It is possible to have multiple independent variables and/or multiple dependent variables. For instance, in multivariable calculus, one often encounters functions of the form, where z is a dependent variable and x and y are independent variables.
Gas exchange between the air within the alveoli and the pulmonary capillaries occurs by diffusion. The oxygen must first dissolve before passing through the respiratory epithelium. Gas moves from a region of high partial pressure to a region of low partial pressure, down a partial pressure gradient.
Conclusion Questions 3.3.1 1. The walls of the alveoli in the lungs are incredibly thin. Explain how this structure is related to function in the body. The walls of the alveoli are extremely thin so that they can serve their purpose of allowing diffusion of oxygen and carbon dioxide to happen. This is where gas exchange occurs.