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Bronchial system

German: Bronchialsystem

1 Definition

The term bronchial system covers the lungs and the airways below the trachea.

2 Anatomy

The trachea splits into two at the level of the 4th to 5th thoracic vertebra Main bronchi (Bronchi principales).

2.1 Bronchia

The right main bronchus runs approximately in the direction of the trachea; the left branches off at an angle of about 50-100 degrees. Behind the breastbone lies the heart in the left half of the thorax, the left lung is smaller than the right and has only two so-called lung lobes while the right lung has three.

The left main bronchus divides into two lung lobes and the right into three, whose diameters are 8 to 12 mm in each case. The lobar bronchi divide again - corresponding to the structure of the lung in segments - into segment bronchi which are numbered on both sides, in order to facilitate communication between the doctors. 7 and 8 on the left form a single lung segment with the number 8, thus missing the left bronchus segment 7.

Each bronchus segment splits into two so-called subsegments. Up to a diameter of 1mm, further divisions take place and only thus far contain the bronchial wall cartilage to ensure the patency of the bronchi and thus the ventilation of the entire lung. With further divisions, the glandular cells and ciliated epithelium are formed and under the mucous membrane a ring-shaped muscle syste is formed.

2.2 Bronchioles

With the loss of the cartilage wall the corresponding tubes are now called bronchioles; Goblet cells and epithelium are no longer present. The opening of the lumen is now guaranteed by the elastic fibres. The bronchioles each divide into 4-5 terminal bronchioles and these again into respiratory bronchioles around 1-3.5 mm long and 0.4 mm wide. In places, the alveoli have already formed on the walls. The walls of the alveolar ducts consist of the septa of the alveoli. They end up in alveolar sacs (Saccus alveolaris).

Terminal bronchioles, respiratory bronchioles and alveoli essentially form the basis for the structure of the lung in pulmonary lobules (Lobuli). In the loose connective tissue between these lobules, the interlobular connective tissue, which serves as the necessary deformability of the lungs, fluid can easily accumulate and then interstitial oedema occurs. Even air can penetrate here thus leading to interstitial emphysema.

3 Clinic

Inflammation of the bronchial mucosa is called bronchitis.

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