Question : Describe the mechanism of breathing in man.

1.	Question : Describe the mechanism of breathing in man.
Answer» Solution :Breathing is a physical process INVOLVING inflow (inspiration) and outflow (expiration) of air between atmosphere and the ALVEOLI of the ling. During inspiration,the intercostalmusclescontract and pull the RIB cage upwards and outwards. At the sametime, the diaphragm contracts and flattens. These movements increase the volume and thereforelowersthe pressure in the thorax/chest cavity . As the pressure in the chest cavity FALLS belowthatof the atmosphere, airrushes in. During expiration (breathing out), relaxation of intercostal muscles and diaphragm takes place. The ribs move downwards and inwards. The volume of the lungs decreases, squeezingthe air inside them. Diaphragm comes back to its ogiginal C-shaped position. This increases the airpressureinsidethe lungs, forcing it out.

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