Name and describe the process that leads to air entering the lungs

This process is called Ventilation and is a required step in aerobic respiration.This process starts with the diaphragm contracting, one also sees the (external) intercostal muscles contract. These contractions lead to the ribcage moving up and outwards and increases the volume of the thoracic cavity. This volume increase in the thorax and lungs results in a reduction of air pressure in the lungs. The reduction in lung air pressure leads to the outside air pressure being greater, therefore to reduce the difference in pressures air enters the body through the oral cavity and enters the lungs.