What is the significance of Taiyang?
Taiyang refers to the sun and is still used interchangeably with the sun in modern Chinese. Taiyang, among all yang, is the heart; the heart is the ultimate yang; hence, it is referred to as Taiyang. In terms of its implied connotations, Taiyang signifies magnificent or grand yang - when the yang qi is grand, we refer to it as Taiyang.
The leg Taiyang channel corresponds to the urinary bladder, and the Taiyang channel of the arm corresponds to the small intestine, both of which are hollow bowel-type organs.