Контрольные тексты по Английскому языку в IV семестре (некоторые варианты) Вариант 1

Unlike a simple liquid, such as water, or a simple solution, such as salt water, blood is a complex fluid made up of several components each of which is, in turn, extremely complex and even today not fully understood. Many of these substances are solids in suspension. Unlike most simple liquids that are not easily changed when exposed to air or to slight alterations in their environment, the physical and biochemical properties of blood undergo marked changes (Hemostatic responses) when blood is taken from the body's circulatory system and, for example, placed in a test tube. Separation of blood from its usual environment immediately initiates biochemical processes which alter its properties and cause it to release its components. When so removed, blood shortly becomes viscid and forms a soft, jellylike substance, then soon separates into a firm solid mass (clot) and liquid (serum). This extremely important property of clotting is unique to blood among known inorganic and organic fluids and solutions. Were it not for this property, a person would bleed (hemorrhage) to death if a blood vessel were opened by accident or as the consequence of disease. Thus, blood may be described as a living fluid and most accurately as living tissue, like the other tissues of the body.

Вариант 2

While the malignant cells circular in the blood they undergo a variety of important cellular interactions.

These interactions are likely to affect the survival of the cells and their arrest in the capillaries. The circulating malignant cells can, for example, adhere to other tumor cells to form clumps. They can adhere to such normal blood cells as lymphocytes and platelets. And when they enter a capillary bed, they can adhere to the endothelial cells that line the vessels. The larger the clump is, the more likely it is to become arrested in the capillaries and ultimately mately form a new tumor colony. Having been arrested in the capillaries, some blood-borne tumor cells stimulate the production of fibrin, the fibrous protein that is ordinarily involved in the formation of blood clots.

Once the malignant cells are arrested in small venules or capillaries, they must get through the blood-vessel wall and into the tissue outside it in order to survive. Once the tumor cells have invaded the extra vascular tissue a new microenvironment must be established. The growth of the new tumor colony is limited until a new blood supply becomes available to deliver nutrients and carry away cellular waste products.

Вариант 3

A very common form of ulcer in the gut is the Peptic ulcer, and at least one person in twenty is likely to have one at some time in their lives. Peptic ulcers are found in the stomach itself, when they are sometimes called gastric ulcers, but may occur in the adjacent part of the small intestine - the duodenum - when they are called duodenal ulcers. Duodenal ulcers are more common than the gastric variety, largely because the stomach secretes a much more effective layer of mucus to protect itself against its own acid.

Peptic ulcers have long been thought to be produced by generalized stress, alcohol, eating spicy foods, and many other factors for which there is no convincing scientific evidence. Stress may be involved, particularly in situations in which the individual feels alone and isolated, with no one to share me problems, and in situations in which there appears to be no obvious solution to a problem. More recently, however, a particular type of bacterium has been shown to play a major role in peptic ulceration. It is called Helicobacter pylori and if eliminated with antibiotics many ulcers heal and do not recur

Whatever the cause, a major reason for the pain and discomfort of peptic ulcers is that the acid produced by the stomach irritates the exposed surfaces of me ulcer.