Complete information on the mechanism of Respiratory System in Man NIRMALA AGARWAL
Respiratory organs are those which are concerned with the passage of the air to and from the lungs. The latter are, of course, mot important of all. The passage is also called respiratory tract. For the sake of convenience, the respiratory tract can be divided into upper and lower parts. The upper part extends from the external nostrils (external openings of nose) to the vocal sac present in the neck. The lower part extends from the vocal sac to the lungs. The nose has a passage called nasal passage which is lined by ciliated epithelium rich in blood capillaries. This passage is hairy. When the air passes through the nose, certain amount of dust of the air is trapped and the air is warmed up. Behind the nasal passage is the vocal sac or the larynx. It is called Adam’s apple. Behind the larynx is a wind pipe called the trachea. It is a 12-cm long tube whose diameter is about 16mm. it is surrounded by incomplete rings of cartilages. As the air passes down the trachea, it becomes humidified, because some moisture from the mucus gets mixed up in it. The trachea divides at the lowe4r end into two bronchi. Each bronchus divides in turn to form thinner tubes called bronchioles. The respiratory tract from the nose to the bronchioles is lined by ciliated epithelium. Bronchioles enter the lung and divide further into finer branches, the alveolar ducts, which open into the air sacs (alveoli). Mechanism of Respiration in Man
Here, we are not going to discuss the biochemical mechanism of respiration. We shall discuss only the process of renewal of atmospheric air in the lung. In other words, we will discuss how we take the air into our lungs and how we expel it. The lungs occupy most of the chest cavity. This cavity is lined with a serous membrane, the pleura. There is a small amount of serous fluid between the lungs and the pleura. This fluid lessens the friction between the membrane and the...
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