on 24-Sep-2017 (Sun)

The trachea serves as a conduit for ventilation and the clearance of tracheal and bronchial secretions.

The trachea bifurcates at the carina into the right and left main stem bronchi.

the diaphragm, and, to a lesser extent, the external intercostal muscles are responsible for inspiration;

he distance from the tracheal carina to the take-off of the right upper lobe bronchus is an average of2 .0 cm in men and approximately 1.5 cm in women.

he sternoclei- domastoid, scalene, and pectoral is muscles can be recruited during inspiration.

Exhalation may be facilitated by the abdominal muscles (rectus abdominis, external and internal oblique, and transversus) and perhaps the internal intercostal muscles- aiding the downward move- ment of the ribs.

The left main stem bronchus is longer

Diaphragmatic movement normally accounts for 75% of the change in chest volume.

Contraction of the diap hr agm- t he principal pulmonary muscl

Expiration is normally passive in the supine position, but becomes active in the upright position and with increased effort.

cricoid carti- lage is the narrowest part of the trachea,

Humidificati on and fi lt ering of inspired air are functions of the upper airway (nose, mouth, and pharynx).

function of the tracheobronchial tree is to conduct gas flow to and from the alveoli.

tracheal bifurcati on located at the level of the sternal angle

Gas exchange can occur only across the flat epithelium, which begins to appear on respiratory bronchioles

Loss of cartilaginous support causes the patency of smaller airways to become dependent on radial traction by the elas- tic reco il of the surrounding tissue; as a corollary, airway diameter becomes dependent on total lung volume.

pright posi- tion, the largest alveoli are at the pulmonary apex, whereas the smallest tend to be at the base. With inspiration, discrepancies in alveolar size diminish.

Alveofar size is a function of both gravity and lung volume.

he pulmonary interstitial space contains mainly elastin, collagen, and perhaps nerve fibers.

Gas exchange occurs primarily on the thin side of the alveolocapillary membrane,

Type I pneumocytes are flat and form tight

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