So almost all the biology that we observe can be thought of as a series of problems and their corresponding solutions, and the first problem that every organ must solve is a continuous supply of nutrients to fuel all those cells of the body.
Skoro sva biologija koju promatramo može se promišljati kao niz problema i niz odgovarajućih rješenja, a glavni problem koji svaki organ mora riješiti jest konstantna opskrba svih tih stanica hranjivim materijalima.