Physics of the lung and breathing

Objectives:
1. To get information about anatomy of respiratory system.
2. To get information about removal of inhaled particles.
3. To get information about measurement of lung volumes.
4. To get information about physics of alveoli.
5. To get information about physics of common lung diseases
Anatomy of respiratory system
1.The air ways:
• The respiratory system is divided into upper and airways
– The upper airways consist from nose, pharynx, larynx and associated structures
– Lower Airways involve trachea, bronchi, and lungs
There are two lungs :Right lung consists from three lobes while the left lung consists of two lobes.
Pulmonary interstitial tissues include elastin, collagen fibers, lymphocytes, plasma cells, and mast cells.
The air passes through windpipe (trachea), each bronchus divide multiple times (about 15 times) until it reach to a sac like structure called alveoli of 0.2mm diameter and 0.4 ?m wall thickness, each alveolus surrounded by blood capillary. So O2 can diffuse from alveolus into RBC and CO2 diffuse from blood into air in the alveolus.
2.Removal of Inhaled Particles
With its surface area of 50 to 100 square meters, the lung presents the largest
surface of the body to an increasingly hostile environment. Various mechanisms for dealing with inhaled particles have been developed.
Large particles are filtered out in the nose. Smaller particles that deposit in the conducting airways are removed by a moving staircase of mucus that continually sweeps debris up to the epiglottis, by the moving cilia, where it is swallowed or coughed up. Each cilia vibrates about 1000 times a minute. The mucus moves 1-2 cm/min (1 mile/week). Cilia as escalator system of trachea. It takes 30 min for particle of dust to be cleared out of the bronchi and trachea into throat where it is expelled or swallowed.