Describe the events that occur during the process of breathing in humans.

(N/A) Breathing in humans consists of two main phases:
$1$. $Inhalation$: The external intercostal muscles contract, lifting the ribs upward and outward. Simultaneously, the diaphragm contracts and flattens, moving downward. This increases the volume of the thoracic cavity, creating a lower pressure inside the lungs compared to the atmosphere, causing air to rush in.
$2$. $Exhalation$: The intercostal muscles and diaphragm relax. The diaphragm moves upward into its dome shape, and the rib cage moves inward and downward. This decreases the volume of the thoracic cavity, increasing the pressure inside the lungs, which forces the air out of the lungs.