Our Bodies are Houses with many Rooms

   When we think of our bodies, we think of all of the various parts that built up from that original egg and sperm that started the process of dividing, growing, and specializing. From that beginning, we end up with a set of systems which allows us to stand, move, breathe, eat, and do the other functions of everyday living. These systems work together to make it possible for us to live and reproduce.

   But, our bodies are NOT just composed of the cells that were created as part of growing and life. Our bodies provide an environment for many other living organisms -- some hostile but many of great benefit to our everyday lives. For many years, medical researchers have just noted the facts of their existence (and, sometimes, blindly tried to eliminate them) and had no real idea of just how they interact with the rest of our bodily functions. This is now changing and active research is being done. Note that this research is still young in experience and knowledge and many interactions and functions are still unknown.

   An organism can exist anywhere within our body but we will focus on four areas that are of specific interest. These include the interior cell, the skin, the mouth, and the digestive tract. Within the interior cells exists organisms called the mitochondria (one of such is called a mitochondrion). While these "organelles" are an important mechanism to supply energy to the human cell (and, thus, to the human body), they also have many other functions within the body.

   The mitochondrion reproduces independently from the other cells of the human body. It exists only within the egg (and not the sperm) and thus, inheritance of the mitochondria within a body is based on maternal lineage (mother to child). The separation between egg and sperm and its independent reproduction gives it a likelihood of being considered an endosymbiont. In other words, at some point in the past the mitochondria took up residence within human (and other animals) cells and act as cooperative parts of the cell.

   On the surface of the skin (even the very "cleanest" of skin), exists a wonderland of tiny animals, bacteria, and other living creatures. The exact interplay between these creatures and their environment (the skin) is still to be fully understood but it is recognized that they do play a part in keeping the body from being invaded by unwelcome visitors. Of course, within this dermal ecosystem is the possibility of undesirable inhabitants -- such as fungus that creates "athlete's foot".

   There is a large difference between the mitochondria living peacefully within the cell and the exposed environment of the skin -- a large, direct, interaction with the exterior world. Showers, baths, perfume, makeup, dirt, and so forth will affect the living environment on the skin. How does it affect it? We don't really know but two people (let's say they are identical twins to make this simpler) who have different exterior living environments, diets, and exterior habits will have different sets of creatures (or, at least, different proportions) on the skin -- which is likely to affect some aspect of health and protection from exterior invasion.

   Our mouths harbor a large collection of bacteria and other living matter. This environment can be altered by both external and internal processes. Cleaning teeth and gums can reduce the amount of bacteria and their by-products. Blood sugar levels (especially relevant to those with diabetes) can alter the number and type of bacteria living in the mouth. (Note that brushing, diet, gum health, and blood sugar levels can all change the smell of your breath.) Many oral bacteria have potentially bad effects -- but controllable -- and, presently, few beneficial effects are known.

   The area of symbiosis of greatest present interest is the world of the digestive tract. Although it has long been known that interior bacteria can be directly involved with digestion -- for example, termites have special bacteria that allow them to digest cellulose (wood fiber) -- it was not known that the same was true with humans and other animals. It turns out that the composition of the neighborhoods of our digestive system can affect hormones, immune system, metabolism, allergies, blood sugar levels (not just insulin and sugar), mood, and other matters.

   Just how, and what, makes a difference is still unknown but the knowledge that it makes a difference is truly exciting -- in reality the addition of an entirely new bodily system. This infant study, of course, gives rise to much speculation and marketing of things believed to make a difference -- such as probiotics which are supposed to enhance positive groups of bacteria within the digestive system. Little is known for certain but it is an additional, important, area to understand for better health and activity.