Today Biology is being revolutionized by rapid advances in molecular biology and genomics. At the international level, physiologists and professional societies are calling for integrative teaching. For example, the Urinary System in most texts is a stand-alone chapter. This is NOT a human course, because this course is designed to foster broad biological thinking. Therefore I will use non-human examples in all sections of the course to supplement this text.
Organisms are the product of millions of years of evolution.
E.g., the human spine is stiffly-jointed, moderately flexible support for the middle and upper body, made of bone, cartilage, etc. 2. E.g., the vertebrate spine first evolved in proto-fishes as a flexible attachment for swimming muscles. One consequence is that bodies are not always logically designed, but are the product of historical compromises. Just look at all the mild to severe spinal problems humans have from our recent evolution into an upright stance. This explanatory duality has often profound implications for understanding of anatomy and physiology, yet in the past it's often been ignored.