Nature + Physiology
One of the beautiful things about Chinese medicine theory is that it is truly a medicine based in the observation of our relationship with nature.
For instance, Springtime is easily seen as the birth phase, which begins when the sprouts begin pushing up through the ground. Early summer is seen as the growth phase, where the buds begin to open and flourish. Late summer is maturation, where the flowers and plants have grown to capacity and finally begin to ripen and rot. Autumn is decline, where leaves fall from the trees and nuts cover the ground. Finally, winter is seen as the storage phase, where seeds go deep and prepare for another cycle.
This cycle is also seen in the functioning/physiology of the body. We take “life” in through the air we breathe, the food we eat, and the water we drink, and it is transformed into blood and fluids. It is blood and fluid through which all functioning is possible. Transformation and communication are happening between all of the organs and channels all the time, and the generation cycle of birth, growth, maturation, decline, and storage is constant in the body.
The broad strokes of physiology through the lens of Chinese medicine are as follows: The Fire of life is consolidated and stored in the kidneys, and this mix of fire with digested food is steamed up through the digestive system to the liver. The digestion must have enough fire under it to steam the good stuff up to the liver. The liver must be strong enough to start the cycle, clean the blood, and send it along to the lungs. The lungs must have the right amount of moisture and strength to oxygenate the blood. The heart must have enough oomph to circulate the blood through the arterial and venous systems, and then we are back to the kidneys, which must have the appropriate mix of Fire within Water to consolidate and hold the energy, and discard what is not useful. (This explanation is intended only to provide the broad strokes of physiology through the lens of Chinese medicine.)
This birth, growth, maturation, decline, storage cycle is happening every minute of every hour of every day of your life. The cycle renews with each breath you take, sip of water you drink, and meal you eat. How you feel and how you function (sleep, appetite, digestion, energy level, mood, etc) is a reflection of how your system is functioning.