In response to a threat, we perspire, breathe more quickly, get goose bumps, and feel nauseous. These responses are controlled by the nervous system.

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.

bradykinin is a physiologically and pharmacologically active peptide of the kinin group of proteins, consisting of nine amino acids.