"Animal Physiology: From Genes to Organisms" (primarily known as the textbook by Sherwood, Klandorf, and Yancey) is built around the .

A standout informative feature of this approach is its . Rather than looking at organs in isolation, it connects biological functions across four distinct layers:

How specific gene expressions trigger the production of proteins and enzymes.

How individual tissues coordinate to perform complex tasks (like respiration or digestion).

This "bottom-up" perspective helps explain why an animal functions the way it does, linking microscopic instructions in DNA to the macroscopic behavior of the whole animal.

How those proteins govern cell signaling and metabolism.