Globin Health Dictionary

Globin: From 2 Different Sources


A protein which, when it combines with haem, forms HAEMOGLOBIN – the molecule found in the red blood cell that carries oxygen and carbon dioxide.
Health Source: Medical Dictionary
Author: Health Dictionary
n. a protein, found in the body, that can combine with iron-containing groups to form *haemoglobin (which is found in red blood cells) and *myoglobin (found in muscle).
Health Source: Oxford | Concise Colour Medical Dictionary
Author: Jonathan Law, Elizabeth Martin

Haemoglobin

The colouring compound which produces the red colour of blood. Haemoglobin is a chromoprotein, made up of a protein called globin and the iron-containing pigment, haemin. When separated from the red blood corpuscles – each of which contains about 600 million haemoglobin molecules – it is crystalline in form.

Haemoglobin exists in two forms: simple haemoglobin, found in venous blood; and oxy-haemoglobin, which is a loose compound with oxygen, found in arterial blood after the blood has come into contact with the air in the lungs. This oxyhaemoglobin is again broken down as the blood passes through the tissues, which take up the oxygen for their own use. This is the main function of haemoglobin: to act as a carrier of oxygen from the lungs to all the tissues of the body. When the haemoglobin leaves the lungs, it is 97 per cent saturated with oxygen; when it comes back to the lungs in the venous blood, it is 70 per cent saturated. The oxygen content of 100 millilitres of blood leaving the lungs is 19·5 millilitres, and that of venous blood returning to the lungs, 14·5 millilitres. Thus, each 100 millilitres of blood delivers 5 millilitres of oxygen to the tissues of the body. Human male blood contains 13–18 grams of haemoglobin per 100 millilitres; in women, there are 12–16 grams per 100 millilitres. A man weighing 70 kilograms (154 pounds) has around 770 grams of haemoglobin circulating in his red blood corpuscles.... haemoglobin

Haem

A compound that contains iron and which combines with globin to form haemoglobin.... haem

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

Haemoglobinopathy

A term used to describe the genetic disorders in which there is a fault in the production of the globin chains of haemoglobin.

Examples of haemoglobinopathies include sickle cell anaemia and the thalassaemias.... haemoglobinopathy

Anaemia: Sickle Cell

A form of anaemia growing into an acute social problem, affecting people of African, Asian, and Mediterranean origin. Thalassaemias are caused by defects of a gene that produces the globin part of haemoglobin. Such defects in the DNA can now be detected in the womb before birth. The name derives from sickle-shaped cells instead of circular red blood cells. Few sufferers survive beyond their 40th year.

Symptoms. Unhealthy pallor, listlessness, sore tongue, dizziness, vague aches and pains, rapid pulse and breathing, tinnitus, palpitation. The skull may be disproportionately large, resistance to infection feeble, chances of survival poor. This form of anaemia is linked with defective colour vision. Impaired liver function. Stunted growth, great pain. Sufferers have a higher risk of infection.

Malaria. Sufferers are less likely to die of malaria because their red cells do not support the growth of malaria parasites very well.

Carriers: Carriers of the sickle-cell gene can now be identified by a simple blood test.

Treatment. No specifics exist but supportive herbal treatment has been known to increase output of red cells and raise haemoglobin levels:– Red Clover flowers, Yellow Dock, Echinacea, Burdock, Wild Indigo, Gentian, Nettles, Birch leaves, Sage, Walnut leaves, Centaury, Gota Kola (Indian Pennywort). Alternatives:– Tea. Mix equal parts: Iceland Moss, Nettles, Red Clover flowers. 2 teaspoons to each cup boiling water; infuse 15 minutes; 1 cup morning and evening.

Decoction. Mix equal parts; Echinacea, Walnut leaves, Balm of Gilead buds; 1 teaspoon to each cup water gently simmered for 20 minutes. Half-1 cup, cold, 3 times daily, before meals.

Tablets/capsules. Sarsaparilla. Ginseng. Iceland Moss. Red Clover. Echinacea. Gentian.

Powders. Formula: Echinacea 1; Fringe Tree half; Ginseng half; White Poplar bark 1. Dose: 500mg (two 00 capsules or one-third teaspoon) thrice daily before meals.

Liquid extracts. Formula. Echinacea 2; Dandelion 1; Oat Husk (avena sativa) 1. Mix. Dose, 1-2 teaspoons before meals, in water or one of the above teas or decoctions.

Tinctures. Same combination. Dose: 2-3 teaspoons.

Dong quai. See entry.

Pollen. Claimed to be of value.

Diet. Dandelion coffee. Molasses. Desiccated liver. Calf liver, fresh. Green leafy vegetables contain chlorophyll, iron and folic acid. Cider vinegar. Dried beans, apricots and shellfish. Dandelion leaves in salads. Milk, eggs, meats, Soya. Carrot juice to increase red cells.

Supplements. Daily. Vitamin B12. Vitamin C, 1g; Folic acid 400mcg, Floradix. Of particular value: Vitamin E 400iu. Zinc.

Note: Those at risk should submit themselves for screening. The disease cannot be cured but can be controlled largely by orthodox measures and sometimes by natural medicine. ... anaemia: sickle cell

Thalassaemia

A group of inherited blood disorders in which there is a fault in the production of haemoglobin. Many of the red blood cells become fragile and haemolyse (break up), leading to anaemia (see anaemia, haemolytic). Thalassaemia is prevalent in the Mediterranean, the Middle East, and Southeast Asia, and in families originating from these areas.

Normal adult haemoglobin contains 2 pairs of globins (protein chains): alpha and beta. In thalassaemia, a recessive defective gene results in reduced synthesis of 1 of the chains. Usually beta-chain production is disturbed (beta-thalassaemia). Beta-thalassaemia minor (thalassaemia

trait), which is never severe, is caused by 1 defective gene. The presence of 2 defective genes causes beta-thalassaemia major (Cooley’s anaemia). The much rarer disorder alpha-thalassaemia varies in severity; alpha-thalassaemia major usually results in fetal death.

Symptoms of beta-thalassaemia major appear 3–6 months after birth. If untreated, bone marrow cavities expand, leading to a characteristic enlargement of the skull and facial bones.

Beta-thalassaemia major is diagnosed from microscopic examination of the blood, and from other blood tests. Treatment is with blood transfusions and, sometimes, splenectomy. However, successive blood transfusions cause a buildup of iron in the body (see haemosiderosis). Chelating agents are given by continuous infusion to help the body excrete the excess iron. A bone marrow transplant offers a cure for the disease.

Genetic counselling is advised for parents or other close relatives of a child with thalassaemia, and also for any person with thalassaemia trait.... thalassaemia




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