Exercise 5. Read and translate the text. Anatomy of the respiratory system

ANATOMY OF THE RESPIRATORY SYSTEM

The cells of the human body require a constant stream of oxygen to stay alive. The respiratory system provides oxygen to the body’s cells by removing carbon dioxide.

There are 3 major parts of the respiratory system: the airway, the lungs, and the muscles of respiration.

The airway includes the nose, mouth, pharynx, larynx, trachea, bronchi, and bronchioles.

The nose and nasal cavity form the main external opening for the respiratory system through which air moves. The nasal cavity is a hollow space within the nose and skull that is lined with hairs and mucus membrane which warm, moisturize, and filter air.

The mouth or the oral cavity is the secondary external opening for the respiratory tract. It can be used to supplement or replace the nasal cavity’s functions when needed.

The pharynx, also known as the throat, is a muscular funnel. It extends from the nasal cavity to the larynx and esophagus.

The larynx, also known as the voice box, is a short section between the pharynx and trachea.

The trachea is a tube which extends from the base of the larynx to the lungs, where it divides into two bronchi.

The bronchi are two tubes which begin at the division of the trachea. The left bronchus is slightly longer than the right one as it passes around the heart to reach the left lung. Each bronchus leads into a lung. Inside the lungs, the bronchi divide, and subdivide, into smaller numerous bronchioles. The bronchioles end in very fine alveolar ducts leading to the alveoli.

The alveoli, or air sacs, are the ends of the air passages. Each alveolus is closely surrounded by blood capillaries. There are over 700,000,000 alveoli in the lungs. The total surface of the alveoli is about 90 sq.m (square meters).

The lungs are paired, spongy organs located in the chest. The lungs are divided into lobes - the right lung has three lobes and the smaller left lung has two lobes. Each lung is enclosed in a membranous sac, or pleura. The lungs have many capillaries with the total surface of about 80 sq.m.

It is considered that in the adult the vital capacity of the lungs is about 3-4 liters. When the depth of respiration increases the vital capacity may be 6 litres and even more.

Respiratory diseases range from mild, such as the common cold, to life-threatening like bacterial pneumonia, asthma, pulmonary embolism, and lung cancer.

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