Discribe the mechanism of respiration in human beings.
In human beings, the air is taken into the body through the nostrils. From here, the air passes through the trachea and brochi into the lungs. Trachea does not collapse even when there is no air in it because it is supported by rings of soft bones called cartilage.
Within the lungs, the bronchi divides into smaller and smaller tubes which end up into sac-like structures called alveoli. The alveoli provide a largesurface area where the exchange of gases can take place as the walls of the alveoli contain an extensive network of blood-vessels.
When we breathe in or inhale, the ribs expand and the diaphragm flattens which increases the size of the chest cavity and the air is filled into the lungs. The blood brings carbon dioxide from the rest of the body� and the oxygen is taken up by blood and carried to all the cells of the body.