Blood: Its Composition and Functions

 

Our blood has two basic parts: blood cells, which are also called blood corpuscles, and plasma, the fluid in which the blood cells are suspended.

Most of the blood cells are red blood cells, or erythrocytes. Their dimensions are very small: if these cells, invisible to the naked eye, were collected from the entire body and placed one-thick on a flat surface they would occupy an area of 1000 sq.m. The red colour of erythrocytes is due to the hemoglobin they contain, which combines with oxygen in the lungs and releases it to the tissues as the blood circulates through the body. The red cells also carry the waste product carbon dioxide from the tissues to the lungs so that it can be exhaled. The life span of one red blood cell is about three and a half or four months. New erythrocytes are formed in the red bone marrow, from whence they emerge into the blood to take up their work.

Our body also contains white blood cells, or leucocytes, which protect the body from infection. There are several different kinds of white blood cells. Most of them are neutrophils, which attack and engulf bacteria. Another kind, the lymphocyte, recognizes foreign cells, infectious agents, and participates in the body’s immune reaction against them.

A third type of blood cell is the platelet, also called thrombocyte. Platelets plug the hole in an injured blood vessel. They take part in the blood clotting process.

Most blood cells are produced in the bone narrow. However, lymphocytes are made in the spleen or in the lymph glands, which are found in the neck, armpits, groin and many other parts of the body. The spleen and lymph glands, together with the channels and ducts connecting them, are called the lymphatic system. When red blood cells and platelets become old or defective they are filtered out of the bloodstream and broken down by the spleen, and also by the liver and lymph glands.

 

Anemia

Disorders of the blood are grouped as follows: lack of hemoglobin, which causes anemia; disorders in clotting, which cause bleeding and bruising (hemophilia); cancerous changes in the white cells, which cause leukemia; disorders in the production of blood cells in the bone marrow; and disorders that affect the lymphatic system.

Anemia is defined as a decrease in either hemoglobin or the number of red blood cells to below the normal level. Iron is an essential ingredient in hemoglobin. If there is not enough iron in the body, there cannot be made enough hemoglobin. This form of anemia is called iron-deficiency anemia. There are some types of anemia caused by deficiency: iron, B12 and folic acid deficiency anemia. A severe shortage of vitamin B12 in the body also affects the production of red blood cells. This is called B12 deficiency anemia. Lack of folic acid in the body has the same effect, and this is called folic acid deficiency. There is also  hemolytic anemia when the red blood cells are destroyed more quickly than they normally would be and the number of red blood cells in the body may fall well below normal. Inherited defects of the blood such as sickle-cell anemia cause the body to produce abnormal hemoglobin.

All these types of anemia may be found in children but the most common one is iron-deficiency anemia. Insufficient iron in the body causes an adequate production of hemoglobin, and therefore leads to iron-deficiency anemia.

Normally, extra iron is stored in the body and then used to produce hemoglobin in newly developed red blood cells. Most of this iron is recovered as old red blood cells are destroyed. The small amount of iron lost from the body is replaced by iron absorbed from the diet. If the person loses more iron than he is able to absorb he may become anemic. There are three general causes for a lack of iron reserves: there may not be enough iron in the diet; the digestive system may be unable to absorb iron, even though there may be enough of it in the diet; and an excessive loss of blood.

The most frequently observed type of anemia among very young children is anemia caused by faulty nutrition. Such anemia is rarely seen in breast-fed infants. If an infant receives a monotonous milk or cereal dietary and has not enough vitamins he will develop anemia; therefore bottle-fed babies chiefly suffer from anemia.

Anemia associated with some disease is not uncommon in young children Such anemias are either a result of the direct action of the bacterial toxin on the bone marrow, or are caused by the monotonous and restricted diet employed for the treatment of the basic disease.

The most typical form of anemias among children of preschool ages are those caused by a worm diseases or by faulty hygiene.

The disease in older children would not have developed provided they had not neglected fresh air and sun, physical training and sports.

The characteristic symptoms of anemia include paleness, fatigue, weakness, fainting, breathlessness and palpitations. And no doctor will ever risk diagnosing or treating anemia unless he first does blood test.Nowadays tests:

• check the size and shape of the red blood cells with a microscope check the amount of hemoglobinand iron in the blood
• check how fast new RBCs are being made
• To make a complete differential diagnosis a doctor should check for any inherited anemias and check other cells made in the bone marrow (such as white blood cells).

Anemia is treated by means of numerous excellent drugs the pharmaceutic industry provides us with. However, one form of treatment is irreplaceable in all types ofsevere blood loss: this is blood transfusion.

Anemia, as any other disease, is easier to prevent than to cure. A most important condition for preventing anemia is proper management of nutrition from the very first days of the baby’s life. The best food for infants is breast milk. As the child grows older his food must become varied. No less important are proper hygiene, hardening procedures and fresh air.

 

 

 

Words to remember:

 

Pale(ness), skin, invisible, entire, surface, life span, to carry, to develop, faulty, to neglect, to harden, to explain, numerous, to prevent, to cure, therefore.

 

 

EXERCISES

 

I. Answer the following questions:

 

1.What is blood? 2. What does blood consist of? 3. What is anemia? 4. In what way are the red blood cells related to anemia? 5. How is anemia diagnosed? 6. What are the most frequently observed types of anemia in very young children? 7. What types of anemia are typical for preschool ages? 8. What does the treatment of anemia depend on? 9. What measures usually prevent anemia?

 

II. Complete the following sentences choosing the right ending  from below:

 

1. Anemia may be caused by…

a) specific microorganism; b) contact with infected persons; c) faulty nutrition and faulty hygiene; d) ingestion of contaminated food;

 

1. The most important method for early diagnosis of anemia is …

a) clinical history; b) X-ray examination; c) physical examination: d) blood test;

 

3. Treatment of anemia requires …

 

a) surgical intervention; b) special pharmaceutic medicine; c) physiotherapy; d) bed regimen and good nursing;                                     

 

III. Write down the summary of the text.

 

 

                        BLOOD TRANSFUSION

 

The transfer of blood from a donor to a recipient is one of the most widely used procedures in medical treatment. When severe hemorrhage has resulted in a great loss of blood, a transfusion will restore the circulating blood volume and the red blood cells which provide oxygen and food to the body tissue.

Blood transfusion is invaluable supporting treatment for surgical shock, to replace an excessive loss of blood at childbirth or in such condition as leukemia.

In some cases, even when the circulating blood volume is normal, transfusion is used to replace a deficiency in one of the constituents of the blood, thus providing red cells in cases of acute anemia or in hemophilia which is due to the lack of a specific clot-promoting factor in the blood plasma.

The first recorded transfusion is believed to have been performed between two dogs in 1665. However, the results in human beings were disastrous.

The existence of human blood types was established only in 1902 when the scientists began a study to determine why fatalities occurred following some blood transfusions. It was discovered that the cause was in an incompatibility between the blood of the donor and that of the recipient. Progress was made in this field. For many years only direct transfusions were made, because no means of keeping fresh blood from clotting were known.

  However in 1914 it was found that sodium citrate served this purpose and by this discovery an incalculable number of lives were saved during the First World War.

   Since that time methods have been perfected for obtaining and storing human blood for future use. Blood banks for emergency use have become a part of many hospitals. All blood which is to be used for transfusions is obtained under the most exacting sanitary conditions completely free from germs or other contaminating influences.

    As a safety measure, before a patient receives a whole blood transfusion, the compatibility of his blood with the donor blood is checked by a cross-match test.

     Small samples of red blood cells and sera of the two bloods are combined and examined under a microscope for signs of incompatibility or clumping.

 

 Notes:

1. hemophilia – болезнь крови, характеризующаяся кровоточивостью
2. sodium citrate –лимоннокислыйнатрий – цитратнатрия
3. cross-matchtest –проба на перекрестную совместимость
4. clumping –склеивание, агглютинация

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Active Words to remember:

To transfer, transfusion, to result in, to restore, to lose (lost, lost); loss, food, to replace, deficiency, clot-promoting factor; field, to serve, purpose, a cross-match test.

EXERCISES

 

 

I. Find the word differing in its meaning from the given series of words:

 

1. a) many; b) a great deal of; c) a lot of; d) a number of; e) a few.
2. a) large; b) extensive; c) considerable; d) adequate; e) colossal.
3. a) similar; b) alike; c) artificial; d) the same; e) analogous.
4. a) to provide; b) to supply; c) to change; d) to equip; e) to furnish.
5. a) to result in; b) to bring to; c) to lead to; d) to carry out; e) to end.
6. a) to perform; b) to appear; c) to carry out; d) to fulfill; e) to make.
7. a) to think; b) to suppose; c) to believe; d) to receive; e) to consider.
8. a) to report; b) to announce; c) to defend; d) to inform; e) to tell.
9. a) recent; b) ancient; c) modern; d) new; e) fresh.
10. a) to record; b) to receive; c) to write down; d) to note; e) to register.

 

II. Fill in the blanks with one of the four words given under the sentence:

 

1. Human bloods are divided into four groups, the serum of one group … and haemolyse the corpuscles of another group.

a) may become b) may agglutinate c) may associate d) may complete

 

1. The group test is used to select donors of particular group … to match a particular recipient … to stock a blood bank.

a) either … or b) neither … nor c) not only … but also d) apart from

 

1. The donor should be in a good health and … malaria, syphilis or other

communicable diseases.

a) due to b) result from c) free from d) apart from

 

1. In withdrawing the blood full antiseptic precautions must be used and … to the air must be reduced to the minimum.

a) future b) temperature c) pressure d) exposure

 

1. Before … blood should be preferably warmed to body temperature.

a) transfusion b) distension c) eruption d) resolution

 

1. The method of administration of plasma is … as for whole blood.

a) some b) sometimes c) the same d) several

 

III. Find the corresponding Russian equivalent to the following English words

and word combinations:

 

1. widelyusedprocedure            1. количество циркулируемой крови

2. condition                                 2. группы крови у человека

3. the transfer of blood                3. несовместимость

4. clot-promoting factor              4. заболевание

5. thecirculatingbloodvolume  5.широко распространенная процедура

6. humanbloodtypes                  6. способы хранения свежей крови

7. incalculablenumber7. переливание крови

8. cross-matchtest                      8.фактор, способствующий образованию сгустка

9. incompatibility                        9. проба на перекрестную совместимость

10. means of keeping fresh blood 10. несметноеколичество

 

IV. Translate into Russian. Pay attention to the pronouns any, no, it.

 

1. Like any other symptom a cough is a manifestation of a disease or abnormality. 2. An abscess may form in any part of the body when staphylococcic or streptococcic bacteria invade an area and produce a local infection. 3. The hands should be washed before eating, especially after prolonged soiling or contact with anything in which dangerous bacteria are likely to live. 4. No period of life is immune to the flue. 5. Vitamin B12 is the only vitamin which contains a metal in its very complicated molecule. It seems to be synthetized only by microorganism, yet in our diet it exists virtually exclusively in foods of animal origin. 6. Any disease may become dangerous to life if you do not treat it from the very onset. 7. It was decided to explore the abdomen as there were some signs suggesting peritonitis. 8. It is through the nervous system that the organism is able to orientate itself in the world surrounding it and to adapt itself to the ever changing conditions of life. 9. In perfectly normal states the eruption of teeth is unattended by any symptoms whatever. 10. While inspecting the child nothing can be determined if the child is at all excited. 11. To anyone who has taken an interest in the surgery of early life, it must have become apparent that the child is subject to almost all the diseases of adult life and to many other conditions not found in the adult. 12. Any infant,particularly prematurely born one, requires special care and attention. 13. X-ray of the chest and upper gastrointestinal tract showed no abnormality. 14. No changes in the infant’s general appearance, weight, appetite, behaviour should escape the mother’s notice.

 

V. Find the word nearest in meaning to the one in bold type

 

1. Lack of vitamins in food may lead to metabolic changes and retardation of the development in a growing organism.

 

a) efficiency b) deficiency c) inhibition d) elevation

 

2. In childhood there are various conditions which may produce cough, cold in the head and other catarrhal symptoms

 

a) different b) extreme c) excessive d) common

 

3. Nowadays many childhood diseases end in complete recovery.

 

a) perish b) delay c) terminate d) convert

 

4. The muscles contain nearly one half of the body water.

 

a) hardly b) only c) about d) above

 

 

5. A number of diseases of respiratory system are attended by cough of various types.

 

             a) aggravated b) associated c) accompanied d) affected

 

6. The child’s pulse becomes more rapid during fever, following exercise, anemia or other causes.

 

a) throughout b) before c) after d) without

 

7. There are many methods and procedures employed  to disclose a disease or a defect in a human organism.

 

a) to check b) to aggravate c) to prove d) to reveal

 

VI. Find the word differing in its meaning from the given series of words.

 

1. a) infectious b) contagious c) contaminating d) catching e) promoting f) communicable.

2. a) to require b) to replace c) to call for d) to want e) to need f) to demand.

 

3. a) to decrease b) to reduce c) to result in d) to subside e) to diminish f) to abate.

 

4. a) important b) valuable c) significant d) vital e) loose f) considerable.

 

5. a) to assist b) to support c) to help d) to offer e) to aid f) to back.

 

6. a) regularly b) systematically c) punctually d) largely e) uniformly f) steadily.

 

7. a) to consult b) to answer c) to question d) to ask e) to interrogate f) to inquire.

 

 

VII. Give talks on the subject.Suggested topics are:

 

1. Describe the work of blood transfusion station

2. Describe the history of blood transfusion

3. Describe the administration of blood transfusion in medical practice.

4. Describe the conditions under which blood for transfusion is obtained and stored.