What is physiology?
I am a physiologist. This is my outing in three parts. First, I will show that you cannot get easily an answer to What is physiology? In a second post, an answer is coming from the editorial of the current issue of Acta Physiologica, which aims at a harmonization between European physiology curricula. Finally, I will identify overarching concepts that define physiology. These concepts date back to the nineteenth centure but are still valid today.
Actually, I am a physicist—by training. I am a physiologist by heart.
Beginning with this posts, I will explain what physiology is. This and the subsequent posts are based on the first lecture that will be given in a new course called "Dynamical Diseases", which I am developing right now for the winter semester 2010 at the TU Berlin. I will start the course with the question:
What is physiology?
Of course I have a good idea what physiology is and I had it before I decided to develop this course. But once you teach, you need a thorough understanding of what you are talking about, even about short remarks within the introductory part of the first lecture. You never know what students might ask.
So I began a journey to better understand what others think physiology is.
From the meaning of the word physiology in ancient Greek we deduce that it is the study of nature. But so is physics. And clearly physics and physiology are different disciplines.
Physiology, Wikipedia (note that this post refers to the version in August)
Here is a simple answer from Wikipedia [1]:
Physiology is the science of the functioning of living systems.
As such it is a branch of biology. Biology includes also other things of living systems like their structure, growth, origin, evolution, distribution, and taxonomy. Yet, if you read on on Wikipedia, you are not learning much more than this, except for some—incomplete—history of physiology.
(Of course, I should complete the Wikipedia entry and not complain about it. I will do so, but one thing is writing for Wikipedia, another is writing my blog post. The latter goes first because I have to prepare my classes.)
Collage of Nobel Laureates in Physiology or Medicine. From NobelPize.org
Physiology is a major discipline in science. There is even a Nobel Prize in Physiology. Actually it is the Nobel Prize in Physiology or Medicine. And, of course, there is one in Physics. And in Chemistry, Literature, Economic Sciences, and Peace.
Well, I checked all these disciplines in Wikipedia and guess what, two articles have issues. Peace and Physiology. Peace? Ok, forget about it. But physiology? Why can't we have a decent Wikipedia article on physiology (as of August 2010)?
I looked into the Brockhaus, a German-language encyclopedia. Only a sixth part of a page is devoted to Physiology. I did not get more information than is given in the first sentence in Wikipedia citet above. Then I looked for the Physics entry: over 6 pages.
Really? There is 36 times more to say about physics than about physiology? I don't think so. Now I was really curious. There is the Encyclopædia Britannica. My favorite encyclopedia. Unfortunately, it is located only in our main library of the TU Berlin. I had to walk there 15min one way, but it was worth it. (Now I wonder whether I can effort the monthly membership of €8.99 to get the online version?)
I only checked the Micropædia, i.e., the short (fewer than 750 words) articles within the Britannica. I looked for physiology and physics. This time physiology clearly won by the amount of words. More important, I got confirmed what my intuition was in the first place. Physiological processes are dynamic processes that aim at preserving a constant physical and chemical internal environment. This is an important point. Physiology is much about regulation, that is, closed-loop control systems.
This matched what I learned in 1992 when I bought my first book on Physiology. Actually my first book that dealt with life sciences. It was called "Physiologie" and was edited by Peter
Deetjen and Erwin-Josef Speckmann. The zeroth chapter was written by the editors, and introduced physiology as a science of biological regulation. A perfect introduction, if you ask me. Unfortunately somewhere on its way to the fourth edition, this introduction got exchanged for a rather meaningless chapter
"Physiology – ein heißes Thema" (Physiology—a hot topic). Its is all bla bla bla now. Nice to read, but no information. Sorry to say this.
Before I can come back to physiology as a science of biological regulation (third post), in my next post, we will learn about current tendencies to harmonize the physiology curriculum at European universities. There, we will take a closer look at what major body systems actually need to be self-regulated.
For now, I invite you to comment here on what you think physiology is.
[read on]
Hi Marcus,
I was puzzled as to why you think Physics and Physiology should be in proportion.
Physics is all-encompassing in its own right, but is also a sub-discipline of all other physical sciences, for example, mechanics, but more to the point here, biological mechanics. It goes from the small particle physics, to the large cosmological physics. This is a pretty big field.
Physiology on the other hand ranges from the small, say multiple cellular activity, to the large, say biological mechanics again, which on earth is no larger a scale than the largest animals. Physiology is also only about animal life (is that right? what about plants, single cell organisms?) whereas physics can be about life and the inanimate.
Hi Ron,
for one thing, are you not puzzled by the fact that there is hardly any information in Wikipedia or the Brockhaus on physiology?
Nonetheless, there is probably not an obvious proportion that should be reached. What should be the general knowledge people have in Physics and Physiology?
And once we talk about how many books are published in either subject, I think this is totally up to the public interest, number of students a.s.o and this number does not reflect anything but commercial interest and teaching needs a.s.o. Fine.
So back to an encyclopedia with limited space (which is not really true for Wikipedia).
This is what I like about the Encyclopædia Britannica: its Micropædia has short articles, usually fewer than 750 words each, while in the Macropædia is more space for detailed information.
Any encyclopedia , Wikipedia included, should give the essence of a subject first and very concisely. For Physics you need not many words: "physics is concerned with [...] nature, covering [...] objects under the action of [...] forces and the nature [...] of gravitational, electromagnetic, and nuclear force fields. The goal of physics is to formulate [...] principles that bring together and explain all [...] phenomena." (from Encyclopædia Britannica, meanwhile I have online access).
Physiology can be almost as concisely be described, but what is missing in Wikipedia or the Brockhaus is naming the major body systems (see next post).
It is a bit like forgetting in the above statement to mention gravitational, electromagnetic, and nuclear forces and merely saying Physics is about objects under the action of given forces. If you would know the latter, but would not be able to name the forces, it is not really working knowledge you can build on, is it?
In fact, to defend the honor of Wikipedia (I am a big fan and actively contribute to it, whenever I can, but I am also very careful with the found information), you find the major body systems one click away, in the article "Human Physiology". And maybe this really belongs there (I would questions this), because there is also plant physiology and (single) cell physiology, since you asked.
To summarize, I would like to see in the canon of education some basic understanding how we pee and why the apple falls down. My guess is, that many people will think of gravitation and even curvature of space(time) but whether the urinary system pops into mind, I don't know. I could be wrong here, after all, I am a physicist by training ....
First off, my answer to your question:
Off the top of my head, I think physiology is the science of how organisms function.
You are right in stating that the wikipedia entry on "physiology" is strangly deficient, given the importance of that field. But then, there is also a much more comprehensive entry on "Human physiology" ...
http://en.wikipedia.org/wiki/Human_physiology
... which then branches off into all the related sub-fields. I'd say that this goes into a satisfactory level of depth, keeping in mind that wikipedia is an encyclopedia ... no less, no more.
As an aside, I did a google search on "physiology". Google came up with 29,700,000 hits. When I tried the same on "mechanical engineering" (my university major), I got only 22,000,000 hits. What a mortifying experience.
The first book on physiology that I purchased was "DTV Atlas der Physiologie". How do you rate that book? I don't know whether it has ben updated since I bought it in the late 1980s.
Michael,
your are right both with your top of my head definition and the hint to the other Wikipedia article on Human Physiology. That is what my next post is about (see also the answer to Ron).
I don't know the "DTV Atlas der Physiologie" but some old books are surprisingly good.
What is still missing, once we have your top of my head definition plus the major body systems (see Human Physiology in Wiki) is the aspect of control.
Physiology is the science of biological control. That dates back to Claude Bernard, James Clerk Maxwell, Emil du Bois Reymond, and others. This aspect went through a (partial at least) eclipse.
But now I am ahead of my postings ...
Cheers
Markus
I am an anesthesiologist and have special interest in physiology and the seamless universe.
I am in the process of sorting out a book (PHYSIOLOGICAL BASIS OF ACUTE CARE) for young doctors managing acutely ill patients in the front line where this question -WHAT IS PHYSIOLOGY is my opening chapter. Although this may have a slant towards providers involved in the management of the acutely ill patient, it might be useful to share my thoughts on the subject with you especially if you are teaching in the medical curriculum. I am enclosing that chapter below:
WHAT IS PHYSIOLOGY
Physiology is the study of LIFE and how the body organizes itself to sustain this through the functions of the various tissues and organs in the human body. All these work together to allow the cells in our body to enjoy an environment not too different from the primordial environment (the sea) that all single cell organism is said to have hailed from. The single cell organism for example, needs oxygen from its environment and this simply diffuses into the cell from the environment and it produces carbon dioxide which again moves into the environment. In a complex organism like the human, this simple movement of gases or other needs across the cellular membrane into or from the environment is not possible. There is organization of functions in the various organs or systems of the body to try to bring the internal environment around all cells to that resembling the primordial environment.
This organization is at a level where the control is tight to keep the environment as constant as possible. Most systems in the body have an arrangement where changes are sensed and changes noted. These are sorted out in a control system which uses a negative feedback mechanism to bring about compensatory changes through an “effector” system. If this feedback mechanism is exhausted, de-compensation occurs and the organ or organism deteriorates in function threatening the life of the organ or organism.
All organisms have simple needs to live - oxygen, glucose (or other energy sources) for producing energy, proteins for structural needs and different minerals and other elements for special functional needs. Oxygen and energy production interface at the cellular level. Glucose undergoes aerobic metabolism (combustion) under normal circumstances and in the process of production of ATP produces electrons which has to be taken up by oxygen where carbon dioxide and water are produced. In the absence of oxygen, glucose undergoes anaerobic metabolism but this cannot be carried out indefinitely because acids are produced and the environment changes dramatically from normal.
For most acutely ill patients, the most important need is their need for oxygen which must be delivered in adequate amounts in order to ward off the threat of death. Life produces waste products which have to be removed from the cells/tissues or organs and these are removed in a methodically manner to keep the tissue milieu constant. Waste products that can undermine the life process and threaten the internal environment include carbon dioxide, fixed acids, water and even heat load and all these have to be systematically removed mainly by the cardiovascular system from the environment of the cell and removed from the body by the respiratory and renal system and the skin respectively.
thanks for sharing this. I read it with interest.
Actually the easiest definition for me is the study of nature.However,I like the more in depth meaning. The branch of biology that deals with the normal functions of living organisms and their parts.