Albumins Health Dictionary

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Albumins: From 1 Different Sources

Albumins are water-soluble proteins which enter into the composition of all the tissues of the body. Albumins are generally divided according to their source of origin, as muscle-albumin, milk-albumin, blood- or serum-albumin, egg-albumin, vegetable-albumin, etc. These di?er both in chemical reactions and also physiologically. Serum-albumin occurs in blood PLASMA where it is important in maintaining plasma volume.

When taken into the stomach, all albumins are converted into a soluble form by the process of DIGESTION and then absorbed into the blood, whence they go to build up the tissues. Albumin is synthesised in the liver, and in chronic liver disease this process is seriously affected. (See PROTEINURIA; KIDNEYS, DISEASES OF – Glomerulonephritis.)

Health Source: Medical Dictionary
Author: Health Dictionary

Colostrum

The ?rst ?uid secreted by the mammary glands for two or three days after childbirth. It contains less CASEIN and more albumin (see ALBUMINS) than ordinary milk.... colostrum

Enteral Feeding

In severely ill patients, the metabolic responses to tissue damage may be su?cient to cause a reduction of muscle mass and of plasma proteins. This state of CATABOLISM may also impair the immune response to infection and delay the healing of wounds. It is probable that as many as one-half of patients who have had a major operation a week previously show evidence of protein malnutrition. This can be detected clinically by a loss of weight and a reduction in the skinfold thickness and arm circumference. Biochemically the serum-albumin (see ALBUMINS) concentration falls, as does the LYMPHOCYTE count. The protein reserves of the body fall even more dramatically when there are SEPSIS, burns, acute pancreatitis or renal failure.

The purpose of enteral feeding is to give a liquid, low-residue food through a naso-gastric feeding tube. It has the advantage over parenteral nutrition that the septic complications of insertion of CATHETERS into veins are avoided. Enteral feeding may either take the form of intermittent feeding through a large-bore naso-gastric tube, or of continuous gravity-feeding through a ?ne-bore tube.

A number of proprietary enteral foods are available. Some contain whole protein as the nitrogen source; others – and these are called elemental diets – contain free amino acids. DIARRHOEA is the most common problem with enteral feeding and it tends to occur when enteral feeding is introduced too rapidly or with too strong a preparation.... enteral feeding

Liver

The liver is the largest gland in the body, serving numerous functions, chie?y involving various aspects of METABOLISM.

Form The liver is divided into four lobes, the greatest part being the right lobe, with a small left lobe, while the quadrate and caudate lobes are two small divisions on the back and undersurface. Around the middle of the undersurface, towards the back, a transverse ?ssure (the porta hepatis) is placed, by which the hepatic artery and portal vein carry blood into the liver, and the right and left hepatic ducts emerge, carrying o? the BILE formed in the liver to the GALL-BLADDER attached under the right lobe, where it is stored.

Position Occupying the right-hand upper part of the abdominal cavity, the liver is separated from the right lung by the DIAPHRAGM and the pleural membrane (see PLEURA). It rests on various abdominal organs, chie?y the right of the two KIDNEYS, the suprarenal gland (see ADRENAL GLANDS), the large INTESTINE, the DUODENUM and the STOMACH.

Vessels The blood supply di?ers from that of the rest of the body, in that the blood collected from the stomach and bowels into the PORTAL VEIN does not pass directly to the heart, but is ?rst distributed to the liver, where it breaks up into capillary vessels. As a result, some harmful substances are ?ltered from the bloodstream and destroyed, while various constituents of the food are stored in the liver for use in the body’s metabolic processes. The liver also receives the large hepatic artery from the coeliac axis. After circulating through capillaries, the blood from both sources is collected into the hepatic veins, which pass directly from the back surface of the liver into the inferior vena cava.

Minute structure The liver is enveloped in a capsule of ?brous tissue – Glisson’s capsule – from which strands run along the vessels and penetrate deep into the organ, binding it together. Subdivisions of the hepatic artery, portal vein, and bile duct lie alongside each other, ?nally forming the interlobular vessels,

which lie between the lobules of which the whole gland is built up. Each is about the size of a pin’s head and forms a complete secreting unit; the liver is built up of hundreds of thousands of such lobules. These contain small vessels, capillaries, or sinusoids, lined with stellate KUPFFER CELLS, which run into the centre of the lobule, where they empty into a small central vein. These lobular veins ultimately empty into the hepatic veins. Between these capillaries lie rows of large liver cells in which metabolic activity occurs. Fine bile capillaries collect the bile from the cells and discharge it into the bile ducts lying along the margins of the lobules. Liver cells are among the largest in the body, each containing one or two large round nuclei. The cells frequently contain droplets of fat or granules of GLYCOGEN – that is, animal starch.

Functions The liver is, in e?ect, a large chemical factory and the heat this produces contributes to the general warming of the body. The liver secretes bile, the chief constituents of which are the bile salts (sodium glycocholate and taurocholate), the bile pigments (BILIRUBIN and biliverdin), CHOLESTEROL, and LECITHIN. These bile salts are collected and formed in the liver and are eventually converted into the bile acids. The bile pigments are the iron-free and globin-free remnant of HAEMOGLOBIN, formed in the Kup?er cells of the liver. (They can also be formed in the spleen, lymph glands, bone marrow and connective tissues.) Bile therefore serves several purposes: it excretes pigment, the breakdown products of old red blood cells; the bile salts increase fat absorption and activate pancreatic lipase, thus aiding the digestion of fat; and bile is also necessary for the absorption of vitamins D and E.

The other important functions of the liver are as follows:

In the EMBRYO it forms red blood cells, while the adult liver stores vitamin B12, necessary for the proper functioning of the bone marrow in the manufacture of red cells.

It manufactures FIBRINOGEN, ALBUMINS and GLOBULIN from the blood.

It stores IRON and copper, necessary for the manufacture of red cells.

It produces HEPARIN, and – with the aid of vitamin K – PROTHROMBIN.

Its Kup?er cells form an important part of the RETICULO-ENDOTHELIAL SYSTEM, which breaks down red cells and probably manufactures ANTIBODIES.

Noxious products made in the intestine and absorbed into the blood are detoxicated in the liver.

It stores carbohydrate in the form of glycogen, maintaining a two-way process: glucose

glycogen.

CAROTENE, a plant pigment, is converted to vitamin A, and B vitamins are stored.

It splits up AMINO ACIDS and manufactures UREA and uric acids.

It plays an essential role in the storage and metabolism of FAT.... liver

Lymph

Lymph is the ?uid which circulates in the lymphatic vessels of the body. It is a colourless ?uid, like blood PLASMA in composition, only rather more watery. It contains salts similar to those of blood plasma, and the same proteins, although in smaller amount: FIBRINOGEN, serum albumin (see ALBUMINS), and serum GLOBULIN. It also contains lymphocytes (white blood cells), derived from the glands. In some lymphatic vessels, the lymph contains, after meals, a great amount of FAT in the form of a ?ne milky emulsion. These are the vessels which absorb fat from the food passing down the INTESTINE, and convey it to the thoracic duct; they are called lacteals because their contents look milky (see CHYLE).

The lymph is derived, initially, from the blood, the watery constituents of which exude through the walls of the CAPILLARIES into the tissues, conveying material for the nourishment of the tissues and absorbing waste products.

The spaces in the tissues communicate with lymph capillaries, which have a structure similar to that of the capillaries of the blood-vessel system, being composed of delicate ?at cells joined edge to edge. These unite to form ?ne vessels, resembling minute veins in structure, called lymphatics, which ramify throughout the body, passing through lymphatic glands and ultimately discharging their contents into the jugular veins in the root of the neck. Other lymph vessels commence in great numbers as minute openings on the surface of the PLEURA and PERITONEUM, and act as drains for these otherwise closed cavities. When ?uid is e?used into these cavities – as in a pleural e?usion, for example – its absorption takes place through the lymphatic vessels. The course of these vessels is described under the entry on GLAND.

Lymph circulates partly by reason of the pressure at which it is driven through the walls of the blood capillaries, but mainly in consequence of incidental forces. The lymph capillaries and vessels are copiously provided with valves, which prevent any back ?ow of lymph, and every time these vessels are squeezed (as by the contraction of a muscle, or movement of a limb) the lymph is pumped along.

The term lymph is also applied to the serous ?uid contained in the vesicles which develop as the result of vaccination, and used for the purpose of vaccinating other individuals.... lymph

Nephrotic Syndrome

Nephrotic syndrome is one of PROTEINURIA, hypo-albuminaemia and gross OEDEMA. The primary cause is the leak of albumin (see ALBUMINS) through the GLOMERULUS. When this exceeds the liver’s ability to synthesise albumin, the plasma level falls and oedema results. The nephrotic syndrome is commonly the result of primary renal glomerular disease (see KIDNEYS, DISEASES OF – Glomerulonephritis). It may also be a result of metabolic diseases such as diabetic glomerular sclerosis and AMYLOIDOSIS. It may be the result of systemic autoimmune diseases such as SYSTEMIC LUPUS ERYTHEMATOSUS (SLE) and POLYARTERITIS NODOSA. It may complicate malignant diseases such as MYELOMATOSIS and Hodgkin’s disease (see LYMPHOMA). It is sometimes caused by nephrotoxins such as gold or mercury and certain drugs, and it may be the result of certain infections such as MALARIA and CROHN’S DISEASE.... nephrotic syndrome

Parenteral Nutrition

In severely ill patients – especially those who have had major surgery or those with SEPSIS, burns, acute pancreatitis (see PANCREAS, DISORDERS OF) and renal failure – the body’s reserves of protein become exhausted. This results in weight loss; reduction in muscle mass; a fall in the serum albumin (see ALBUMINS) and LYMPHOCYTE count; and an impairment of cellular IMMUNITY. Severely ill patients are unable to take adequate food by mouth to repair the body protein loss so that enteral or parenteral nutrition is required. Enteral feeding is through the gastrointestinal tract with the aid of a nasogastric tube; parenteral nutrition involves the provision of carbohydrate, fat and proteins by intravenous administration.

The preferred route for the infusion of hyperosmolar solutions is via a central venous catheter (see CATHETERS). If parenteral nutrition is required for more than two weeks, it is advisable to use a long-term type of catheter such as the Broviac, Hickman or extra-corporeal type, which is made of silastic material and is inserted via a long subcutaneous tunnel; this not only helps to ?x the catheter but also minimises the risk of ascending infection.

Dextrose is considered the best source of carbohydrate and may be used as a 20 per cent or 50 per cent solution. AMINO ACIDS should be in the laevo form and should contain the correct proportion of essential (indispensable) and non-essential amino acids. Preparations are available with or without electrolytes and with or without fat emulsions.

The main hazards of intravenous feeding are blood-borne infections made possible by continued direct access to the circulation, and biochemical abnormalities related to the composition of the solutions infused. The continuous use of hypertonic solutions of glucose can cause HYPERGLYCAEMIA and glycosuria and the resultant POLYURIA may lead to dehydration. Treatment with INSULIN is needed when hyper-osmolality occurs, and in addition the water and sodium de?cits will require to be corrected.... parenteral nutrition

Plasma Exchange

Also known as plasmapheresis. The removal of the circulating PLASMA from the patient. It is done by removing blood from a patient and returning the red cells with a plasma expander. The plasma exchange is carried out through an in-dwelling CANNULA in the femoral vein, and the red cells and plasma are separated by a hemonetics separator. Usually a sequence of three or four sessions is undertaken, at each of which 2–3 litres of plasma are removed. The lost plasma can either be replaced by human serum albumin (see ALBUMINS) or a plasma expander.

In autoimmune disorders, disease is due to damage wrought by circulating ANTIBODIES or sensitised lymphocytes (see LYMPHOCYTE). If the disease is due to circulating humoral antibodies, removal of these antibodies from the body should theoretically relieve the disorder. This is the principle on which plasma exchange was used in the management of autoimmune diseases due to circulating antibodies. Such disorders include Goodpasture’s syndrome, SYSTEMIC LUPUS ERYTHEMATOSUS (SLE) and MYASTHENIA GRAVIS. One of the problems in the use of plasma exchange in the treatment of such diseases is that the body responds to the removal of an antibody from the circulation by enhanced production of that antibody by the immune system. It is therefore necessary to suppress this homeostatic response with cytotoxic drugs such as AZATHIOPRINE. Nevertheless, remissions can be achieved in autoimmune diseases due to circulating antibodies by the process of plasma exchange.... plasma exchange

Proteinuria

A condition in which proteins, principally ALBUMINS, are present in the URINE. It is often a symptom of serious heart or kidney disease, although some normal people have mild and transient proteinuria after exercise.

Causes

KIDNEY DISEASE is the most important cause of proteinuria, and in some cases the discovery of proteinuria may be the ?rst evidence of such disease. This is why an examination of the urine for the presence of albumin constitutes an essential part of every medical examination. Almost any form of kidney disease will cause proteinuria, but the most frequent form to do this is glomerulonephritis (see under KIDNEYS, DISEASES OF). In the subacute (or nephrotic) stage of glomerulonephritis, the most marked proteinuria of all may be found. Proteinuria is also found in infections of the kidney (pyelitis) as well as in infections of the bladder (cystitis) and of the urethra (urethritis). PREGNANCY The development of proteinuria in pregnancy requires investigation, as it may be the ?rst sign of one of the most dangerous complications of pregnancy: toxaemia of pregnancy (PRE-ECLAMPSIA and ECLAMPSIA) and glomerulonephritis. Proteinuria may also result from the contamination of urine with vaginal secretions. (See also PREGNANCY AND LABOUR.) CARDIOVASCULAR DISORDERS are commonly accompanied by proteinuria, particularly when the right side of the heart is failing. In severe cases of failure, accompanied by OEDEMA, the proteinuria may be marked. (See also HEART, DISEASES OF.) FEVER often causes proteinuria, even though there is no actual kidney disease. The proteinuria disappears soon after the temperature becomes normal. (See also PYREXIA.) DRUGS AND POISONS These include arsenic, lead, mercury, gold, copaiba, salicylic acid and quinine. ANAEMIA A trace of albumin may be found in the urine in severe anaemia.

POSTURAL OR ORTHOSTATIC ALBUMINURIA

This type is important because, if its true cause is unrecognised, it may be taken as a sign of kidney disease. The signi?cance of postural proteinuria is unclear: it is more common among young people and is absent when the person is recumbent – hence the importance of testing a urine sample that is taken before rising in the morning.

Treatment The treatment is that of the underlying disease. (See KIDNEYS, DISEASES OF.)... proteinuria

Toxins

Poisons produced by BACTERIA. (See also IMMUNITY; IMMUNOLOGY; MICROBIOLOGY.) Toxins are usually soluble, easily destroyed by heat, sometimes of the nature of crystalline substances, and sometimes ALBUMINS. When injected into animals in carefully graduated doses, they bring about the formation of substances called antitoxins which neutralise the action of the toxin. These antitoxins are generally produced in excessive amount, and the SERUM of the animal when withdrawn can be used for conferring antitoxic powers upon other animals or human beings to neutralise the disease in question. The best known of these antitoxins are those of DIPHTHERIA and TETANUS. Toxins are also found in many plants and in snake venom.

Some toxins are not set free by bacteria, but remain in the substance of the latter. They are known as endotoxins and are not capable of producing antitoxins.... toxins

Urine

Waste substances resulting from the body’s metabolic processes, selected by the KIDNEYS from the blood, dissolved in water, and excreted. Urine is around 96 per cent water, the chief waste substances being UREA (approximately 25 g/1), common salt (approximately 9 g/l), and phosphates and sulphates of potassium, sodium, calcium, and magnesium. There are also small amounts of URIC ACID, ammonia, creatinine, and various pigments. Poisons, such as MORPHINE, may be excreted in the urine; and in many infections, such as typhoid fever (see ENTERIC FEVER), the causative organism may be excreted.

The daily urine output varies, but averages around 1,500 ml in adults, less in children. The ?uid intake and ?uid output (urine and PERSPIRATION) are interdependent, so as to maintain a relatively constant ?uid balance. Urine output is increased in certain diseases, notably DIABETES MELLITUS; it is diminished (or even temporarily stopped) in acute glomerulonephritis (see under KIDNEYS, DISEASES OF), heart failure, and fevers generally. Failure of the kidneys to secrete any urine is known as anuria, while stoppage due to obstruction of the ureters (see URETER) by stones, or of the URETHRA by a stricture, despite normal urinary secretion, is known as urinary retention.

Normal urine is described as straw- to amber-coloured, but may be changed by various diseases or drugs. Chronic glomerulonephritis or poorly controlled diabetes may lead to a watery appearance, as may drinking large amounts of water. Consumption of beetroot or rhubarb may lead to an orange or red colour, while passage of blood in the urine (haematuria) results in a pink or bright red appearance, or a smoky tint if just small amounts are passed. A greenish urine is usually due to BILE, or may be produced by taking QUININE.

Healthy urine has a faint aroma, but gives o? an unpleasant ammoniacal smell when it begins to decompose, as may occur in urinary infections. Many foods and additives give urine a distinctive odour; garlic is particularly characteristic. The density or speci?c gravity of urine varies normally from 1,015 to 1,025: a low value suggests chronic glomerulonephritis, while a high value may occur in uncontrolled diabetes or during fevers. Urine is normally acidic, which has an important antiseptic action; it may at times become alkaline, however, and in vegetarians, owing to the large dietary consumption of alkaline salts, it is permanently alkaline.

Chemical or microscopical examination of the urine is necessary to reveal abnormal drugs, poisons, or micro-organisms. There are six substances which must be easily detectable for diagnostic purposes: these are ALBUMINS, blood, GLUCOSE, bile, ACETONE, and PUS and tube-casts (casts from the lining of the tubules in the kidneys). Easily used strip tests are available for all of these, except the last.

Excess of urine It is important to distinguish urinary frequency from increase in the total amount of urine passed. Frequency may be due to reduced bladder capacity, such as may be caused by an enlarged PROSTATE GLAND, or due to any irritation or infection of the kidneys or bladder, such as CYSTITIS or the formation of a stone. Increased total urinary output, on the other hand, is often a diagnostic feature of diabetes mellitus. Involuntary passage of urine at night may result, leading to bed wetting, or NOCTURNAL ENURESIS in children. Diagnosis of either condition, therefore, means that the urine should be tested for glucose, albumin, gravel (fragments of urinary calculi), and pus, with appropriate treatment.... urine


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