Lung Ventilation

Question 1

Explain the process of Inspiration in the lungs

Answer 1

Diaphragm contracts and moves down to become flat.
If more oxygen required, for example, when excising, external intercostals contract and move rib cage upwards and outwards. Volume of the thoracic cavity (Chest) increases. Pressure decreases in the lungs compared to the outside, air rushes in.

Question 2

Explain the process of Expiration in the lungs

Answer 2

The elastic fibres in the alveoli shrink, increase pressure and air is squeezed out.
When we are exercising, internal intercoastals contract and move rib cage inwards and downwards. Abdominal muscles contract and the stomach and liver push diaphragm back so it is domed again. Volume of thoracic cavity (Chest) decreases. Pressure will increase and air rushes out.