Irritants can be bacteria, friction, chemicals, X-rays, fire, cuts or blows, etc.

Cells infected with viruses and certain other agents produce interferon, the substance that prevents infection of other cells.

Immunity is the power of an individual to resist or overcome the effects of a particular disease or other harmful agents.

There are two kinds of immunity: inborn and acquired. Acquired immunity can be natural or artificial; and also it can be active or passive.

Each person has his own inborn immunity. Acquired immunity is obtained during the life of the person. The immunity response is based on a reaction between antigens and antibodies. Antigens are any foreign substances entering the body.

Lymphocytes react to these foreign substances, they can destroy foreign cells directly, or release substances that stimulate other lymphocytes and macrophages in the destruction of foreign cells (clones of plasma cells). These plasma cells produce specific antibodies that circulate in the blood as gamma globulin fraction.

Each time a person is invaded by the organisms of a disease, his cells may produce antibodies that provide immunity against the infection. Such immunity may last for years and in some cases it lasts for a whole life. It is active immunity. Passive immunity is acquired by a fetus through the placenta and by infants for about six months. Nursing an infant can lengthen this period of protection owing to the presence of specific antibodies in breast milk.

Artificially acquired immunity is created by vaccination or immunization in active or passive ways. Active immunization is immunization with vaccines. Passive immunization is administration of immune serum (antiserum).

Here we can name some disorders of the immune system:

• allergy is hypersensivity to normally harmless substances (allergen);

• autoimmunity is abnormal response to body's own tissues;

- immune deficiency disease is failure in the immune system. It can be hereditary or acquired (AIDS);

- cancer may be partly due to failure of immune system, because it destroys body cells.

Exercise 3. What are the Latin/Greek equivalents of the following English words?

Cells, tissue, allergy, disease, substance, milk, bacterium, antibody, toxin, lymphocyte, macrophage.

Exercise 4. Answer the questions. What do we call:

1. a person who takes care of patients?

2. a doctor who operates on patients?

3. a doctor who treats patients with different medicines and remedies?

4. a person who discovers something new in the field of science?

5. a house where students live?

6. a grown-up person?

7. the organ which pumps the blood through the arteries and veins?

8. a fixed period of time during which students study?

9. the system of the body, which defends the organism from harmful agents?

Exercise 5. Give some examples of inborn immunity, acquired immunity. What is the basic difference between inborn and acquired immunity?

Exercise 6. Answer the following questions.

1. What is the subject of immunology?

2. What is active immunization?

3. What is passive immunization?

4. What takes part in immunity?

5. What is the difference between antigens and antibodies?

6. What does the term "inflammation" mean?

7. What disorders of the immune system do you know?

Exercise 7. Read the information and answer the questions.

• What is the role of vaccines?

• What vaccines are used to prevent infectious diseases?

Immunity can be provided artificially by vaccination and other forms of immunization. A vaccine is a preparation containing the offending organisms - usually in a weakened form that will not cause the actual disease. Currently there are vaccines for polio, measles, rubella, mumps, chicken pox, shingles, and some strains of influenza.

Exercise 8. Translate into English.

1. Алергія - це підвищена чутливість до алергенів.

2. СНІД - це синдром набутого імунного дефіциту.

3. Автоімунітет - це ненормальний вплив самого організму на тканини.

4. Рак може бути причиною порушень імунної системи організму, оскільки вінруйнує клітини організму.

II. Grammar Exercises

Exercise 1. Read and translate the following word combinations. Name the function of participle II in them.

1. The method used in the experiment;

2. the prescribed treatment;

3. the medicines kept in cases A and B;

4. sedatives administered orally;

5. the organism protected from diseases;

6. the given amount of agents;

7. substances called antibodies;

8. drugs used for treatment of cancer;

9) the vaccine given for mumps;

10) the made tests.

Exercise 2. Translate the sentences, state the forms of the verbs.

1. Professor Petrov delivered the lecture in physiology yesterday. 2. Professor Petrov has already delivered the lecture in physiology. 3. Professor Petrov has not yet delivered the lecture in physiology. 4. Yesterday we got interesting findings after our experiments on animals. 5. We have just got some interesting findings after our experiments on animals. 6. We have not yet got any interesting findings after our experiments on animals.

Exercise 3. Find substitutes for the words and word combinations in bold type.

1. Will you take this medicine? Try it. You will feel an immediate relief. 2. When a doctor is listening to the patient's lungs and heart he must put a stethoscope on the patient's chest. 3. Students usually go through the necessary course of treatment at a student's hospital. 4. His pulse turned out to be faster than normal. 5. Oh, I'm glad you have completely recovered. 6. A doctor does his best to stop the process of patient's disease. 7. My friend tried to make me quiet. 8. 1 want very much to go in for sports. 9. This worker got a written permission to be absent from work because of his illness. 10. All my fellow students managed to do this work successfully.

Exercise 4. Make up sentences using the table. Translate them.

He

The doctor I

You They is said are seen was heard were noticed

entering the hospital, crying loudly in the room, walking along the street, operating the patient, speaking with a surgeon.

Exercise 5. Translate the following sentences paying attention to the underlined words.

1. Я часто відсилаю листи додому. 2. Я щойно відіслала цей лист до Англії. 3. Вчора я послала лист своїм батькам. 4. Вчора я відіслала лист своїй подрузі до того, як пішла на лекцію. 5. Які фотографії ти посилаєш зараз у конверті? 6. Я відішлю звіт наступного понеділка.

Exercise 6. Translate into English using the Objective or Subjective Participial Constructions.

1. Його мати хотіла, щоб він став хорошим лікарем. 2. Кажуть, що він вступає до медичного університету. 3. Чути, як медсестра готує інструменти до операції. 4. Він бачив, як я робила ін'єкцію. 5. Бачили, що вони готували пацієнтів до операції. 6. Вона бачила, як він брав книги у бібліотеці.

III. Independent Work: AIDS

Exercise 1. Read the text. Make a vocabulary of new words.

AIDS

AIDS means acquired immune deficiency syndrome. It is caused by the human immunodeficiency virus (HIV). The only identified routes of transmission are through the blood and semen contaminated with the HIV. Transmission can be through sexual contact, exposure to contamined blood and blood products (transfusions, sharing needles used for illegal IV drugs, accidental needle puncture, broken area on the skin directly exposed to contaminated blood), and from pregnant female to unborn child.

When the HIV enters the bloodstream, it attacks the immune system and weakens the person's ability to fight disease. Target cells are T-cells (type of white blood cells called lymphocytes that are produced in the thymus). Although they do not secrete antibodies, T-cells are essential for normal immune function. Without them, cell-mediated immunity deteriorates, allowing opportunistic diseases to invade the body. In response to this invasion, the body begins to produce antibodies. Within two weeks to three months after infection, these antibodies can usually be detected by a blood test.

There are three possible outcomes for individuals who become infected by HIV:

• they can remain healthy, asymptomatic carriers of the virus;

• they can develop AIDS-related complex (ARC);

• they can develop classic AIDS.

Currently, no cure exists for AIDS. All asymptomatic HIV positive persons require periodic T₄ cell tests (also called CD₄ cell count) usually every six months to monitor the status of their immune system. When the CD₄ cell count falls below 500/mm³ (normal is 1000/ mm³), pharmacotherapy is often initiated, followed by laboratory monitoring of the T₄ cells count every three months (AIDS Guide, 1992). Because of the increased risk of opportunistic infections, additional screening tests include:

• skin tests: purified protein derivative (PPD) to rule out tuberculosis (TB);

• Candida, mumps, or tetanus toxoid to evaluate patient's immune response;

• serum studies for hepatitis В antibodies.

Exercise 2. Make a summary to retell the text.

Exercise 3. Answer the following questions.

1. What does AIDS mean?

2. What causes AIDS?

3. What are the ways of transmission?

4. Why is such disease so dangerous?

5. Name three possible outcomes for persons infected with HIV.

6. Can doctors treat AIDS?

UNIT FIFTEEN

I	Speaking	Respiratory System
11	Grammar	Absolute Participial Complex (§105)
III	Independent Work	Lungs