The functional unit of the kidney is nephron. Kidney comprises two kinds of nephrons, each situated in distinct sections of the renal cortex, that is, juxtamedullary nephrons and cortical nephrons. A nephron constitutes of a renal tubule, renal corpuscle, and the associated network of capillaries. The nephron is accountable for eradicating waste from the body.
The functional unit of lungs is alveoli. They resemble a cluster of grapes, they are thin and possess moist walls. They are a single layer of cells enveloped by a layer of capillaries. The main function of the lungs is respiration. The alveoli help one to breathe, by conducting the process of gas exchange.