|The Anatomy And Physiology Of The Respiratory System|
The right lung has three lobes derived from the division of the right main bronchus. The left has two lobes from the divisions of the left main bronchus. The oblique fissure divides the left lung into an upper and a lower, The right lung is divided into two by the oblique fissure too but the lung portion above is subdivided into an upper and a middle lobe by the transverse fissure.
The trachea begins at the cricoid cartilage and ends at the level of the sternal angle where it bifurcates into the two main bronchi-the right and the left main bronchi.
- bony partition
- nasal cavity
- mouth cavity
- (Adam’s apple)
- voice box (larynx)
- Throat (pharynx)
- pleural fluid
- lung position of heart
HUMAN RESPIRATORY SYSTEM:
The respiratory tract extends from the nostrils to the terminal bronchioles. It is divided into upper and lower respiratory tracts. The upper portion includes the nasopharynx, the larynx, and the trachea. The lower portion comprises the bifurcation of the trachea into the right and left bronchi to the level of the terminal bronchioles. The entire respiratory tract is ciliated and is covered by a thin film of mucus.
The right main bronchus is more vertical than the left. It is therefore usual for foreign bodies to lodge in the right main bronchus. The right main bronchus gives off the upper lobe bronchus, the middle lobe bronchus, and the lower lobe bronchus. The left main bronchus, on the other hand, gives off the upper lobe bronchus and the lower lobe bronchus. It does not have a middle bronchus
The basic functional unit of the lung is called an acinus. acinus contains branching respiratory bronchioles that communicate with clusters of alveoli. It is in the alveoli that the exchange of gases takes place. The alveoli are bathed with surfactant which reduces its surface tension and thus prevents alveoli collapse.