Dysfunction of carbohydrate metabolism regulations.
For the unremitting of the process of glycolysis and Crab’s cycle glucose should be delivered continuously to the tissues. It happens because of a constant level of glucose (3.3-5.5mmol/lit) in the blood which in physiological conditions never decreases to a critical level. Glucose level in the blood can be identified by the speed of endogenic glucose production and by the speed of glucose utilization. Several types of regulation of carbohydrate metabolism can be distinguished: substrate, nervous, hormonal and renal.
Disturbances of any stage of carbohydrate metabolism or of regulating mechanism cause dysfunction of carbohydrate metabolism and it appears with the change of glucose concentration in blood (hypo- or hyperglycemia).
Hypoglycemia occurs when the concentration of glucose in blood is less than 3.3 mmol/lit. It requires an immediate treatment, because hypoglycemia causes irreversible changes of the nervous cells, first it disturbs the function of the cortical layer of the brain then in the midbrain (cereal hypoglycemia).
Hyperglycemia occurs when the concentration of glucose in blood is more than 5.5mmol/lit.
It can be divided into: physiological hyperglycemia (it has an accommodative function as it provides easy utilizing energy material by tissues), alimentary hyperglycemia (occurs after eating of a great amount of carbohydrate), emotional hyperglycemia (develops due to stress, emotional excitement, severe pains), hormonal hyperglycemia (is caused by the dysfunction of endocrine glands).
2. Выразите смысл каждого абзаца одним или двумя предложениями.
3. Ответьте на следующие вопросы:
1. Why should glucose be delivered to the tissues continuously?
2. How can glucose level in the blood be identified?
3. What types of carbohydrate metabolism can be distinguished?
4. When does hyperglycemia occur?
5. Why does hyperglycemia require immediate treatment?
4. Сделайте краткий пересказ, выбрав из текста ключевую информацию.
1. Прочитайте и переведите текст, используя следующие слова:
agent - фактор, вещество
deleterious response - разрушительная реакция
to be subjected to - подлежать; подвергаться
artificial - искусственный
to be categorized - быть распределенным
with respect to - относительно
venom - яд животного происхождения
snake - змея
marine - морской
hazard - губительное действие
algae - водоросли
solvent - растворитель
target - мишень
lead - свинец
All substances are poisons; there is
none which is not a poison. The right
dose differentiates a poison and a
One could define a poison as any agent that is capable of producing a deleterious response in a biological system or capable of destroying life or seriously injuring function.
The origins of toxic substances are varied and subjected to several kinds of classification. At its simplest one can recognize those agents that arise from natural sources and those that are artificial or synthetic. Naturally occurring substances may be categorized with respect to their origin from animal, plant or mineral sources. Venoms and toxins in structured organs of the snake and marine animals represent one kind of well-known animal source of toxic substances. Terodotoxin and other toxic substances found in fish, derive from other marine organisms that are components of the fish diet.
Among the higher plants there are numerous species that contain toxic agents. Many of the better-known and best-characterized substances are those that have been adopted or developed for medicinal use. A few prominent examples are opium and morphine, atropine, cardiac glycosides, salicylate, quinine, physostigmine, scopolamine, reserpine, cocaine, picrotoxin and curare.
Lower plants are also a source of many toxic agents. We make use of a selective toxicity of some of these substances as antibiotic agents in medicine. But many organisms produce toxins that represent hazards to health. For example, bacterial endotoxins of Salmonella and Botulinusare well known poisons.
Marine organisms such as Gymodmium brevaehave resulted in major ecologic disasters; similar effects have been noted with some of the blue-green algae.
Most often chemical classification at several levels is used. Thus we might list solvents, metals, plastics and many similar groups.
Other classifications are based on the organs or systems that are the “target” site for the effects of the chemical (for example, hepatotoxic). Whatever classification is selected, it is not full.
After the toxicant enters the plasma, either by absorption or by direct intravenous administration, it is available for distribution throughout the body. Its distribution is largely dependent on its ability to pass cell membranes and on its affinity for various body components. Some toxicants accumulate in various parts of the body.
Toxicants are often concentrated in a specific tissue. Some toxicants achieve their highest concentration at their site of toxic action, such as carbon monoxide, which has a very high affinity for hemoglobin.
The liver and the kidney have a high capacity to bind chemicals, and these two organs probably concentrate more toxicants than any other organs. This might be related to the fact that these two organs are very important in the elimination of toxicants from the body; the kidney and the liver have a capacity to excrete many chemicals and the liver has a high capacity to metabolize them.
As an example of the rapidity with which liver binds foreign compounds, 30 minutes after a single administration of lead, the concentration is 50 times higher than in the plasma.
Lipid solubility is an important factor for the absorption of toxicants; so it is not surprising that they distribute into body fat. The highest concentration of DDT is found in fat.
Bone can also serve as a reservoir for compounds such as lead and tetracyclines. Approximately 90% of the lead in the body is found in the skeleton. The toxic material deposited in bone is not toxic as such, but it can be released again into the general circulation.
2. Найдите в тексте информацию о:
- origins of toxic substances;
- poisons found in the higher and lower plants;
- other classifications of the poisonous chemicals;
- the role of the liver and kidneys in the elimination of toxins;
- the role of lipids and bones in the purification of the body.
3. Согласитесь или отрицайте информацию. Дайте обоснование своего ответа, пользуясь
I don’t think so, because… Yes, I agree that …
- One could define a poison as any agent that is capable of destroying life or seriously injuring its functions.
- The origins of toxic substances are not varied.
- Some agents arise from natural sources, others are artificial or synthetic.
- Venoms and toxins in structural organs of the snake and marine animals do not represent one kind of a well-known animal source of toxic substances.
- Among the higher plants few species contain toxic agents.
- The lower plants are also a source of many toxic agents.
- Solvents, metals, plastics and many similar groups are not subjected to chemical classification.
- After the toxicant enters the plasma, it is available for distribution throughout the body.
- Toxicants are not concentrated in a specific tissue.
- Some toxicants do not achieve their highest concentration at their site of toxic action.
- The liver and the kidney have a high capacity to bind chemicals, and these two organs concentrate more toxicants than any other organs.
- Lipid solubility is an important factor for the absorption of toxicants.
- Bone cannot serve as a reservoir for compounds such as lead and tetracycline.
- The toxic material deposited in the bone is not toxic as such. It cannot be released again into the general circulation.
4. Расскажите на английском языке о:
1) Classification of the poisonous substances (venoms, toxins, chemicals);
2) Sources of toxins (animals, snakes, fish, plants, artificial sources);
3) The ways the toxicants penetrate into the body;
4) Tissues where toxicants concentrate, and deteriorations caused by them.
Grammar: Revision of Tenses and Voices.
1. Прочитайте слова из Vocabulary List вслух:
- назовите термины, указывающие на разделы аннотации;
- назовите слова, относящиеся к действию лекарств на системы и органы.
composition /description - название препарата, его химический состав
indication - показание к применению
contraindication - противопоказание по применению
precautions / warnings - меры предосторожности
interaction - взаимодействие с другими препаратами
storage - хранение препарата
supply - форма поставки
microbiology - микробиология
biological studies - биологические исследования
animal pharmacology - действие на животных
human pharmacology - действие на человека
clinical studies - клинические исследования
hemopoetic reaction - гемопоэтическая реакция
hypersensivity reactions - реакции на повышенную
чувствительность к препарату
local reactions - локальные реакции