Iron in the body

In addition to its role in preventing scurvy (see Human Biochemistry box Ascorbic Acid and Scurvy and also Chapter 6), ascorbic acid also plays important roles in the brain and nervous system. It also mobilizes iron in the body, prevents anemia, ameliorates allergic responses, and stimulates the immune system. 

Iron deficiency Anemia characterized by an inadequate amount of iron in the body to produce hemoglobin... 

The protein that stores iron in the body is called ferritin. A ferritin molecule consists of a protein coat and an iron-containing core. The outer coat is made up of 24 pol3q5eptide chains, each with about 175 amino acids. As Figure 20-27 shows, the pol q5eptides pack together to form a sphere. The sphere is hollow, and channels through the protein coat allow movement of iron in and out of the molecule. The core of the protein contains hydrated iron(HI) oxide, FC2 O3 H2 O. The protein retains its shape whether or not iron is stored on the inside. When filled to capacity, one ferritin molecule holds as many as 4500 iron atoms, but the core is only partially filled under normal conditions. In this way, the protein has the capacity to provide iron as needed for hemoglobin s mthesis or to store iron if an excess is absorbed by the body. 

Iron is an essential element, for humans and for many forms of life, but even a modest excess can be toxic as the human body does not have an effective iron excretion mechanism. It is therefore necessary to maintain an appropriate level of iron in the body, to supply iron in absorbable form if it is deficient (anemia) and to remove iron if present in excess. Inorganic coordination chemistry plays an important role in dealing with these complementary conditions of deficiency and of excess. The latter condition is much more common than often supposed, for there are a number of conditions, such as hemochromatosis and thallasemia, where the build-up of iron in essential organs is eventually lethal. Mild iron poisoning is not infrequent in children, while even iron fortification of foodstuffs can have adverse effects. Mild iron poisoning can be treated with bicarbonate or phosphate, which presumably complex and precipitate the iron. ... 

The standard patient has a mass of 70 kg, and the density of the human body is very close to 1 g/mL. What is the body volume of the standard patient in liters Based on this volume and using the data in Table 3.1, determine the molar concentration of iron in the body. Assume all the iron in the body is evenly distributed throughout all tissues. Repeat the calculation on selenium, an element involved in certain oxidation-reduction processes in the body. The lesson of this question is that trace elements can be very trace indeed. 

Most of the iron in the body is in the form of haemoglobin in red blood cells and myoglobin in muscle. The remainder is in the liver, spleen and other tissues. Haemoglobin is essential for the proper functioning of every organ and tissue of the body. Iron has a rapid turnover rate in the chicken therefore, it must be provided in a highly available form in the diet on a daily basis. Iron deficiency can result in microcytic, hypochromic anaemia in poultry. Any internal infection such as coccidiosis can also interfere with iron absorption and lead to a deficiency. 

The efficiency with which virulent bacteria invade and grow in fluids and tissues of animals suggests that they may differ from avirulent bacteria by the prolific production of siderophores. Recent experimental results showed that bacteria differ in the ability to acquire iron in the body of the host. The virulence and the ability of Pseudomonas aeruginosa to use iron in mice was significantly increased after 16 serial passages of the bacteria in these animals (31). Rogers experiments suggested that there is a direct relationship between the ability to synthesize entero-chelin and the virulence of different strains of E. coli for mice (8) since virulent bacteria exposed to iron limitation produced much more entero-chelin than avirulent bacteria. 

The adult human has a total of 4-5 g of body iron, mostly in the form of haemoglobin within red cells (Fig. 1). As each unit of blood (about one pint) contains approximately 250 mg of iron, repeated blood transfusion will lead inevitably to an excess accumulation of iron in the body. Unlike other mammals, human iron metabolism is highly conservative and there is no effective mechanism for removal of excess iron other than by blood loss [17]. 

Q3 Both the low haemoglobin content of the blood and the reduced haematocrit are consistent with anaemia. The low mean corpuscular volume shows the red cells are small, a characteristic feature of iron-deficiency anaemia. The low concentration of ferritin, which reflects the amount of iron stored in the body, is also consistent with a deficiency of iron in the body. 

Q5 Chloe appears to be suffering from iron-deficiency anaemia as her red blood cells are small (microcytic). In addition her ferritin level is low. Iron is stored as ferritin, so a reduction in ferritin concentration reflects a decreased store of iron in the body, a state which is characteristic of iron-deficiency anaemia. In... 

Q4 Excessive bleeding during the menstrual period is called menorrhagia. The blood loss reduces levels of iron in the body and may result in iron-deficiency anaemia. The causes of excessive bleeding could be inflammation, fibroids, endometriosis, cervical polyps, adenomyosis, ovarian tumours, intrauterine devices (IUDs), inherited clotting disorders, endocrine dysfunction, such as thyroid dysfunction, or mental stress. In terms of drug therapy, oral ferrous... 

Serum transferrin has a more specialized fimction than simply iron sequestration, transporting iron from sonrces of iron in the body (e g. after absorption throngh the... 

Iron is potentially toxic in all forms and by all routes of exposure. The inhalation of large amounts of iron dust results in iron pneumoconiosis (arc welder s lung). Chronic exposure to excess levels of iron (>50-100 mg Fe/day) can result in pathological deposition of iron in the body tissues, the symptoms of which are fibrosis of the pancreas, diabetes mellitus, and liver cirrhosis. 

Ferritin neutralizes the intracellular toxicity of iron and effects its water-solubility. It is formed in the RES (as well as at the polysomes of the liver cells) and degraded in the lysosomes. The serum ferritin value corresponds to the total amount of mobilizable depot iron in the body. (31, 66, 67)... 

Haemochromatosis (HC) is a hereditary disease (autosomal recessive) affecting the iron metabolism. It refers to pronounced iron deposition, predominantly in the liver (>50% of the total iron in the body), but also in other organs, such as pancreas, spleen, heart, endocrinium, bone marrow, lymph nodes, salivary glands, basal skin layers and gastrointestinal epithelia. In addition to these hereditary (HFE-related) or idiopathic (non-HFE-related) primary forms, there are numerous acquired secondary forms of HC. At first, the cells of the RES become laden with iron. Only when the capacity of the RES is exceeded is there iron deposition in the parenchymal cells this leads to damage of the respective organs, (s. tab 31.17)... 

Ascorbic acid promotes the absorption of iron, a reason for caution in giving high doses to patients with iron overload (SEDA-9, 324). In particular, patients with hemochromatosis, polycythemia, and leukemia who present with marked iron overload should keep their intake of ascorbic acid to a minimum (42). However, ascorbic acid can also interfere with the distribution of iron in the body in these patients. One consequence is that in patients with iron overload who also have scurvy, iron tends to be deposited in the reticuloendothelial system rather than the parenchymal cells, which may reduce the risks of damage to the liver, heart, or endocrine glands. It has conversely been noted that in beta-thalassemia major... 

Since circulating deferiprone-iron complexes can easily dissociate, deferiprone can redistribute iron in the body (14). Although this might theoretically lead to the precipitation or aggravation of heart failure (14), no such cases have as yet been reported. 

This argument is logical and scientifically accurate with respect to the transfer of iron in the body. However, it does not address the potential importance of the thermodynamic stability constants of the two common valence forms of iron (II and III) with ligands in food. 

Iron—Metabolism—Congresses. 2. Iron in the body—Congresses. 

There is 3.5 to 4.5 grams of iron in the body, with 70 percent of it in the hemoglobin (blood) and 10 percent in the myoglobin (muscles). Iron is absorbed by the duodenum and small intestines and carried by the blood into the bone marrow. 

The toxicity of acute iron poisoning includes local effects on the gastrointestinal mucosa and systemic effects induced by excessive iron in the body. Iron is irritating to the gastric and duodenal mucosa, which may result in hemorrhage and occasional perforations. Once... 

Similarly, the lower accessibility of tyrosyl residues to base titration in ferric lactoferrin compared to ferric transferrin has been suggested to be linked to their relative stabilities as metallocomplexes 67, 163). Ferric conalbumin also appears to be more stable than ferric transferrin 157). These stability differences may be of biological significance given that a role of the serum protein is to distribute iron in the body rather than to sequester the metal. 

The presence of too much iron in the body can also cause problems. People who suffer from hemochromatosis retain too much iron, causing it to accumulate in various organs, including the spleen, heart, and liver. Hemochromatosis can cause joint pain, heart failure, liver failure, or diabetes. 

There are 50-70 mmol (3-4 g) of iron in the body. Three-quarters are present as the molecular complex with haem. Most of the remainder is in tissue stores bound to the iron storage proteins, ferritin and haemosiderin. Less than one per cent of total body iron is in the plasma, where it is associated with the iron-binding protein, transferrin. Body iron is efficiently reutilized. Dietary intake is about 0.35 mmol (20 mg) per day. The factors which regulate intestinal absorption of iron are poorly understood (Fig. 2). 

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