The functions of the Spleen energies are disordered easily – mainly digestion and holding blood/tissues and organs in place.
The Spleen Qi also co-governs the metabolism and hence the immune system.
When depleted, the body can fall over many different ways – hopefully not all at once.
Please also look at Spleen Qi in health and when Yang Qi deficient – as they are all variants of the same life continuum.
To understand more, start with the apps – solutions for questions you may not have thought to ask – or that no one could answer . . there are also various books in the resources here