Article overview bronchi
- What are the bronchi?
- What is the function of the bronchi?
- Where are the bronchi?
- What problems can the bronchi cause?
What are the bronchi?
The bronchi form a richly branched tube system in the lungs - a guidance system for the breathing air: The two main bronchi emerge from the division of the trachea and lead into one of the two lungs. There are still numerous other branches, the bronchi becoming smaller and thinner: First, each main bronchus divides into three (right lung) and two (left lung) lobe bronchi - corresponding to the three or two lung lobes. That the left lung has a lobe less than the right is because the heart needs space.
The lobar bronchi branch further into the segment bronchi, which also continue to ramify. The smallest bronchi, whose diameter is less than a millimeter, are called bronchioles. They lead to the tiny, delicate alveoli, in which the gas exchange takes place.
As the branching of the bronchi increases, their wall structure changes. At first, the walls are reinforced by cartilage clips to keep them stable. The free ends of these cartilage braces are strained by strands of smooth muscle that is controlled by the nervous system. In the course of branching, the proportion of cartilage in the walls decreases, while the proportion of smooth muscle increases. Finally, the bronchioles only have one muscle wall without cartilage.Acute bronchitis - what you can do yourselfWhat can you do about the painful cough? And how can you prevent it? What can you do about the painful cough? And how can we prevent it?
What is the function of the bronchi?
The bronchi conduct the respiratory air from the upper respiratory tract (nose, mouth, pharynx, larynx) and trachea to the approximately 300 million alveoli at the end of the bronchioles. These are surrounded by a network of tiny blood vessels (capillaries) and the place for the gas exchange: Through the gossamer walls of the alveoli, oxygen from the respiratory air is released into the blood and carbon dioxide is absorbed from the blood into the respiratory air, which is then exhaled.
The interior of the bronchi (like that of the trachea and the upper respiratory tract) is lined by a respiratory epithelium. It contains, among other things, cells that produce mucus, where small and very small particles that have entered with the breathing air are stuck. Adjacent ciliated epithelial cells then carry these particles with their cilia to the outside, where they can be coughed off.
In physically active phases, for example during sports or during hard physical work, the activation of the sympathetic nervous system relaxes the muscles around the bronchi. These have a larger diameter and it can flow through more air and reach the alveoli: The blood is supplied with more oxygen. During periods of physical rest, the bronchi narrow because the parasympathetic nervous system is then activated.