The Spleen is central Organ in production of Qi.
Called the "Foundation of Postnatal existence". Extracts Food Qi (Gu Qi) from food and liquids taken into Stomach. Food Qi is basis for formation of Qi and Blood.
Spleen is central Organ in production of Qi. Stomach "rots and ripens" ingested food and drink, and prepares the way for the Spleen which separates and extracts the GU Qi (food Qi) and refined essence from the digestate.
Food Qi goes upward to the Lungs in the Upper Burner. Food Qi combines with air to form Zong Qi and goes to the Heart to form Blood. Flavors are distributed to the various organs, sweet to the Spleen, salty to Kidney, bitter to Heart, sour to Liver, pungent to Lung.
Spleen also separates usable from unusable fluids ingested. Pure "clear" part goes upwards to the Lungs for distribution to the skin. "Turbid" part goes to Intestines for further separation.
In health, transforming and transporting function of Qi ensures good digestion, good appetite, normal absorption, regular bowel movements. Impaired function, poor appetite, bad digestion, abdominal distention, loose stools.
When transformation/transportation of fluids impaired, fluids can accumulate to form Dampness and then Phlegm.
"The Spleen likes Dryness and hates Dampness". Its transformation and transportation function can be impaired by Damp e.g. Damp-forming foods like salads, dairy, etc.
Spleen Yang, essential to the process, impaired by excessive consumption of cold liquids (esp. ice water, ice cream, etc.) Conversely, Deficient Qi or Yang of Spleen can CAUSE internal Dampness.
If Spleen Qi is healthy, Blood circulates normally (also see Liver) and stays in vessels.
In Deficient Spleen Qi or Deficient Spleen Yang, Blood may spill from vessels. i.e. - Hemorrhages, subcutaneous bleeding, etc. (petechiae, purpura)
Also, especially lower body hemorrhage, i.e. - Metrorrhagia can be caused by Xu Spleen Qi.
(Food Qi extracted by Spleen sent to Lung and to Heart to form Blood with assistance of Yuan Qi from Kidney). To tonify Blood, always tonify Spleen.
Food Qi eventually goes to nourish all tissues in the body, transported throughout body by Spleen. Particularly directed to the muscles. Weak Spleen Qi: fatigue, muscles weak or even atrophied. Tonify Spleen in fatigue.
Opens to the Mouth and Manifests in the Lips - When food enters mouth, chewing prepares food for transformation and transportation. Therefore Spleen related to mouth. Normal Spleen Qi; good sense of taste and moist pink lips.
Is residence of I (Yi). Influences our capacity for thinking, studying, concentration, memorizing, etc. Weak Spleen Qi; thinking dull, poor concentration, poor memory, etc. Excessive studying, mental work etc., weaken Spleen.