Respiratory system of man
Respiration is the process by which the body's cells supplied with oxygen, it stimulates metabolic reactions necessary for absorption of nutrients. Cells turn oxygen into carbon dioxide (carbon dioxide) and return it to the blood to be eliminated from the body. Such gas exchange (oxygen is inhaled, carbon dioxide exhaled) is a basic, vital function of the respiratory system, furthermore, certain parts perform the function of the senses.
The respiratory system consists of nose, pharynx, trachea, bronchi, and lungs.
The nose is a structure of bone and cartilage covered with muscle tissue and skin. Lined with mucous membrane the inner surface of the nose is connected with the nasopharynx by two channels of the nostrils. Inhale through the nose the air is warmed, moistened and filtered, passing through three basins — the outputs of the bone covered with a mucous membrane which consists of cells capable of trapping dust and microbes.
Next, the filtered air enters the nasopharynx, located behind the internal nasal cavity. From the nasopharynx the air and mucus coming down throat, in addition, it is connected Evstafieva pipes with an inner ear that allows you to equalize the pressure on both sides of the ear to the eardrum. The throat has the shape of a "chimney" and performs three functions: it held air and food, in addition, it located the vocal cords. In the mouth, the middle part of the pharynx receives mouth full of food, drink and air, it also has almond-shaped glands (tonsils).
The lower part of the pharynx, hypopharynx, also pass through air, liquid and food. From the larynx it is two vocal cords. The flow of air entering into the gap between them, creates a vibration, so we hear ourselves and others. The epiglottis is elastic cartilage located at the base of the tongue and connected "trunk" with the Adam's Apple. The process of this cartilage can move freely up and down. When swallowing, the larynx rises, causing the cartilage "tongue" of the epiglottis to descend, covering its original cover. With this food enters the esophagus and not the Airways. The larynx continues to the trachea, or else — the windpipe, with a length of about 10 cm the wall of the trachea are supported by incomplete cartilaginous rings, making it hard and at the same time flexible; when located near the esophagus passes food, trachea is served slightly caving in.
The inner surface of the trachea is also covered with a mucosal lining that traps dust particles and microorganisms, which are then written up and out. The trachea divides into left and right pleural bronchi structurally similar to the trachea that lead respectively into the left and right lung. Bronchi branch out into smaller channels, those into even smaller and so on until the pneumatic tube do not develop in the bronchioles.
The lungs have the shape of a cone stretching from the collarbone to the diaphragm. The surface of each lung is rounded, which allows them to closely fit the edges, and represents the pleural membrane, one surface of which is in contact with the walls of the chest cavity, and the second is addressed directly to the lungs. The pleural cavity located behind the membrane produces a lubricating fluid that prevents friction between the two membranes. Axis of the lung area, called gates, here in the lung consists of nerves, blood and lymphatic vessels and the primary bronchi. Each lung is divided into lobes: two on the left and the right into three, which are divided into smaller segments (each lung of ten). Each pulmonary lobe are arteriole, venules, lymphatic vessel and a branch of the bronchioles. Then the bronchioles branch into respiratory bronchioles, and they — alveolar passages, which, in turn, are divided into alveolar sacs and alveoli. In the alveoli gas exchange occurs. As you move the respiratory channels in the light in their structure reduces the number of muscles and cartilage, which are replaced by delicate connective tissue.