Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
37 Cards in this Set
- Front
- Back
|
Functions:
1. Enzyme cofactors 2. Structural functions (Calcium, Phosphorus, Magnesium in bone) 3. Electrolyte balance (Chloride, Sodium, Potassium) 4. Nerve and muscle function 5. Unique functions: heme, hormonal responses, muscle contractility.. |
Minerals
Inorganic elemental atoms that are essential nutrients. Not changed by digestion or metabolism |
|
|
Name the classification of mineral:
- Sodium - Potassium - Magnesium - Calcium - Phosphorus - Sulfur - Chloride Present in body tissues at concentration >50 mg/kg |
Macrominerals
Humans need >100mg/day |
|
|
Name the classification of mineral:
- Chromium - Manganese - Iron - Molybdenum - Copper - Cobalt - Zinc - Fluoride - Iodine - Selenium - Tin - Nickel Present in body tissues at a concentration <50mg/kg |
Trace or Microminerals
Humans need <100mg/day |
|
|
Name the mineral:
Functions: Bone structure Nerve function Blood clotting Muscle contraction Cellular metabolism (enzymes) Recommendations: 1000-1500 mg/day (AI) |
Calcium
Most abundant mineral in animal tissues 99% in bone, also in blood and other tissues |
|
|
Three “hormones” involved
in regulation of this mineral 1. Vitamin D (increase plasma Ca++) 2. Parathyroid hormone (increase plasma Ca) 3. Calcitonin (decrease plasma Ca) |
Calcium
|
|
|
Name the mineral
Functions: Found in bones and teeth Found in all cells as part of a major buffer system (acid-base balance) Forms part of DNA , RNA and ATP (necessary for all growth) Energy metabolism (enzyme activation/inhibition) second messenger (cAMP, IP3) Structural component (phospholipids in membranes ) |
Phosphorus
Second most abundant mineral in the body (phosphate form). 85% is found combined with calcium in the hydroxyapatite crystals of bones and teeth |
|
|
Name the mineral:
Functions: Formation of bones and teeth Aids in absorption of calcium and potassium Enzyme function. Also as a part of the utilizable form of ATP Involved in muscle contraction and blood clotting (inhibition) Support the functioning of the immune system |
Magnesium
Barely a major mineral (1 ounce in a 130-pound person) 50% in bones (reservoir) and the rest is in muscle, soft tissues (only 1% extracellular) |
|
|
PTH controls ________ of phosphate.
|
secretion
|
|
|
Minerals that comprise < 0.01% of the body weight
Needed in concentrations of < 100 mg needed per day RDAs have been established for: Iron, zinc, copper, iodine, selenium, and molybdenum Adequate intakes estimated for Manganese, fluoride, chromium Many are involved as cofactors in enzymes |
Microminerals
|
|
|
Minerals that comprise < 0.01% of the body weight
Needed in concentrations of < 100 mg needed per day |
Microminerals
|
|
|
Recommended _______ allowances have been established for:
- Iron - zinc - copper - iodine - selenium - molybdenum |
Recommended daily allowances
|
|
|
Needed in concentrations of < 100 mg needed per day
|
Microminerals
|
|
|
Adequate ________ have been estimated for:
- Manganese - Fluoride - Chromium |
Adequate intakes
|
|
|
_____ is important in a multitude of chemical reactions in the body
Part of the catalytic center of over 300 metalloenzymes (Carbonic anhydrase, Alkaline phosphatase, Alcohol dehydrogenase, Superoxide dismutase..) Gene expression (zinc fingers in transcription factors and nuclear hormone receptors) - Important in protein-protein interactions and signal transduction |
Zinc
Found in all organs and tissues; highest in bone, liver, kidney, muscle and skin Can exist in different valence states but in the body is always found in its divalent form (Zn2+) |
|
|
Shown to improve the immune status in the elderly
Used therapeutically to promote wound healing and to treat gastric ulcers |
Zinc Supplementation
|
|
|
One of the most abundant elements in nature and essential for human health
Potentially toxic: major generator of free radicals There are disease states associated with having either too little (iron deficiency) or too much iron (iron overload) and are among the most common human diseases |
Iron
Human iron metabolism is tightly regulated to maintain iron homeostasis |
|
|
Cofactor to enzymes involved in oxidation-reduction reactions (due to its capacity to accept
and donate electrons readily, interconverting between ferrous (Fe2+) and ferric (Fe3+) forms. |
Roles of Iron
|
|
|
Present only in animal foods derived from flesh (good absorption)
|
Heme iron
|
|
|
Present in plant and animal derived food (poor absorption)
|
Non-heme iron
|
|
|
At physiological pH ferrous iron (Fe2+) is oxidized to the insoluble ferric iron (Fe3+)
The acidic gastric compartment lowers the pH in the proximal duodenum helping to solubilize the ferric iron (=> pH is important) This facilitates the activity of the brush border ferrireductases (reduce Fe3+ to Fe2+) and subsequent transport into the enterocyte by the DMT1* transporter |
Nonheme iron:
Absorption occurs mainly in the duodenum |
|
|
- Absorption is independent of pH.
Mechanism of absorption not well characterized(endocytosis?) Once absorbed, the porphryin ring is hydrolyzed by heme oxygenase into inorganic ferrous iron and protoporphyrin |
Heme iron:
Absorption occurs mainly in the duodenum |
|
|
The average adult stores about 3-5 grams of iron
About 1-2 mg of iron is lost each day through sloughing of cells from skin and mucosal surfaces, including the lining of the gastrointestinal tract |
Iron distribution
|
|
|
Iron distribution:
60-70% Hemoglobin 10-15% Myoglobin 2% Heme enzymes 2% Non Heme enzymes |
Functional iron:
|
|
|
Iron distribution:
Circulates in plasma bound to transferrin (0.1%) |
Transported Iron:
|
|
|
Iron distribution:
Ferritin & hemosiderin (3-10%) |
Stored Iron*:
|
|
|
Inhibitors of heme absorption
Prevent conversion of Heme -> Fe2+ -> Fe3+ |
- Phytates
- Tannins, - Antiacids Strong chelators, ↑ pH |
|
|
Facilitators of heme absorption
Promote conversion of Heme -> Fe2+ -> Fe3+ |
- Ascorbate,
- Citrate - Amino acids Weak chelators |
|
|
Competitors of iron absorption
|
- Lead
- Cobalt - Manganese - Zinc Compete for the divalent metal transporter (DMT) |
|
|
The average adult stores about ____ milligrams of iron
|
3-5 milligrams
|
|
|
About ___ mg of iron is lost each day through:
Sloughing of cells from skin and mucosal surfaces. - Including the lining of the gastrointestinal tract |
1-2 milligrams
|
|
|
This type of heme is stored in parenchymal cells of the:
1. Liver, 2. Spleen, 3. Bone marrow 4. Reticuloendothelial macrophages |
Stored Iron
Ferritin & hemosiderin (3-10%) These macrophages provide most of the usable iron by degrading hemoglobin in senescent erythrocytes and reloading ferric iron onto transferrin for delivery to cells. |
|
|
Normally, iron binds to _______.
|
Ferrin (instead of plasma bound transferrin)
|
|
|
1. The average red cell life span is 120 days (0.8–1.0% of red cells turn over each day)
2. The senescent red cell is recognized by the cells of the RE* system and undergoes phagocytosis 3. The hemoglobin from the ingested red cell is broken down and the iron is shuttled back to the surface of the RE cell, where it is presented to circulating transferrin 4. This highly conserved recycling of iron from senescent red cells can support steady state erythropoiesis 5. Any additional iron required for daily red cell production comes from the diet |
Recycling of heme.
Approximately 70% of total body iron is incorporated into red cell hemoglobin An average adult produces 2 x 10^11 red cells daily Each red cell contains more than a billion atoms of iron |
|
|
- Iron is a critical element in the function of all cells
- The amount of iron required by individual tissues varies during development and under some circumstances (increased erythropoiesis). RBC require very high levels of iron daily. - The body must protect itself from free iron (participates in chemical reactions that generate free radicals => toxic) - Consequently, elaborate mechanisms have evolved that allow iron to be made available for physiologic functions while at the same time conserving this element and handling it in such a way that toxicity is avoided |
Reasons why iron is important in homeostasis
|
|
|
1. Absorption:
- Dietary regulator - Storage regulator - Erythropoietic regulator - Hormonal: hepcidin (inhibit absorption) 2) Transport and storage: regulated by iron at the protein synthesis and mRNA stability level (ferritin and transferrin receptor) 3) Recycling 4) Losses: blood loss (via gastrointestinal bleeding, menses, or other forms of bleeding) and the loss of epithelial cells from the skin, gut, and genitourinary tract |
Regulation of heme homeostasis
|
|
|
What is the purpose of the hormone hepcidin?
|
Inhibit iron absorption
Binds to ferrocortin |
|
|
Transport and storage of iron is regulated by which two receptors?
|
ferritin and transferrin receptor
|
