An enzyme is a biological catalyst that is not itself destroyed in the conversion process. Enzymes convert organic compounds into simpler substances and are formed by micro-organisms and cells. Research Enzyme
Acetylcholine (Ach) is a chemical that serves as a neurotransmitter, communicating nerve impulses between the cells of the nervous system. It is largely associated with the transmission of impulses across the synapse between nerve and muscle cells, causing the muscles to contract. ACh is produced in the synaptic knob and stored in vesicles until a nerve impulse triggers its discharge across the synapse. When the ACh reaches the membrane of the receiving cell it binds with a specific site and brings about depolarisation - a reversal of the electric charge on either side of the membrane causing a fresh impulse in nerve cells or a contraction in muscle cells. Its action is short-lived because it is quickly destroyed by the enzyme cholinesterase. Anticholinergic drugs have a number of uses in medicine to block the action of ACh, thereby disrupting the passage of nerve impulses and relaxing certain muscles, for example in premedication before surgery. Research Acetylcholine
The acrosome is a thin cap of protoplasm encasing the head of a sperm. The acrosome is believed to contain an enzyme, hyaluronidase, that dissolves the coronaradiata, the protective outer coat of the ovum, making sperm penetration easier. The enzyme of the acrosome of one sperm is insufficient to break down the ovummembrane. Therefore, contrary to popular opinion, it takes more than one spermatozoon to produce a baby. Only one sperm, however, will actually penetrate the egg. Research Acrosome
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
Aldose reductase inhibitors are a class of drugs believed to prevent eye and nerve damage in people with diabetes. Aldose reductase is an enzyme that is normally present in the eye and in many other parts of the body. It helps change glucose into the sugar alcohol sorbitol. Too much sorbitol trapped in eye and nerve cells can damage these cells, leading to retinopathy and neuropathy. Drugs that prevent or slow the action of aldose reductase are a possible way to prevent or delay these complications of diabetes. Research Aldose Reductase Inhibitor
The corona radiata is a group of follicular cells surrounding the zona pellucida. It is the gelatinous protective outer coat of the ovum. The thin cap surrounding the head of the sperm, called the acrosome, contains the enzyme hyaluronidase, which is capable of dissolving the corona radiata enabling sperm penetration. Research Corona Radiata
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
Jaundice is a yellowing of the skin, conjunctivae, and mucous membranes caused by excessive amounts of bile pigments in the blood tissues. These pigments, normally present in blood as a result of the breakdown of haemoglobin in red blood cells, are filtered through the liver and excreted. Excessive amounts of these pigments produce four types of jaundice. In haemolytic jaundice there is increased production of bile pigment because of red blood-cell damage. This damage can be caused by antibodies created by a mismatched blood transfusion. In infants the antibodies can be caused by prenatal mismatch between the Rhfactor in the infant' s blood and that of the mother. Newborns can also be jaundiced as a consequence of the condition known as hyperbilirubinemia. In these cases, there is a temporary defect in synthesis of the enzyme that breaks down bile to an excretable form. Hepatocellular jaundice occurs when liver cells are damaged either by viruses or by excessive intake of alcohol and lose the ability to filter pigment. Obstructive jaundice
follows physical obstruction of the ducts that transport pigment from the liver to the intestine. Blockage can be due to gallstones, tumour, or inflammation. Research Jaundice
The kidneys are two, bean-shaped organs are located in the posterior of the abdomen. They generally are not thought of as endocrine organs.
The major function of the kidneys is the filtering toxins, wastes, ingested water, and mineral salts out of the bloodstream. However, the kidneys also serve a number of important endocrine functions.
They produce a substance called renin, which is an important enzyme in controlling blood pressure. When blood pressure falls, the kidneys release renin, which converts angiotensisnogen to the protein angiotensin I. This protein is then converted to angiotensin II,a protein which constricts blood vessels and thereby increases blood pressure. Angiotensis II also stimulates the release of aldosterone, a hormone that increases blood pressure.
Abbreviations
Research Enzyme
