Answer:
During inhalation in mammals, four main actions occur:
1. The diaphragm muscle contracts and moves downward, creating more space in the chest cavity.
2. The intercostal muscles between the ribs contract, causing the rib cage to expand.
3. The expanding chest cavity lowers the pressure inside, drawing air into the lungs.
4. Air can enter through the nose or mouth, with the nasal passages helping to filter and warm the air before it reaches the lungs.
These actions work together to bring fresh air into the lungs, providing oxygen for respiration.