The lung expands when it gets full of air , so the chest needs to do the same ,because if it didn't the lungs wouldn't fit in there when they get full , and that would be a terrible mistake of our body.
The tempting answer would be that the chest cavity grows in volume/capacity with inhalation and then decreases in volume/capacity with exhalation. But there is a slight argument over semantics and chronology to be made. The question and answer, as it is, makes an implication that the changes in volume are a result/effect of inhalation and exhalation. But it is, in fact, the opposite.
The diaphragm lowers and pushes down on the digestive organs while the rib cage shortens and pushes out. These actions increase the volume of the thoracic (chest) cavity, where the lungs are. If you have taken a Chemistry course, then you will remember the ideal gas laws regarding volume and pressure. If you increase the volume of a space (thoracic cavity) while keeping the amount of air in this contained space (lungs) constant, then there will be negative pressure. This lack of pressure in the lungs and higher ambient pressure causes air to rush into the lungs, completing inhalation.
As you can see, the chest cavity increases in volume before inhalation. The same principles work in the opposite direction during exhalation.
the lower air pressure in the lungs causes air to rush into the lungs.
As you breath in you take air into your lungs and your chest expands, so to answer your question 'Your chest gets bigger'
Its just expand
Normally it increases.
The movement of the diaphragm affects the size of the chest cavity by when you inhale the chest cavity enlarges, but when you exhale the chest cavity becomes smaller.
You can not know the position of diaphragm, when you inhale or exhale. The position of the diaphragm changes automatically.
you inhale when your diaphragm contracts.
the diaphragm. It is right above the heart and lungs, and expands and contracts when you breathe in and out. You can almost feel it move down a little, when you release air.
When the Diaphragm contracts, it is pulled down, and is pulled back up when it relaxes.Also, when you inhale, it contracts. When you exhale, it relaxes.
When you inhale, your diaphragm contracts and moves downward, and when you exhale, your diaphragm relaxes and moves upward.
inhale
Your diaphragm IS muscle. When we inhale, it is pushed down. When we exhale, it is pulled up.
When the diaphragm contracts and moves lower, the chest cavity enlarges, reducing the pressure outside the lungs. To equalize the pressure, air enters the lungs. When the diaphragm relaxes and moves back up, the elasticity of the lungs and chest wall pushes air out of the lungs.
diaphragm
Inhalation requires the contraction of the diaphragm, and exhalation occurs when it relaxes.
answer: diaphragm at the bottom of the chest cavity is a muscle called the diaphragm. when the diapragm contracts, the chest cavity becomes larger.