is perhaps the most well-known function of iron in the body.
Myoglobin Function: Myoglobin, another iron-containing protein, is found in muscle cells. It serves as a temporary oxygen store and facilitates the diffusion of oxygen from the bloodstream to muscle mitochondria during periods of increased physical activity or when oxygen supply is limited.
DNA Synthesis: Iron is necessary for the proper function of enzymes involved in DNA synthesis. This is important for the growth, repair, and replication of cells.
Immune System: Iron plays a role in the functioning of the immune system. It is involved in the proliferation of immune cells, such as T lymphocytes, which are essential for the body’s defense against pathogens
Regulation of Body Temperature: Iron’s role in oxygen transport contributes to the regulation of body temperature because it helps deliver oxygen to cells involved in thermoregulation, such as muscle cells.
Catecholamine Metabolism: Iron is involved in the metabolism of catecholamines, which are neurotransmitters like dopamine, norepinephrine, and epinephrine. These neurotransmitters play essential roles in mood, motivation, and the stress response.
Brain Development and Function: Iron is essential for brain development, especially in infants and children. It plays a role in the formation of myelin, which insulates nerve fibers, and is involved in neurotransmitter production, influencing cognitive function and mental health.
Thyroid Function: Iron is necessary for the proper functioning of the thyroid gland, which produces hormones that regulate metabolism, energy production, and overall body function
outline the typical distribution of iron in the body
Red Blood Cells (RBCs):
Typical Amount: 2300 mg
Percent: 66%
Explanation: The majority of the body’s iron is found in haemoglobin within red blood cells. This iron is responsible for transporting oxygen throughout the body.
Macrophages:
Typical Amount: 500 mg
Percent: 14%
Explanation: Macrophages are immune cells that play a role in recycling iron from old red blood cells and other sources. They store some iron for future use.
Muscles and Other Tissues:
Typical Amount: 350 mg
Percent: 10%
Explanation: Iron is also found in myoglobin within muscle cells, where it helps with oxygen storage and utilization during muscle activity.
Liver:
Typical Amount: 200 mg
Percent: 6%
Explanation: The liver stores a significant amount of iron, primarily in the form of ferritin. This stored iron can be released into the bloodstream when needed.
Elsewhere in the Body:
Typical Amount: 150 mg
Percent: 4%
Explanation: Some iron is distributed to other tissues and organs throughout the body, including the spleen and bone marrow.
Total Iron in the body: 3500mg
Percent: 100%
outline the life cycle of RBCs
Formation of Red Blood Cells (Erythrocytes):
Red blood cells are produced in the bone marrow through a process called erythropoiesis.
Phagocytosis by Kupffer Cells:
As RBCs age or become damaged, they are removed from circulation by macrophages, particularly Kupffer cells in the liver.
Breakdown of Hemoglobin:
Hemoglobin, the protein within RBCs responsible for oxygen transport, is broken down by macrophages into its constituent parts.
Globin to Amino Acids:
The globin portion of hemoglobin is broken down into amino acids, which can be recycled for protein synthesis elsewhere in the body.
Heme to Iron:
The heme portion of hemoglobin is metabolized, and iron is released.
Iron Transported to Bone Marrow:
Iron released from heme is transported back to the bone marrow, where it can be used for the production of new RBCs during erythropoiesis.
Bilirubin Formation:
Heme is further broken down into biliverdin, which is then converted to bilirubin.
Bilirubin Transported to Bile and Gallbladder:
Bilirubin is transported to the liver, conjugated, and then excreted into bile.
Bile, including bilirubin, is stored in the gallbladder until it is released into the small intestine to aid in the digestion of fats.
explain the two sources of iron
Haem Iron:
Haem iron is iron that is bound to the heme protein found in animal tissues.
It is exclusively found in non-dairy animal sources.
Haem iron is readily absorbed by the body and is known for its high bioavailability.
Common food sources of haem iron include oysters, red meat, poultry, liver, and fish (such as sardines).
Excessive intake of foods high in haem iron can be harmful and may have health implications.
Non-Haem Iron:
Non-haem iron refers to iron that is not bound to the heme protein and is found in both animal and plant sources.
Non-haem iron can exist in various forms, including organic chelates (e.g., ferric citrate, ferrous fumarate), and it is often bound within other compounds in food.
Plant-based sources are rich in non-haem iron.
The absorption of non-haem iron from food is generally lower compared to haem iron.
Common food sources of non-haem iron include beans, nuts, lentils, green leafy vegetables, and pumpkin seeds
explain the recommended daily iron requirements for different demographic groups
Men: The recommended daily intake of iron for adult men is typically around 8 milligrams (mg) per day.
Women: Adult women, in general, have a higher daily iron requirement compared to men, with a recommended intake of approximately 18 mg of iron per day. This higher requirement is primarily due to menstrual blood loss.
Pregnant Women: Pregnant women have an even higher iron requirement, with a recommended intake of around 28 mg per day. This increased need is because the body must support the growing fetus and placenta, which require additional iron.
explain the concept of daily iron balance
Iron Intake: Adult men typically consume around 8 milligrams (mg) of iron per day. This intake can vary based on dietary choices and individual preferences.
Iron Absorption: The body absorbs approximately 1 mg of iron from the diet each day. This absorption rate can also vary depending on several factors, including the type of iron (heme or non-heme) and the presence of factors that enhance or inhibit absorption.
Unabsorbed Iron: Of the iron consumed, approximately 7 mg is not absorbed by the body and is excreted or passed through the digestive system. The unabsorbed iron can vary depending on the individual’s diet and other factors.
Iron Loss: About 1 mg of iron is lost each day, primarily through processes like skin shedding, sweat, and other minor losses. This loss is relatively consistent and cannot be significantly altered.
Total Iron Balance: To maintain a healthy iron balance, the absorbed iron (1 mg) should equal or slightly exceed the daily iron loss (1 mg). This balance ensures that the body maintains its iron stores without excess buildup or depletion.
explain iron loss in the body
Iron Loss Mechanisms:
Menstruation: For women of childbearing age, menstrual blood loss is a significant source of daily iron loss. The amount of iron lost during menstruation varies among individuals but is generally a consistent factor.
Desquamation of Epithelial Cells of the Gut: The shedding of epithelial cells from the lining of the gastrointestinal tract is another source of iron loss. This is a natural process and contributes to daily iron loss.
Minor Iron Loss Mechanisms:
While small amounts of iron are indeed lost through processes like urine, sweat, and skin cell shedding, these losses are generally minor compared to menstrual and gastrointestinal iron losses.
explain how iron is absorbed in the proximal small intestine
Iron Uptake: Dietary iron from food is initially taken up by the enterocytes (cells lining the small intestine) in the duodenum and upper jejunum. There are specific transporters on the surface of these cells that facilitate the uptake of iron from the intestinal lumen into the enterocytes.
Iron Storage: Once inside the enterocytes, iron can be stored temporarily or used for various cellular processes. Some of it is stored in the form of ferritin, an intracellular protein that helps regulate iron levels within the body.
Transport to the Bloodstream: Iron that is absorbed by enterocytes is transported across the basolateral membrane of the enterocytes into the bloodstream. This is facilitated by transport proteins such as ferroportin.
Binding to Transferrin: In the bloodstream, iron binds to a carrier protein called transferrin, which transports it to various tissues and organs in the body where it is needed.
Tissue Uptake: Iron is taken up by target cells and tissues from transferrin with the help of specific receptors on the cell membrane.
Utilization: Iron is used for various cellular processes, including the production of hemoglobin in red blood cells, the synthesis of enzymes involved in energy metabolism, and other essential functions.
