How does a medicine or drug act on the body?

 

There are many different diseases and medical conditions and thousands of medicines and drugs have been produced to help people who need treatment. Each has its own way of working and we each react differently so the process is very complex and difficult to understand. Here are some examples of ways in which medicines and drugs work:

Aspirin

Enzymes are large protein molecules which control the chemical reactions in our bodies. When cells are injured, an enzyme makes substances called prostaglandins which aggravate inflammation, fever and pain. Aspirin works by blocking the action of the enzyme which makes the prostaglandin and at the same time relieving the pain and inflammation in other ways.

Antibiotics

As a part of the body's defence against disease it produces antibodies to invading bacteria, but if these are not able to combat the disease, medicines may have to be taken as well. Penicillin and other antibiotics kill invading bacteria by weakening the bacterial cell wall and causing the bacteria to swell and burst. Human cell membranes have a different chemical structure from the bacteria and are not damaged by these drugs.

Penicillin also helps to reduce the bacterial cell division, and this slowly helps defeat the invading bacteria.

The correct dosage of the antibiotic must be taken and the whole course of treatment followed. This is because problems can arise if antibiotics are not used according to doctor's instructions. The bacteria can become resistant and so the drug gradually becomes less effective.

Drugs for incurable diseases

Some medicines and drugs are used to treat chronic conditions which have no cure, such as diseases of the central nervous system. By controlling or reducing the symptoms of the disease, medicines and drugs can improve the sufferer's quality of life. For example, Parkinson's disease affects over 100,000 people in Britain, most of them elderly. It causes muscle stiffness and severe shaking. The drug Levodopa reaches the brain through the blood system and helps to improve balance and reduce the shaking. Sometimes drugs which act on the central nervous system have unwanted side effects on the person's personality and emotional state. Some people feel depressed and 'not themselves'. However, these side effects can usually be controlled by using other drugs and for most people relief from the symptoms of the disease is the most important effect.

 

Комментарии к тесту

- защита организма от заболевания - сокращать - становиться стойким - контролировать при помощи чего-то - ухудшать, усиливать

body’s defenses against disease

to reduce

to become resistant

to control by something

to aggravate

 

 

13. Прочтите и переведите текст, используя словарь. Скажите на английском языке,

какие типы нейрофармакологических препаратов описаны в тексте.

Neuropharmacologic drugs

 

These drugs act on the nervous system. There are two major types of neuropharmacologic drugs: autonomic drugs and central nervous system drugs.

Autonomic Drugs. These drugs influence the body in a manner similar to the action of the parasympathetic and sympathetic nerves of the autonomic nervous system.

The function of the sympathetic nerve network in the body is (1) to stimulate the flow of epinephrine from the adrenal gland, (2) to increase heart rate, (3) to constrict blood vessels, and (4) to dilate air passages.

Drugs which mimic the action of sympathetic nerves are called sympathomimetic or adrenergic agents. They stimulate the flow of epinephrine, increase heart rate, constrict blood vessels, and dilate air passages. Examples of sympathomimetic drugs are epinephrine (adrenaline) and norepinephrine (noradrenaline). These drugs are the same chemicals which are naturally released from the sympathetic nerve endings and adrenal glands during times of stress emergency.

Drugs which mimic the action of parasympathetic nerves are called parasympathomimetic or cholinergic agents. These drugs oppose the actions of the sympathomimetic (adrenergic) drugs, which means that they slow down heart rate, constrict air passage, and stimulate involuntary muscles in the digestive tract and other organs. The parasympathetic agent which is produced normally at all times by parasympathetic nerve endings is called acetylcholine. Acetylcholine, unlike a drug such as epinephrine (adrenaline), cannot be administered to a patient. This is because there are enzymes in the body called cholinesterases which inactivate acetylcholine almost as quickly as it is given. Other cholinergic drugs are, therefore, chosen as exogenous agents. One example of a cholinergic drug similar to acetylcholine in effect but longer lasting in the body is bethanechol. Bethanechol (Urecholine) is used in postoperative urinary retention to include the constriction of the urinary bladder, aiding urination.

Other autonomic drugs are parasympatholytic agents which oppose the effect of parasympathetic nerve stimulation. Examples of these drugs are atropine and belladonna, which are also known as antispasmodic drugs because they act to relax the muscles in the gastrointestinal tract and decrease peristalsis.

Sympatholytic agents, which block the action of the sympathetic nervous system, include reserpine, guanethidine, and phentolamine. These drugs are used to decrease blood pressure and protect against the excess of epinephrine secretion liberated by pheochromocytomas (tumors of the adrenal gland).

 

14. Прочтите и переведите текст, используя словарь. Скажите на английском языке, какое действие оказывают антигистаминные средства на организм человека.

Antihistamines

 

These are drugs which block the action of chemical called histamine which is found in the body. Histamine is produced by most cells and especially by sensitive cells under the skin and the respiratory system. When certain foreign antigens (protein substances which lead to the production of antibodies) enter the body, antibodies are made by cells. These antibodies attempt to inactivate, or neutralize, the offending antigens and, as a result, a chemical called histamine may be released by other cells. Histamine causes the characteristic allergic symptoms when it is liberated from cells: itching, hives, allergic rhinitis, bronchial asthma, high fever, and, in some very serious cases, anaphylactic shock.

Antihistamines, by blocking the action of histamine in the body, can relieve the allergic symptoms which histamine produces. Antihistamines cannot cure the allergic reaction, but they can relieve its symptoms. Some potentially dangerous side effects of antihistamines are drowsiness, sedation, and blurred vision. Examples of antihistamines are diphenhydramine (Benadryl), meclizine (Bonamine), chlorpheniramine (Chlor-Trime-ton) and tripelennamine (Pyribenzamine).