Known as the 'Minister of Power', the kidney is regarded as the body's most important reservoir of essential energy. The original prenatal energy (yuan chee) which forms the basis of life is stored in the kidney organ-energy system, which is why the kidneys are also known as the 'Root of Life'.

The kidney organ system also includes the adrenal glands. It also includes what the Chinese call the 'external kidneys': the testicles in men and the ovaries in women. Thus the kidneys control sexual and reproductive functions and provide the body's prime source of sexual vitality.

The kidneys themselves are responsible for filtering waste metabolites from the blood and moving them onwards to the bladder for excretion in urine. Along with the large intestine, the kidneys control the balance of fluids in the body. In addition, they regulate the body's acid-alkaline balance (pH) by selectively filtering out or retaining various minerals.

The kidneys control the growth and development of bones and nourish the marrow, which is the body's source of red and white blood cells. Weak kidney energy is therefore a prime cause of anemia and immune deficiency. The Chinese view the spinal cord and the brain as forms of marrow, and therefore poor memory, inability to think clearly, and backache are all regarded as indicators of impaired kidney function and deficient kidney energy.

Kidney vitality is reflected externally by the condition of head and body hair and is associated with the aperture of the ears. Tinnitus (ringing ears) is thus a sign of kidney dysfunction.

The kidneys are the seat of courage and willpower, and therefore any impairment in kidney energy results in feelings of fear and paranoia. Intense fear can cause involuntary urination.

The Kidney's positive psycho-emotional attributes are wisdom, rationality, clear perception, gentleness, and self-understanding.

The negative attributes are fear, loneliness, insecurity, and shock (which attacks the Heart first then descends into the Kidneys to become fear).

Functions stores prenatal essence, filters the blood

The Marrow produced from the Kidney Jing flows into the brain. The thinking ability is strengthened when Qi and Blood in the cerebral cortex are abundant. With the increase of thinking activity, a circle of light develops within the body's Taiji Pole. The individual's innate intelligence (Yuan Shen) is represented by the intensity of light. The degree of accumulated spiritual energy is reflected by the number of light circles developed within the Taiji Pole. These circles of light can be best observed when first waking. By placing slight pressure of the external eye lids the inner light of the Taiji Pole is projected onto the optic nerves, reflecting an image of the circle of light. If the circle of light is complete, it reflects a strong, healthy condition. If the circle of light is dark within its center (similar to a doughnut), this reflects a Deficient condition. If the circle of light is broken or interrupted, it reflects an extreme Deficiency.

The "memory zone," as well as the "thought center" are also located in the cerebral cortex and will not develop until the Kidney Channels travel through the spine, along with the Liver Channels, to reach the cortex. When the Qi of these two channels is abundant, the memory function is keen.

The Kidneys house the body's will power (Zhi). They control short-term memory and store data. The Kidneys provide the capacity and drive for strength, skill and hard work. A patient with strong Kidneys can work hard and purposefully for long periods of time. Consequently, when the Kidneys are in a state of disharmony, the patient can sometimes be driven to a state of excessive-compulsive working habits (a workaholic). A patient with weak Kidneys will lack strength and endurance.