Text B. BLOOD

Blood is a fluid tissue with many various functions. Not only important physiological process takes place in the blood but it determines the activity of body cells. Blood is composed of plasma and the corpuscular elements which are called red corpuscles or erythrocytes, white corpuscles or leucocytes and blood platelets or thrombocytes.

About 65 per cent of all white cells are leucocytes. The function of leucocytes primarily that of protection against infection. Their life span is short from 4 to 12 days. It is generally considered that no sex differences exist in the count of leucocytes. The count of leucocytes in the blood of a healthy person is 4,500 to 9,500 per cu mm (cubic millimeter). If the number of white blood cells (WBC) is counted after mental or physical exertion or meals it may increase to 10,000 or more per cu mm. The cells that comprise about 35 per cent of the white cells are lymphocytes. They are produced in lymph nodes.

It is estimated that the erythrocytes are the most numerous cellular elements ranging from 4,000,000 to 5,000,000 per cu mm. The red blood cell count (RBC) may change with age. When the red blood cell count is done after physical exertion or emotions it may increase.

One knows that red corpuscles have two physical features which are very important in the function of respiration. They have great elasticity and flexibility. These features give them the possibility to pass through very small capillaries.

The most important part of the red cell is its red colouring substance or hemoglobin which on an average forms about 36 % of its mass.

The total blood volume is divided into circulating and reservoir ones.

The average human blood volume is not less than 7.5 % but not more than 10% of the body weight. It is generally stated that the circulating volume averages smaller in the females than in the males. The circulating volume of the blood depends on the changes of the air temperature.

TASKS

I. Complete the sentences:

1. Blood is a …. 2. Blood is composed of …. 3. About 65% of all blood cells are … 4. The cells that comprise about 35% of the white cells are …. 5. Blood platelets are …. 6. The most numerous cellular elements are …. 7. The red corpuscles have two physical features …. 8. The most important part of the red cells is …. 9. The … is about 7.5 to 10% of the body weight.

II. Combine the adjective in A with the noun in B:

A B

fluid volume

blood temperature

corpuscular elements

healthy tissue

mental surface

physical features

maximal exertion

air person

III. Use the proper prepositions:

1. Important physiological process takes place … the blood.

2. Blood is composed … plasma and corpuscular elements.

3. If the number of white blood cells is counted … mental or physical exertion it may

increase.

4. The number of red blood cells ranges … 4,000,000 … 5,000,000 per cu mm.

5. The red blood cell count may change … age.

6. Elasticity and flexibility give erythrocytes the possibility to pass … very small

capillaries.

7. The circulating volume of the blood depends … the changes of the air temperature.

IV. Translate the sentences:

1. Известно, что кровь это жидкая ткань.

2. Установлено, что 65% белых клеток – лейкоциты, а 35% - лимфоциты.

3. Считают, что половых различий в количестве лейкоцитов не существует.

4. Доказано, что эритроциты имеют две физические особенности.

5. Известно, что общий объем крови составляет 7.5-10% общего веса крови.

6. Установлено, что гемоглобин образует примерно 36% массы эритроцитов.

V. What do you know in general:

about leucocytes

about erythrocytes

about blood