Respiratory tract

As respiratory tract or respiratory apparatus ( Apparatus respiratorius ) the entire system responsible for the respiratory system is called. The air-conducting organs or respiratory be distinguished from the gas exchange serving lungs.

For respiratory system include

• Nose
• Throat
• Larynx
• Trachea
• Left and right main bronchus or Luftröhrenhauptast ( bronchus principalis )
• Bronchia
• Bronchioles
• Alveoli (alveoli )

The bronchial takes a special position in so far as it constitutes Although geographically the largest part of the air-conducting paths, however - is embedded as " bronchial tree " in the lungs - with the exception of the main bronchi. The conductive in the alveolar hollow organs have three tasks, namely to filter particles as precipitation, to warm and moisten the air you breathe.

The volume of air which is located in the airways is also referred to as dead space within the total volume of inhalation and exhalation, as it only participates through the air movements ( mixing, swirling ) and the gas exchange in the alveoli.

Embryology

The system of the lungs is formed when people already at the three week old embryo as an evagination of the foregut and thus comes from the inner germ layer ( endoderm ). In the 5th week of pregnancy, this sac ( " Lungendivertikel " ) is separated from the foregut ( oesophagotracheale septum) completely through a septum, an open connection is maintained only in the region of the later larynx. Simultaneously with the pinching off from the foregut, which develops in its posterior part of the esophagus, the plant grows out of the respiratory tract to the rear. The central portion is to the trachea, which then divides into the two lung buds at the end.

The lung buds divided right into three branches, two in the left - the investments of later lobar bronchi, which divide dichotomously in consequence on. About 17 such divisions take place until the end of the sixth month of pregnancy, the other 6 divisions take place until after the birth. The mesoderm surrounding the bronchial tree develops into cartilage, smooth muscle and blood vessels.

The into the body cavity ( coelom ) outgrowing pulmonary systems push the mesoderm layer covering it in front of him. From this layer as a result the " pleura ", the visceral pleura develops.

The alveoli are formed at the terminal branches of the pulmonary system in the 7th month of pregnancy, with the cells of the alveolar epithelium invest directly in the epithelium of the adjacent capillaries to ensure the later problem- gas exchange. In addition to the Alveolarenzellen form so-called niche cells, the surfactant, a surfactant, produce and thus prevent after birth, the collapse of the alveoli. A lack of production of surfactant leads without treatment in preterm infants for so-called syndrome of hyaline membranes.

Up until birth, the alveoli are filled with amniotic fluid. During childbirth, this partially pressed out of the alveoli, the rest is absorbed in the following hours, so no later than the 3rd day of life all alveoli are ventilated.