Here is a link to a series of articles that outlines Steiners view of the structure of Life.
The main chapters are the first two, but the other look very interesting.
An Introduction to Anthroposophical Medicine. 7 Rudolf Steiner
The Members of Being in Man and Nature:
The Fourfold Kingdoms of Nature/Man and Plant. 14 Wilhelm Pelikan
Archetypes of Form in the Human Organism . 28 Ira Cantor