Question

Why our lungs expand during inhalation?

Answer 1

due to entry of oxygen in our lungs

Answer 2

When you breathe in, orinhale, your diaphragm contracts (tightens) and moves downward. This increases the space in yourchest cavity, into whichyour lungs expand. The intercostal muscles between your ribs also help enlarge the chest cavity. They contract to pull yourrib cage both upward and outward when youinhale.