What is the function of the bronchial veins

Airways and lungs


The lungs are responsible for breathing and consist of a left and a right lung. Each lung is in turn divided into lobes and traversed by a system of air-conducting paths (the "bronchi"). These end in so-called pulmonary alveoli (the "alveoli"), in which the gas exchange takes place. All of the lower airways, with the exception of the alveoli, are lined with ciliated epithelium, which contributes to the immune defense and cleansing of the lungs. The alveoli, on the other hand, have a very thin epithelial layer so that the breathing gases oxygen and carbon dioxide can diffuse as easily as possible into the surrounding pulmonary capillaries. The pulmonary capillaries are part of the small bloodstream that carries deoxygenated blood from the right ventricle to the lungs and oxygen-rich blood from the pulmonary capillaries to the left atrium. The lungs themselves are supplied by a second vascular system. The blood flow to the lungs is also known as perfusion and is closely related to ventilation - the distribution of breathing gases in the lungs. This is driven by pressure differences between the alveolar space and the outside world, which are generated by the respiratory muscles, among other things. For details on the course of breathing, see also: Breathing mechanics. By the way, you will also find a Histo-Trainer series on the histology of the lungs and trachea in the respective sections on microscopic anatomy.


The windpipe or trachea connects the larynx with the main bronchi of the lungs.

Macroscopic anatomy



The trachea is made up of horseshoe-shaped cartilage braces that are connected dorsally by a plate of muscle and connective tissue.

  • Front: Approx. 20 horseshoe-shaped cartilage clips, connected to one another with ligaments (Ligg.anularia)
  • Back (Paries membranaceus): Consists of connective tissue and muscles (the so-called M. trachealis)
  • Bifurcatio tracheae: Branch of the trachea into a right and a left main bronchus at the level of the 4th BWK

Foreign body aspiration
When liquids or foreign bodies are "swallowed", they enter the tracheobronchial system (instead of the esophagus), which is known as "aspiration". Often children in the 2nd and 3rd year of life are affected, but also patients without appropriate protective reflexes. If the protective reflexes are preserved, attack-like irritable cough occurs, and stridor and dyspnoea can persist. A life-threatening relocation of the trachea leads to severe shortness of breath, cyanosis and asphyxia. Mostly, however, the objects are located in the main and intermediate bronchi after aspiration, more often in the right than in the left bronchus due to the steeper exit. If the urge to cough is ineffective, the Heimlich maneuver can be used to try to mobilize the foreign body.

Vascular supply, innervation and lymph drainage

Topography of the trachea

Microscopic anatomy of the trachea

The microscopic structure of the trachea corresponds to that of the large bronchi (see: Microscopic anatomy of the lungs).

Histo-Trainer for the histology of the trachea and the lungs

Macroscopic anatomy of the lungs


  • Shape: The lungs resemble a rounded cone
  • Size: Volume of 1.5 L on the right and 1.4 L on the left
  • Surface: approx. 100 m2
  • Weight: approx. 800 g
  • Faces and borders
    • Surfaces
      • Facies costalis
      • Facies diaphragmatica
      • Facies mediastinalis
      • Facies interlobaris
    • Margins: Margo anterior and inferior


The lung consists of two lungs, which can be divided into lung lobes, which in turn can be divided into functional segments. A distinction is made between the air-conducting bronchial system and the gas-exchanging alveoli according to their function.

The air-conducting bronchial system

The lobes and segments of the lung correspond to the division of the bronchial system: A lung lobe thus corresponds to the lung section that is supplied with breathing air by a lobe bronchus; a lung segment is defined analogously by the supply area of ​​the segment bronchi.

  • Division of the bronchial system
    • The bronchial tree splits dichotomously about 20 times
    • Depending on the level of division, a distinction is made between:
      • Main bronchi → lobe bronchi → segment bronchi → subsegment bronchi etc.
    • The division of the bronchi also determines the structure of the lung tissue
  • Special features of the left lung (due to the position of the heart)