The alveolocapillary tissue layer has a total area of 75 meter sq . in an adult. Air flow is taken in through the air passages including the nose, pharynx, larynx, trachea, bronchi, and the bronchioles. The terminal servings of the air passages- the respiratory bronchioles and alveolar ducts- sub-serve the function of gas exchange. The part above the vocal cords is termed the upper respiratory tract and the parts below are called the lower respiratory tract.
The trachea which is 11cm long is retained permanently open by the occurrence of C-shaped cartilages on its wall. A number of mucous glands within the mucous membrane provide mucus which moistens the top and takes part in ciliary action. The trachea divides in the right and remaining bronchi. The bronchi are similar to the trachea in structure. The right main bronchus is 1-2. 5cm long and it is in direct line with the trachea. This fact makes it more vulnerable for obstruction by foreign bodies entering through the trachea. The right main bronchus divides into branches which give you the right upper lobe, middle lobe, and lower lobe. The left main bronchus is longer (5cm) and it forms an angle of 50-100 degrees with the right main bronchus. It divides into two branches which source the upper and lower lobes. Further division of the lobar bronchi gives rise to segmental bronchi which supply bronchopulmonary segments.
The bronchopulmonary segment is a wedge of lung tissue offered by each segmental bronchus along with the related branches of the pulmonary artery and vein. The bronchopulmonary segments act as independent units and are separated by fibrous septa.To become more data click here medicos a domicilio.
Divisions of the bronchial tree:
After 8-13 effective divisions the segmental bronchi split up into the most compact bronchi. They continue further as bronchioles. The bronchioles have no cartilage and mucous glands on their wall space. The bronchioles divide further and the terminal bronchioles divide further and the terminal bronchioles are formed after the fourth division. The terminal bronchioles produce respiratory bronchioles. Alveoli get started to appear on the walls of the respiratory bronchioles. As the respiratory system bronchioles divide further, the number of alveoli as a result of them progressively increases. Normal adult lung contains about 300 million alveoli. Quick division of the respiratory bronchioles results in enormous increase in surface area. The terminal portions of the respiratory bronchioles divide into alveolar ducts and cartable. Alveoli sacs. Alveoli are 0. 1-0. 2mm in diameter. Up to the respiratory bronchioles the breathing passages only conduct air passively, but beyond this they, also take part in gaseous exchange. The part supplied by a single terminal bronchiole is called an "acinus". An alveolar duct with its distal cable connections is called a "primary lobule". A group of primary lobules separated by connective tissue septa form a "secondary lobule".
Follicles of Kohn and Pathways of Lembert:
Pores of Kohn are openings linking alveoli, which allow communication between them and occasionally between adjacent segments. Canals of Lembert are short communications lines by epithelium which exist between distal bronchioles and some of the neighboring alveoli. These take part in collateral ventilation between different regions of the lung.
The liner of the trachea, bronchi, and bronchioles involves ciliated columnar epithelium containing goblet cells. The respiratory bronchioles are lined by non-ciliated cuboidal epithelium. The lining epithelium of the alveoli is flattened and it consists of two types of cells- type We and type II pneumonocytes-arranged on a basement tissue layer. Type I pneumonocytes are numerous and they cover the majority of the inner surface of the alveoli. Gas exchange occurs mainly across these cells. Type II pneumonocytes are smaller in number. They contain lamelleated osmiophilic inclusion bodies which are thought to be of lysosomal nature. Surfactant is produced or stored in them.To get additional facts click the link Geriatra a domicilio.