‫المحاضرة‬
‫الرابعة‬
9-THE LUNGS
The lungs are paired organs in the chest that perform
respiration. In human, there are two lungs each one
is present at one side in the thoracic cavity. The right
lung has 3 lobes an 2 fissures, while the left has two
lobes and one fissures.
Function of lungs against damage:
1. Filtration action of the respiratory passages.
2. Secretion of mucus by mucosa of air passages. It
acts as a trap for foreign particles and bacteria.
3. Cough reflex.
4. Sneezing reflex.
5. Moistening of dry air and buffering of excessively
hot or cold air.
6. Peristaltic movement of bronchioles driving foreign
particles to larger passages.
7. Movement of cilia of respiratory mucosa drives
mucus with its trapped particles to the pharynx
where it is coughed or expelled.
9. The tonsils have a protective function against bacteria.
10.The presence of a thin layer of fluid between the
parietal and visceral layers of pleura acts as a lubricant.
10-The pleura
It is a thin double-layered protective serous membrane
covering the lungs.
1. The parietal pleura
2. The visceral pleura
The blood supply of the lungs:
Lymphatics :
The lymphatics of the lung fall into two main divisions :
1. A superficial set : present in the pleura.
2. A deep set : in the pulmonary parenchyma