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Trace metals are the metals subset of trace elements; that is, metals normally present in small but measurable amounts in animal and plant cells and tissues and that are a necessary part of nutrition and physiology. Some biometals are trace metals. Ingestion of, or exposure to, excessive quantities can be toxic. However, insufficient plasma or tissue levels of certain trace metals can cause pathology, as is the case with iron.
Trace metals within the human body include iron, lithium, zinc, copper, chromium, nickel, cobalt, vanadium, molybdenum, manganese and others. [1] [2] [3]
Trace metals are metals needed by living organisms to function properly and are depleted through the expenditure of energy by various metabolic processes of living organisms. They are replenished in animals through diet as well as environmental exposure, and in plants through the uptake of nutrients from the soil in which the plant grows. Human vitamin pills and plant fertilizers can be a source of trace metals.
Trace metals are sometimes referred to as trace elements, although the latter includes minerals and is a broader category. See also Dietary mineral. Trace elements are required by the body for specific functions. Things such as vitamins, sports drinks, fresh fruits and vegetables are sources. Taken in excessive amounts, trace elements can cause problems. For example, fluorine is required for the formation of bones and enamel on teeth. However, when taken in an excessive amount can cause a disease called "Fluorosis', in which bone deformations and yellowing of teeth are seen. Fluorine can occur naturally in some areas in ground water.
Roughly 5 grams of iron are present in the human body and is the most abundant trace metal. [1] It is absorbed in the intestine as heme or non-heme iron depending on the food source. Heme iron is derived from the digestion of hemoproteins in meat. [4] Non-heme iron is mainly derived from plants and exist as iron(II) or iron(III) ions. [4]
Iron is essential for more than 500 hemeproteins, the likes of which include hemoglobin and myoglobin, and account for 80% of iron usage. [1] The other 20% is present in ferritin, hemosiderin, [1] iron-sulfur (Fe/S) proteins, such as ferrochelatase, and more.
A relatively non-toxic metal to humans and the second most abundant, the body has 2-3 grams of zinc. [1] It can enter the body through inhalation, skin absorption, and ingestion, [5] with the latter of the bunch being the most common. The mucosal cells of the digestive tract contain metallothionein proteins that store the zinc ions. [1]
Nearly 90% of zinc is found in the bones, muscles, [5] and vesicles in the brain. [1] Zinc is a cofactor in hundreds of enzyme reactions and a major component of zinc finger proteins.
The third most abundant trace metal in the human body. [1]
It is found in cytochrome c oxidase, a protein necessary for the electron transport chain in mitochondria. [1]
Zinc is a chemical element with the symbol Zn and atomic number 30. Zinc is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic table. In some respects, zinc is chemically similar to magnesium: both elements exhibit only one normal oxidation state (+2), and the Zn2+ and Mg2+ ions are of similar size. Zinc is the 24th most abundant element in Earth's crust and has five stable isotopes. The most common zinc ore is sphalerite (zinc blende), a zinc sulfide mineral. The largest workable lodes are in Australia, Asia, and the United States. Zinc is refined by froth flotation of the ore, roasting, and final extraction using electricity (electrowinning).
A nutrient is a substance used by an organism to survive, grow, and reproduce. The requirement for dietary nutrient intake applies to animals, plants, fungi, and protists. Nutrients can be incorporated into cells for metabolic purposes or excreted by cells to create non-cellular structures, such as hair, scales, feathers, or exoskeletons. Some nutrients can be metabolically converted to smaller molecules in the process of releasing energy, such as for carbohydrates, lipids, proteins, and fermentation products, leading to end-products of water and carbon dioxide. All organisms require water. Essential nutrients for animals are the energy sources, some of the amino acids that are combined to create proteins, a subset of fatty acids, vitamins and certain minerals. Plants require more diverse minerals absorbed through roots, plus carbon dioxide and oxygen absorbed through leaves. Fungi live on dead or living organic matter and meet nutrient needs from their host.
A period 4 element is one of the chemical elements in the fourth row of the periodic table of the chemical elements. The periodic table is laid out in rows to illustrate recurring (periodic) trends in the chemical behaviour of the elements as their atomic number increases: a new row is begun when chemical behaviour begins to repeat, meaning that elements with similar behaviour fall into the same vertical columns. The fourth period contains 18 elements beginning with potassium and ending with krypton – one element for each of the eighteen groups. It sees the first appearance of d-block in the table.
Metalloprotein is a generic term for a protein that contains a metal ion cofactor. A large proportion of all proteins are part of this category. For instance, at least 1000 human proteins contain zinc-binding protein domains although there may be up to 3000 human zinc metalloproteins.
A trace element, also called minor element, is a chemical element whose concentration is very low. They are classified into two groups: essential and non-essential. Essential trace elements are needed for many physiological and biochemical processes in both plants and animals. Not only do trace elements play a role in biological processes but they also serve as catalysts to engage in oxidation and reduction mechanisms.
In the context of nutrition, a mineral is a chemical element required as an essential nutrient by organisms to perform functions necessary for life. However, the four major structural elements in the human body by weight, are usually not included in lists of major nutrient minerals. These four elements compose about 96% of the weight of the human body, and major minerals (macrominerals) and minor minerals compose the remainder.
Calcium ions (Ca2+) contribute to the physiology and biochemistry of organisms' cells. They play an important role in signal transduction pathways, where they act as a second messenger, in neurotransmitter release from neurons, in contraction of all muscle cell types, and in fertilization. Many enzymes require calcium ions as a cofactor, including several of the coagulation factors. Extracellular calcium is also important for maintaining the potential difference across excitable cell membranes, as well as proper bone formation.
Bioinorganic chemistry is a field that examines the role of metals in biology. Bioinorganic chemistry includes the study of both natural phenomena such as the behavior of metalloproteins as well as artificially introduced metals, including those that are non-essential, in medicine and toxicology. Many biological processes such as respiration depend upon molecules that fall within the realm of inorganic chemistry. The discipline also includes the study of inorganic models or mimics that imitate the behaviour of metalloproteins.
Biometals are metals normally present, in small but important and measurable amounts, in biology, biochemistry, and medicine. The metals copper, zinc, iron, and manganese are examples of metals that are essential for the normal functioning of most plants and the bodies of most animals, such as the human body. A few are present in relatively larger amounts, whereas most others are trace metals, present in smaller but important amounts. Approximately 2/3 of the existing periodic table is composed of metals with varying properties, accounting for the diverse ways in which metals have been utilized in nature and medicine.
In biochemistry, an ultratrace element is a chemical element that normally comprises less than one microgram per gram of a given organism, but which plays a significant role in its metabolism.
Iron is an important biological element. It is used in both the ubiquitous Iron-sulfur proteins and in Vertebrates it is used in Hemoglobin which is essential for Blood and oxygen transport.
Copper deficiency, or hypocupremia, is defined either as insufficient copper to meet the needs of the body, or as a serum copper level below the normal range. Symptoms may include fatigue, decreased red blood cells, early greying of the hair, and neurological problems presenting as numbness, tingling, muscle weakness, and ataxia. The neurodegenerative syndrome of copper deficiency has been recognized for some time in ruminant animals, in which it is commonly known as "swayback". Copper deficiency can manifest in parallel with vitamin B12 and other nutritional deficiencies.
Body composition may be analyzed in various ways. This can be done in terms of the chemical elements present, or by molecular type e.g., water, protein, fats, hydroxylapatite, carbohydrates and DNA. In terms of tissue type, the body may be analyzed into water, fat, connective tissue, muscle, bone, etc. In terms of cell type, the body contains hundreds of different types of cells, but notably, the largest number of cells contained in a human body are not human cells, but bacteria residing in the normal human gastrointestinal tract.
Animal nutrition focuses on the dietary nutrients needs of animals, primarily those in agriculture and food production, but also in zoos, aquariums, and wildlife management.
Manganese is an essential biological element in all organisms. It is used in many enzymes and proteins It is essential in plants.
Copper is an essential trace element that is vital to the health of all living things. In humans, copper is essential to the proper functioning of organs and metabolic processes. The human body has complex homeostatic mechanisms which attempt to ensure a constant supply of available copper, while eliminating excess copper whenever this occurs. However, like all essential elements and nutrients, too much or too little nutritional ingestion of copper can result in a corresponding condition of copper excess or deficiency in the body, each of which has its own unique set of adverse health effects.
Metals in medicine are used in organic systems for diagnostic and treatment purposes. Inorganic elements are also essential for organic life as cofactors in enzymes called metalloproteins. When metals are scarce or high quantities, equilibrium is set out of balance and must be returned to its natural state via interventional and natural methods.
Evolution of metal ions in biological systems refers to the incorporation of metallic ions into living organisms and how it has changed over time. Metal ions have been associated with biological systems for billions of years, but only in the last century have scientists began to truly appreciate the scale of their influence. Major and minor metal ions have become aligned with living organisms through the interplay of biogeochemical weathering and metabolic pathways involving the products of that weathering. The associated complexes have evolved over time.
Zinc is an essential trace element for humans and other animals, for plants and for microorganisms. Zinc is required for the function of over 300 enzymes and 1000 transcription factors, and is stored and transferred in metallothioneins. It is the second most abundant trace metal in humans after iron and it is the only metal which appears in all enzyme classes.
Cobalt is essential to the metabolism of all animals. It is a key constituent of cobalamin, also known as vitamin B12, the primary biological reservoir of cobalt as an ultratrace element. Bacteria in the stomachs of ruminant animals convert cobalt salts into vitamin B12, a compound which can only be produced by bacteria or archaea. A minimal presence of cobalt in soils therefore markedly improves the health of grazing animals, and an uptake of 0.20 mg/kg a day is recommended because they have no other source of vitamin B12.
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