Сократите текст для пересказа: 1. Respiration occurs in all living things, both plants and animals.The рroper function of this system is perhaps the most important one in the sustaining of life. Interruption of breathing for only a few minutes by suffocation or strangulation causes death. In the human organism, respiration consists of those processes by which the body cells and tissues make use of oxygen and by which carbon dioxide or the waste products of respiration are removed.

2. Inhaled air contains about 20 per cent oxygen and four hundredths of one per cent carbon dioxide. Exhaled air consists of approximately 16 per cent oxygen and 4 per cent carbon dioxide. Nitrogen, which makes up about 79 per cent of the atmosphere, is not involved in the breathing process. When air is inhaled into the lungs, a portion of the oxygen is passing into the blood and is being circulated through the body. At the same time, carbon dioxide is being diffused out of the blood into the lungs and exhaled.

3. Air is breathed through either the mouth or nose into the oral cavity, or pharynx. It then passes through the voice box, or larynx, into the windpipe, or trachea. The trachea ultimately divides into two smaller tubes, bronchi, one is going to each lung. The bronchi divide into tiny passage-ways that are named bronchioles, which lead directly to minute air sacs, or alveoli. The exchange of life-giving gases is effected through the walls of the alveoli.

5. Other structures which are connected with the system include: the laryngeal tonsils, which are masses of tissue in the nasopharynx or posterior portions of the nasal passages (adenoids are infected or diseased laryngeal tonsils); the sinuses, cavities in the bones in the front part of the skull that provide resonance to the voice, and the pleura, a doublewalled membrane which surrounds the lungs.

6. When the diaphragm contracts and flattens, it contributes to the extension of the vertical diameter of the thoracic cavity. Air is constantly renewing in the lungs. The capacity of the air passages is increasing. Any muscular effort, e.g. even standing up, increases the number of respirations.

danil1365334    1   09.01.2021 17:43    149