Albumin is one of the three main components of plasma. The other two proteins are globulins and fibrinogen. All three proteins are manufactured by the liver. These three proteins circulate in plasma and act as carriers for small molecules. Albumin, the most plentiful, is similar in texture to egg whites and gives blood its gummy texture. It is soluble in water and coagulable by heat. The globulins, three in number: alpha, beta, and gamma. They are divided on the basis of electrophoretic mobility. The globulins transport certain proteins. They number half the albumin proteins found in plasma. The globulin proteins are insoluble in water, soluble in saline solutions, and coagulable by heat. Globulins are also found in cerebrospinal fluid. Gamma globulins are the antibodies of the blood, giving immunity to disease. Only 3% of plasma is made up of fibrinogen. It is an important link in the chain of reactions that leads to blood clotting (coagulation). It uses the enzyme thrombin to form a web of fine protein fibres, called fibrin, that bindblood cells together, creating a bridge over which injured tissue can rebuild itself while blood continues to flow underneath. As an important factor to coagulation, it is often referred to as factorI. Research Albumin
Fibrinogen is one of the three main components of plasma. The other two being globulins and albumin. Only 3% of plasma is made up of fibrinogen. It is an important link in the chain of reactions that leads to blood clotting. It uses the enzyme thrombin to form a web of fine protein fibres, called fibrin, that bindblood cells together, creating a bridge over which injured tissue can rebuild itself while blood continues to flow underneath. As an important factor to coagulation, it is often referred to as factorI. Research Fibrinogen
Platelets are tiny specialized cells that are activated whenever blood clotting or repair to a vessel is necessary. Although they are often called cells, they are really fragments of other cells. They are made in bonemarrow and are much smaller than red blood cells. A drop of blood contains some 15 million platelets. When a blood vessel is cut, platelets rush to the vessel and swell into odd, irregular shapes, grow sticky and clog at the cut, creating a plug. If the cut is too large for platelets, they send out signals to initiate clotting by releasing a hormone called serotonin, which stimulates blood vessels to contract thus reducing the flow of blood. Clotting is fundamentally a change of the soluble plasmaproteinfibrinogen into an insoluble, thread-like protein, called fibrin. More than a dozen factors are involved in this conversion. The fibrin strands mesh around the blood cells and then contract, squeezing a clear yellowish fluid called serum, and forming a solid clot. Clotting staunches bleeding and creates a scaffold on which to build new tissue. Research Platelets
There are several methods of controlling bleeding during surgical operations. 1. When an incision is made, much of the bleeding comes from the skin edges and from subcutaneous tissue: small towels are often used, clipped to the edges of the wound to protect the cut surface, and prevent the repeated rubbing away of clot which would otherwise occur. These are called variously 'side-towels','skin towels' or 'tetra towels'. The latter term arose as these towels are commonly attached with four- pronged forceps ('tetra forceps'). 2. By pressure. As the surgeon makes his incision, he or his assistant applies a gauze swab to the raw area. Capillary and most venous bleeding stops almost immediately, and does not re-start unless the surface is rubbed. 3. Pressure forceps (arteryforceps) are applied to the cut ends of arteries, as little of the surrounding tissue as possible being included in the jaws of the forceps.
These bleeding points are dealt with at some later stage in the operation in one of four ways. (i) The arteryforceps are simply removed. Bleeding does not recur as the crushed end of the vessel has sealed itself off. (ii) Surgical diathermy current is applied to the pressure forceps, thus coagulating the end of the blood vessel. (iii) A surgical ligature is tied round the tissue included in the forceps which are then removed. (iv) A stitch is inserted and tied round the tissue held in the forceps in order to secure more firmly the end of the cut vessel. 4. The surgical diathermy is used to make the incision through the muscle and deep tissue layers. This technique is used especially in the treatment of cancer and particularly in the removal of vascular structures such as the breast. Small blood vessels are thus sealed as the tissue is divided. 5. The application of gauze soaked in adrenaline solution. This drug constricts the ends of the vessels and is particularly useful in the nose.
Where extensive bleeding may be expected - such as in plastic operations on the face - the operation area is sometimes infiltrated with a saline solution of adrenaline. By the time the effect of the adrenaline has passed off, the divided vessels have become blocked by clots. 6. The application of hot packs. The combination of pressure and heat speeds the clotting process and the retraction of the cut ends of vessels. 7. Thromboplastin released by enzymes from damaged tissue is essential to start the clotting process. There is very little damage in a clean surgical incision and thromboplastin formation can be brought about by the surgeon taking a small piece of muscle, and pulping it by repeated crushing with pressure forceps. This ' muscle graft' is applied to the bleeding area. Purified thrombin is supplied in powder in sterile ampoules ready to mix with sterile water: the solution is then applied with a swab or a spray and is particularly useful under skin grafts where it acts as a kind of glue. Fibrin foam is another preparation used extensively in neurosurgery where even a small amount of bleeding into the brain or nerve, may do irreparable damage. Gelatin 'sponge' supplied in small biscuit-like strips, can be used in bleeding cavities or tied to the surface of a bleeding organ. The sponge acts as an artificial network in which clotting occurs and the substance is itself absorbed.
Oxycel (oxidised cellulose) acts in a similar way and promotes rapid clotting. It is used in such sites as the prostatic cavity and can be tied around the catheter which is left in place at the end of operation. Calciumalginate is a similar preparation and is manufactured from sea-weed. The raw oozing surface is moistened with one solution which is then activated by spraying with a second solution containing calcium. All these artificial coagulants are only of use for 'low pressure' bleeding - that is from capillaries or small veins. Research Surgical Haemostasis
When any portion of body tissue has been destroyed by disease or violence, the adjacent tissues at once set to work to repair the gap. Clearly their task will depend on the extent of the gap and the presence of any factors which hinder normal tissue activity. When a clean surgical incision has been made and the edges sewn closely together the gap to be bridged is very thin. On the other hand, if there has been an abscess and a large area of tissue has been dissolved away, the problem is very much greater. There are many factors which infuence the rate of the body's power of healing. Where a gap has been left in the tissues, the 'raw' surfaces are covered with blood clot and any intervening cavity may in fact be filled with blood. From the ends of the capillaries which have been cut on either side, cells grow rapidly into this haematoma (a collecion of blood in the tissues) and form granulation tissue, which is thus a mass of tiny little capillary buds with fibrous tissue cells.
As the days go by, the very rich blood supply enables fibrous tissue to grow rapidly and become more dense, and finally to cement the gap. Weeks later the blood vessels die off and firm fibrous tissue (scartissue) remains. This becomes slowly tighter and tighter. This process we know as contraction, so that what may appear to be quite a large scar shrinks down over a period of months to become sometimes invisible. Perhaps the best example of this is the cavity left by the removal of the slough from a large carbuncle; in a very few months there is a small white, irregular scar marking the centre of the great cavity where the carbuncle existed. If the wound has involved other tissues than connective tissue - for instance, the mucousmembrane of the cheek, or the skin - then the very specialised epithelial lining also grows across as a sheet of cells and covers up the granulation tissue. The same process occurs in the intestinal tract; when an anastomosis (artificial opening between two hollow organs or vessels) has been performed, the cut edges of the mucousmembrane are stuck together temporarily by fibrin, and over a period of days the cells lining the stomach or intestine grow rapidly across the gap. When a bone is broken, repair takes place in a similar way: calcium substances from the blood are deposited in the granulation tissue forming callus. Into this callus the specialised cells which form true bone, migrate from the surrounding damaged bone: over a period of weeks or even months the minute structure is rebuilt to join up exactly with the bone on either side of the break.
The healing power of the body is influenced by many factors. An adequate supply of oxygen is necessary for these tissue repairs, and as oxygen is carried to the tissues by the blood, anaemia results in a very poor healing rate. Vitamins, especially vitamin C, are necessary for the repair of tissues, so that patients whose reserve of vitamin C has been depleted heal more slowly and may in fact not heal at all. Patients who are ill use more vitamin C than the normal healthy individuals and sometimes, unless their requirement is met, a wound may come apart even a week or more after operation, showing no sign of healing whatever. Infection always delays healing as it interferes with the activities of the cells at the edges of the wound. Similarly, if the patient' s general health has been impaired by longstanding disease or bad nourishment his powers of healing are poor, as the substances required for the repair are in short supply. The presence of foreign bodies or a poor blood supply (such as occurs in arteriosclerosis, or if the stitches have been tied too tight) will also delay sound healing. In addition, there are many personal and undetermined factors which must be responsible for the fact that some people heal quickly and others heal very poorly. Age is important; babies and children repair their tissues very much more rapidly than old people. This is because the growing child has much more vitality in all his cells. For example, a fracture of the humerus in a new-born baby may be soundly united in ten days; in an adult the same fracture requires about eight weeks to heal. Research Tissue Repair and Replacement
Casein is a protein found in milk. It can be separated by the action of acid, the enzyme rennin, or bacteria (souring); it is also the main protein in cheese. Casein is used as a protein supplement in the treatment of malnutrition and is used commercially in cosmetics, glues, pigments and as a sizing for coating paper. Casein is insoluble in water, but is freely soluble in alkaline solutions. Casein is neither coagulated spontaneously, like fibrin, nor by heat, like albumen, but by the action of acids alone, and constituting the chief part of the nitrogenized matter contained in it. Cheese made from skimmed milk and well pressed is fully half casein. Casein is one of the most important elements of animal food as found in milk and leguminous plants. Research Casein
The Probert Encyclopaedia was designed, edited and programed by
Matt and Leela Probert
Abbreviations
Research Albumin
