Essence of Many Diseases: Homeostasis

In his book Wisdom of the Body, Walter Cannon, an American physiologist, discussed an importance of phenomenon known as homeostasis. He said in one part of this book, "The coordinated physiological processes which maintain most of the steady states in the organism are so complex and so peculiar to living things - involving, as they may, the brain and nerves, the heart, lungs, kidneys and spleen, all working cooperatively - that I have suggested a special designation for these states, homeostasis [italicizing done by the source, not by me]."¹

This term, homeostasis, may not be familiar to everyone. From the surface, it sounds like one of those scientific jargons that can be only found among the complex details in biology textbooks. In contrary, however, in my copy of Human Anatomy & Physiology, Fifth Edition, by Elaine N. Marieb, page 10 discusses homeostasis. There are total of approximately 1,200 pages in the book, so the author's intention to explain this term so early in the book is not a coincidence; instead, she did this because she knew how important this term is.

Basically, the best way that I think of homeostasis is like a "switch." If the amount of certain substance increases, then the body turns "off" the switch for making that substance and turns "on" another switch that can help to reduce the level of that substance back to the normal range. The most common example of this involves pancreas's alpha and beta cells for production of glucagons and insulin, respectively. This control mechanism is familiar to people today because of the common occurrence of diabetes.

But, this application is only a small part of the fascinating abilities due to homeostasis.

In our body, lung is involved in carbonic-acid-bicarbonate buffer system, which is used to maintain constant pH of the blood. The equation for this buffer system can be found here, and preserving constant level of pH is probably one of the most crucial mechanisms for organisms. Failing to do this will result in acidosis, which is a decrease in blood pH due to increased amount of acid in the blood, or alkalosis, which is an increase in blood pH due to increased amount of base in the blood. A normal pH for human is about 7.40.²

So, how is the homeostasis really related to many diseases? The "idea" is simple: failure of homeostasis. Usually, when someone becomes ill, it is due to various factors, and is not always easy to pinpoint exactly what caused the disease. But, one thing that can be explained in many, not all, cases is on what did not go right, or which part of the body failed to continue its homeostasis.

A bit more medical example to elaborate this is osteomalacia. Osteomalacia is "caused by insufficient calcium in the diet or vitamin D deficiency."³ So, how is this disease can be used to explain the homeostasis? Well, here is one possible way: relation between parathyroid hormone and calcitonin. Parathyroid hormone synthesizes vitamin D and increases calcium concentration in the blood system. On the other hand, calcitonin's job is to reduce the calcium concentration. Let's hypothetically say that a patient decided to take a medication that worked as an inhibitor for parathyroid hormone. If this happens and the body only has calcitonin working, the body will not be able to make any calcium or vitamin D, resulting in deficiency for both of them. Of course, the details on as to if such case can really lead to osteomalacia is not clear since as I said before, the exact causes of diseases usually vary. But, what is clear is on what can happen if the body fails to maintain the delicate homeostasis of calcium. There can be other side effects as well since calcium is used in nervous system, as explained in my article about Alzheimer's Disease.

Bottom Line

As you can see, homeostasis is crucial, and the best way to maintain it in your body is to simply do not "overdo it." This does not mean that you can't go on your Tuesday wing nights with your buddies or indulge yourself with your favorite pumpkin pie every now and then. No, the real point is that you should do your best to stay within the limits. Our body, as Dr. Walter Cannon explained, is truly amazing and can adapt to different challenges that it faces. But, we have to remember that it is much easier for body to prevent damages than to fix damages. So, stay healthy and keep up that homeostasis!

Works Cited

¹ PanArchy, "Walter Bradford Cannon: Homeostasis (1932)," Accessed July 9, 2010

² James L. Lewis, III, M.D., "Introduction: Acid-Base Balance: Merck Manual Home Edition," Merck, July 2008, Accessed July 9, 2010, ³ Elaine N. Marieb, Human Anatomy & Physiology (San Francisco: Benjamin Cummings, 200