I asked Cathy to respond to your question because she is a real student of TCM (you can read one of her articles about the 5 elements and the seasons here
. The rest are under the tab Articles
.) Here are her thoughts for you:
Hello Frank, I will try my best to answer your question as simply as possible.
In TCM theory when we are discussing an organ we are not just speaking of its anatomical location and function, we are speaking of a particular 'system'. The body cannot be deduced into parts but rather functions as an integrated whole. Organ theory maintains that there is a relationship between the organs and the tissues and sense organs of the body. This may be through the trajectory of the organs meridian, the energetic function of the internal organs and organ related patterns/disharmonies. Our organs are even associated with certain emotions, seasons, elements, sounds, tastes... In TCM the organs have a much wider range of activities as compared to Western medicine.
For example if we speak about the Spleen/Pancreas & Stomach, according to TCM theory these are the organs of digestion. The Stomach breaks down our food and the Spleen/Pancreas transforms and transports the essence from the food to provide nourishment for the body. If the body is well nourished then our muscles and limbs will be strong. The Spleen/Pancreas is the primary organ responsible for the production of qi & blood which is created from the foods we eat. Therefore if we don't consume good food or if our Spleen/Pancreas is weak we do not produce enough blood or Qi we will feel tired, possibly have digestive issues, poor appetite, bloating, loose stools etc... Therefore the Spleen/Pancreas has an important role in producing blood and keeping it in its blood vessels. Any weakness can be reflected in the blood spilling from its pathways causing bruising, hemorrhoids, uterine bleeding etc...
The Lungs have to do with our respiratory and immune system. Through its role in dispersing energy throughout the body by oxygenating our blood our Lungs have an important function for all the organs and tissues of the body. When our lung Qi is weak our whole body may feel tired. The lungs dominate our skin (and sweat glands) and body hair in that they disperse qi and body fluids to keep our muscles, skin and hair moist. When our lung qi is weak we may have dry skin, respiratory issues or a weak immune system.
The Kidneys...these guys have a broad range of functions and are one of the most important organs. They store our 'Jing' which is our essence. We acquire this essence in part from our parents at conception and in part from the foods we eat. Because they store our 'Jing' they are responsible for our development and our ability to produce. Kidneys control the bones in that stimulate the production of bone marrow which is an important function of mental development, brain function and hair growth. The health of our kidneys can be reflected in the quality of our hair. Pre mature greying may indicate weak kidney Qi. Other symptoms related to the Kidneys can be back pain, bone and joint problems, infertility, poor memory...to name a few.
The Liver stores blood and ensures the proper circulation of Qi and blood in the body for movement and digestion (secretion of bile) and also the smooth flow of our emotions. Emotions are a form of Qi (energy). If the liver function is disturb in any way it could result in feelings of depression, frustration, anger etc... The liver controls the tendons/muscles and opens into the nails because without the smooth flow of Qi and blood which actuality means nourishment we can have tendon problems, muscle spasms and/or brittle nails. The liver opens into the eyes partly because of its nourishing quality and because of its meridians pathways. Any dysfunction can cause night blindness, blurry vision, red eyes...
And finally the Heart is responsible for the power and volume of our blood. The hearts brilliance is manifested in the face and because the face is so vascular we can often tell the state of our blood from our complexion and therefore the state of our heart qi. The heart also stores our 'Shen' (consciousness, spirit) and so any problems with our heart Qi can cause palpitations, insomnia, anxiety, lack of joy...
So as you can see for example our blood and muscles are influenced by many organs in various ways. I know this is a lot of information but I hope it is able to shed a little light on some of your questions. It can definitely be confusing but you have to remember that all these internal organ systems are so intimately connected and although they have specific functions they all rely on one another for our optimal well being. Our meridian system plays a big role in this interconnectedness. If you are interested in expanding your curiosity of Chinese Medicine as Jessica mentioned you might want to pick up 'The Web that has no Weaver' by Ted Kaptchuk, he provides good and accessible information for anyone interested in understanding TCM a little deeper.