In TCM theory they represent the energetic representation of the internal organs rather than the anatomical viscera that is referred to in Western medicine.
To understand the zangfu it is important to realize that their concept did not primarily develop out of anatomical biological considerations but from cosmological patterns and influences.
The need to describe and systematize the bodily functions was more significant to ancient Chinese physicians than opening up a cadaver (dead body) and seeing what morphological formal structures there actually were.
[6] Since the concept of the zangfu was developed on the basis of wuxing philosophy, they are incorporated into a system of allocation to one of five elemental qualities (i.e., the Five goings or Five Phases).
[7] The correspondence between zangfu and Five Elements are stipulated as: The zang organs' essential functions consist in manufacturing and storing qi and blood (and, in the case of the Kidney, essence).
The hollow fu organs' main purpose is to transmit and digest (传化, pinyin: chuánhuà) substances (like waste, food, etc.).
In listing the functions of the zang organs, TCM regularly uses the term "governing" (主; zhǔ) – indicating that the main responsibility of regulating something (e.g. blood, qi, water metabolism etc.)
A properly functioning Lung organ will ensure the skin and hair are of good quality and that the immune system is strong and able to fight disease.
The concept of the zangfu is not identified by evidence based medicine – the underlying assumptions and theory have not been verified or falsified by controlled experiments.