The lung in gas exchange organ, is located within the mediastinum on both sides of the chest, around each one. Pulmonary top circle is called a blunt apex, upward through the thoracic outlet broke into the root of the neck, bottom is located above the diaphragm on the rib and intercostal space to the surface called the rib side of the mediastinum toward the side of the plane called the inside of the surface the central bronchi, blood vessels, lymphatic vessels and nerves out of Office, called the hilum, the access to hilar structures, were wrapped with connective tissue called the pulmonary root. Left lung from the oblique fissure is divided into upper and lower two lobe, right lung except oblique fissure, there is a split-level will be divided into upper, middle and lower three lobes.
Bronchial lung is formed by repeated branching bronchial tree-based composition. The left and right bronchus is divided into the second level in the hilar bronchus, secondary bronchi and its branches under the jurisdiction of reference form a lobe, each second-level separation of third stage of bronchial bronchial Also, each third-grade bronchial and branch of the scope of jurisdiction constitutes a lung segment bronchus in the lungs repeatedly branch-level up to 23-25 and finally the formation of alveoli. Bronchial branches at all levels, among and between the alveolar connective tissue stroma by filled, blood vessels, lymphatic vessels and nerve branches distributed with the bronchial connective tissue. Alveolar interstitial between the rich capillary network, together constitute the alveolar capillary membrane and respiratory membrane, blood and alveolar gas exchange gases must be carried out through the respiratory membrane, respiratory membrane area is larger, an average of about 70 square meters , quiet state, of which only 40 square meters used for the breathing gas exchange, so in due to illness and other reasons leading to respiratory membrane area of less than 40 square meters before the lung ventilation does not appear significant obstacles. Cover the surface of a layer of pulmonary smooth serosa, that visceral pleura.
Bronchial lung is formed by repeated branching bronchial tree-based composition. The left and right bronchus is divided into the second level in the hilar bronchus, secondary bronchi and its branches under the jurisdiction of reference form a lobe, each second-level separation of third stage of bronchial bronchial Also, each third-grade bronchial and branch of the scope of jurisdiction constitutes a lung segment bronchus in the lungs repeatedly branch-level up to 23-25 and finally the formation of alveoli. Bronchial branches at all levels, among and between the alveolar connective tissue stroma by filled, blood vessels, lymphatic vessels and nerve branches distributed with the bronchial connective tissue. Alveolar interstitial between the rich capillary network, together constitute the alveolar capillary membrane and respiratory membrane, blood and alveolar gas exchange gases must be carried out through the respiratory membrane, respiratory membrane area is larger, an average of about 70 square meters , quiet state, of which only 40 square meters used for the breathing gas exchange, so in due to illness and other reasons leading to respiratory membrane area of less than 40 square meters before the lung ventilation does not appear significant obstacles. Cover the surface of a layer of pulmonary smooth serosa, that visceral pleura.