The coronal reformat of a CT scan of the abdomen shows the tree like structure of the small bowel. The original scan is rotated 180 degrees so that the tree stands upright. The branching pattern is derived from the arterial supply and the venous drainage of the bowel and form the trunk and branches. The contrast filled loops of small bowel form the leaves. The portal vein and splenic vein form the roots of the tree.
The blue sky, and the earth below together with the connections to the liver (purple structure) and spleen (orange structure) provide nourishment and sustenance. The roots provide transport and nourishment from the earth and the trunk and branches provide a transport system to the leaves.