Respiration is the physical act of inspiration and exhalation of oxygen. Gas exchange is what happens in the lungs to use the oxygen that is brought in and expel the Carbon Dioxide brought back into the lungs from the cells. Respiration is the physical act of inspiration and exhalation of oxygen.
Definition of polyphony. : a style of musical composition employing two or more simultaneous but relatively independent melodic lines : counterpoint.
A good example of good polyphony is the 3rd movt of Mahler's 9th symphony. Here is a link to hear this movt. Try to listen for the different voices all going at the same time. It's genius.