Text A. The physiology of the lungs

Respiration consists of repeated inhalations and exhalations. The respiratory movements are rhythmical. An adult at rest makes 16-20 respiratory movements per minute, children make more movements (a newborn child makes up to 60 movements a minute). Physical exertion is usually accompanied by faster respiration. Accelerated respiration is also observed in many diseases. Sleep is accompanied by a slowing of respiration.

The lungs are the main organs of the respiratory system. The physiology of the lungs is associated with their structure. There are over 700,000,000 alveoli in the lungs. The lungs have many capillaries with the total surface of about 80 sq. m. This particular structure of the lungs enables the exchange of gases between the alveolar air and the blood. Elastic fibers of connective tissue composing the walls of the alveoli, alveolar passages and the visceral pleura enable the lungs to dilate.

When one breathes in the external intercostal muscles contract and lift the ribs. At this moment the diaphragm also contracts and goes down. The volume of the chest increases. The increase of the chest volume enables the lungs to extend. The pressure in the lungs becomes less and the atmospheric air enters the lungs.

When one breathes out the external intercostal muscles and the muscles of the diaphragm become relaxed. The ribs go down, the diaphragm goes up, the volume of the chest decreases and the lungs contract. The pressure in the lungs becomes higher and the air goes out of the lungs.

The vital capacity of the lungs in the male averages 3.5-4 litres and in the female 3-3.5 litres. The regulation of the vital capacity is of particular importance to the exchange of oxygen and carbon dioxide taking place in the lungs.

The respiratory rate and its depth depend on the amount of carbon dioxide in the blood.

TASKS

I. Translate the following word combinations:

ритмичные дыхательные движения; повторные вдохи и выдохи; учащенное дыхание; замедление дыхания; связанный со строением легких; общая поверхность капилляров; дает возможность осуществить обмен газов; соединительная ткань, образующая стенки альвеол; альвеолярные проходы; увеличение объема грудной клетки; мышцы диафрагмы расслабляются; жизненная емкость легких а среднем составляет; частота и глубина дыхания

II. Express your agreement or disagreement with the following statements:

1. Respiration consists of repeated inhalations and exhalations.

2. Children make less respiratory movements than adults.

3. Accelerated respiration is observed on physical exertion and in many diseases.

4. The lungs are the main organs of the cardiovascular system.

5. The physiology of the lungs is associated with their structure.

6. When one breathes in the volume of the chest decreases.

7. The exchange of oxygen and carbon dioxide takes place in the lungs.

8. The vital capacity of the lungs is about 5-6 litres.

III. Read and translate the following sentences:

1. Everybody knows the lungs are the main organs of the respiratory system.

2. The physiology of the lungs we studied at the practical classes is associated with

their structure.

3. The particular structure of the lungs many scientists investigated enables the

exchange of gases between the alveolar air and the blood.

4. We know the volume of the chest decreases when one breathes out.

5. Physiologists found out the total surface of the capillaries in the lungs is about 80

sq. m.

IV. Describe the mechanism:

a. of inhalation

b. of exhalation