Enzymes and acidic juices in the stomach, which breaks proteins down into smaller molecules, is known as

The answer is; Pepsin

Pepsin is first secreted by the chief cells of the stomach wall and the inactive precursor called pepsinogen. When pepsinogen interacts with the acidic environment of the stomach due to hydrochloric acid, it is turned to pepsin. The pepsin breaks down large protein molecules to smaller molecules.

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.