Final answer:
When you breathe in, the diaphragm contracts and the ribcage moves up and out, creating more space for the lungs to expand.
Step-by-step explanation:
When you breathe in, the diaphragm contracts and the ribcage moves up and out. The diaphragm is a sheet of muscle that sits below your lungs and helps with the process of breathing. When it contracts, it moves downward, creating more space for the lungs to expand. At the same time, the ribcage also expands, allowing the lungs to take in more air.
Learn more about Breathing