Diabetes Glossary Terms: E-G

ductless glands that produce hormones for secretion directly into the bloodstream (or lymph). Some organs, e.g. the pancreas, also release secretions via a duct. In addition to the pancreas, the major endocrine glands are the thyroid, pituitary, parathyroid, ovary and testis. Imbalances in the secretions of endocrine glands produce a variety of diseases.

any protein molecule that acts as a catalyst in the biochemical processes of the body. They are essential to life and are highly specific, acting on certain substrates at a set temperature and pH. Examples are the digestive enzymes amylase, lipase and trypsin. Enzymes act by providing active sites (one or more for each enzyme) to which substrate molecules bind, forming a short-lived intermediate. The rate of reaction is increased, and after the product is formed, the active site is freed. Enzymes are easily rendered inactive by heat and some chemicals. They are vital for the normal functioning of the body, and their lack or inactivity can produce metabolic disorders.

an inherited disorder that is caused by degeneration of nerve cells in the brain and spinal cord. It appears in children, usually in adolescence, and the symptoms include unsteadiness during walking and a loss of the knee-jerk reflex action, leading progressively to tremors, speech impairment and curvature of the spine. The symptoms are increasingly disabling and may also be accompanied by heart disease.

death of tissue because of loss of blood supply or bacterial infection. There are two types of gangrene, dry and moist. Dry gangrene is caused purely by loss of blood supply and is a late-stage complication of diabetes mellitus in which atherosclerosis is present. The affected part becomes cold and turns brown and black and there is an obvious line between living and dead tissue. In time the gangrenous part drops off.

the fundamental unit of genetic material found at a specific location on a chromosome. It is chemically complex and responsible for the transmission of information between older and younger generations. Each gene contributes to a particular trait or characteristic. There are more than 100,000 genes in humans, and gene size varies with the characteristic, e.g. the gene that codes for the hormone insulin is 1,700 base pairs long. There are several types of gene, depending on their function, and in addition genes are said to be dominant or recessive. A dominant characteristic is one that occurs whenever the gene is present, while the effect of a recessive gene (e.g. a disease) requires that the gene be on both members of the chromosome pair, i.e. it must be homozygous.

an organ or group of cells that secretes a specific substance or substances, e.g. hormones. Endocrine glands secrete directly into the blood, while exocrine glands secrete on to an epithelial surface via a duct. Some glands produce fluids, for example, milk from the mammary glands, saliva from the sublingual gland. The thyroid gland is an endocrine gland that releases hormones into the bloodstream. A further system of glands, the lymphatic glands, occurs throughout the body in association with the lymphatic vessels.

one of a group of globular proteins that occur widely in milk, blood, eggs and plants. There are four types in blood serum: al, a2, b and g. The alpha and beta types are carrier proteins, like haemoglobin, and gamma globulins include the immunoglobulins involved in the immune response.

a hormone important in maintaining the level of the body's blood sugar. It works antagonistically with insulin, increasing the supply of blood sugar through the breakdown of glycogen to glucose in the liver. Glucagon is produced by the islets of Langerhans when blood-sugar level is low.

a carbohydrate (polysaccharide) stored mainly in the liver. It acts as an energy store that is liberated upon hydrolysis.

the presence of sugar (glucose) in the urine, which is usually because of diabetes mellitus.

a disorder typified by thyroid gland overactivity, an enlargement of the gland and protruding eyes. It is caused by antibody production and is probably an autoimmune response. Patients commonly exhibit excess metabolism (because thyroid hormones control the body's metabolism), nervousness, tremor, hyperactivity, rapid heart rate, an intolerance of heat, breathlessness, and so on. Treatment may follow one of three courses: drugs to control the thyroid's production of hormones; surgery to remove part of the thyroid; or radioactive iodine therapy.

a hormone produced and stored by the anterior pituitary gland that controls protein synthesis in muscles and the growth of long bones in legs and arms. Low levels result in dwarfism in children. Overproduction produces gigantism in children, and acromegaly in adolescents.