Final answer:
Getting punched in the abdomen disrupts the diaphragm’s normal contraction and relaxation pattern, which is necessary for breathing. This can prevent the diaphragm from drawing air into the lungs, causing a temporary loss of breath.
Step-by-step explanation:
Explain why getting punched in the abdomen knocks the breath out of you: Breathing involves the diaphragm, a large muscle beneath the lungs that contracts and moves down, creating negative pressure inside the lungs and allowing air to enter. When the diaphragm contracts, the volume of the chest cavity increases and the air pressure within the lungs decreases, causing air to rush in. Conversely, when the diaphragm relaxes, it pushes up against the lungs, the chest cavity volume decreases, and the pressure inside the lungs becomes greater than the outside air pressure, which forces air out.
When someone is punched in the abdomen, this sudden force can cause an involuntary contraction of the diaphragm while it's in the middle of its breathing cycle. This disrupts the normal rhythm of contraction and relaxation that facilitates breathing. Particularly, if the punch occurs during an inhalation, it can prevent the diaphragm from moving downwards as it typically would to draw air in, effectively 'knocking the breath out' of the individual. Because the diaphragm is momentarily unable to control the pressure difference necessary for respiration, you’re left temporarily breathless.