Sugar Metabolism: GLYCEMIA AND GLYCOSURIA

-
If the body produces too much pituitary hormone or too little insulin, the amount of sugar in the blood rises abnormally, producing a condition known as hyperglycemia. In hyperglycemia the blood may contain as much as four times the normal amount of sugar. Hyperglycemia in itself is not lethal, but it is a symptom of a serious disease, diabetes mellitus. Diabetes is sometimes caused by a tumor or other condition in the pancreas that prevents the formation of insulin. Diabetic patients do not die of hyperglycemia, but if they are not given injections of insulin they may die from such causes as the accumulation of poisons in the body, produced by altered metabolism of fats; the body of the diabetic consumes fats as a substitute for the sugar that it cannot use.

If an excessive amount of insulin is injected into the body, the amount of sugar is reduced to a dangerously low level, a condition known as hypoglycemia or insulin shock. Controlled insulin shock is sometimes used in the treatment of certain types of mental illness.

In a normal individual, if the amount of sugar in the blood rises abnormally, the excess is removed from the blood by the kidneys and excreted in the urine. The presence of sugar in the urine is called glycosuria, and although it is an important symptom of diabetes, it is not always found in diabetic patients; moreover, glycosuria may appear in normal individuals immediately after a large meal. The critical test for diabetes is neither hyperglycemia nor glycosuria, but blood-sugar tolerance: after ingesting sugar, both normal and diabetic individuals show an increased percentage of blood sugar; the percentage remains high in the diabetic, whereas in the normal individual the excess glucose is rapidly converted into glycogen.

More Articles:



Popular posts from this blog

Cellular Respiration

-
Cellular Respiration, process in which cells produce the energy they need to survive. In cellular respiration, cells use oxygen to break down the sugar glucose and store its energy in molecules of adenosine triphosphate (ATP). Cellular respiration is critical for the survival of most organisms because the energy in glucose cannot be used by cells until it is stored in ATP. Cells use ATP to power virtually all of their activities—to grow, divide, replace worn out cell parts, and execute many other tasks. Cellular respiration provides the energy required for an amoeba to glide toward food, the Venus fly trap to capture its prey, or the ballet dancer to execute stunning leaps. Cellular respiration occurs within a cell constantly, day and night, and if it ceases, the cell—and ultimately the organism—dies. Two critical ingredients required for cellular respiration are glucose and oxygen. The glucose used in cellular respiration enters cells in a variety of ways. Plants, algae, and cer
Read more

The Human Eye

-
Image
Structure of the Eye The amount of light entering the eye (right) is controlled by the pupil, which dilates and contracts accordingly. The cornea and lens, whose shape is adjusted by the ciliary body, focus the light on the retina, where receptors convert it into nerve signals that pass to the brain. A mesh of blood vessels, the choroid, supplies the retina with oxygen and sugar. Lacrimal glands (left) secrete tears that wash foreign bodies out of the eye and keep the cornea from drying out. Blinking compresses and releases the lacrimal sac, creating a suction that pulls excess moisture from the eye’s surface. The entire eye , often called the eyeball, is a spherical structure approximately 2.5 cm (about 1 in) in diameter with a pronounced bulge on its forward surface. The outer part of the eye is composed of three layers of tissue. The outside layer is the sclera, a protective coating. It covers about five-sixths of the surface of the eye. At the front of the eyeball, it is continuo
Read more

Respiratory System

-
. Respiratory System, in anatomy and physiology, organs that deliver oxygen to the circulatory system for transport to all body cells. Oxygen is essential for cells, which use this vital substance to liberate the energy needed for cellular activities. In addition to supplying oxygen, the respiratory system aids in removing of carbon dioxide, preventing the lethal buildup of this waste product in body tissues. Day-in and day-out, without the prompt of conscious thought, the respiratory system carries out its life-sustaining activities. If the respiratory system’s tasks are interrupted for more than a few minutes, serious, irreversible damage to tissues occurs, followed by the failure of all body systems, and ultimately, death. While the intake of oxygen and removal of carbon dioxide are the primary functions of the respiratory system, it plays other important roles in the body. The respiratory system helps regulate the balance of acid and base in tissues, a process crucial for the norma
Read more