Cells can divide

The importance of the fact that cells can divide is something that goes largely unremarked. That they can divide is missed when learning about how they do divide.

We come to a biology class. We learn that there are such things as cells - and how we are composed of cells. We then learn about how they divide. However, the very fact that they divide is highly significant. Yet, we do not ponder the significance of this. We rarely ever stop to consider what this means for our lives.

I will not attempt a list of how cell division is significant. Any list I offer will be incomplete. However, we should always have this in mind.

Is beauty only skin deep?

What makes somebody good-looking?

Is it just a matter of personal taste?

This is a question we rarely ask but our actions are influenced by the answer we omit to seek. An interest in the human body should, at some point, consider what differentiates the quality of one body versus another. But how do we determine quality? What quality or qualities are important?

Instrumentalism

 (The application of a borrowed idea.)

In the philosophy of science, instrumentalism is the view that scientific theories are tools or instruments for predicting and explaining phenomena. Thus, instrumentalism emphasises the practical utility of scientific theories rather than their literal truth. Accordingly, scientific theories do not necessarily provide accurate representations of reality.

This idea does not feature in our day-to-day scientific activities. However, it is an idea about which it is worth being aware. Our descriptions of phenomena are not complete nor entirely accurate. An example of this may be mitosis.

This idea is so central to biology that it seems strange to question its veracity. That cells divide is not open to question. I do question how we describe the process. Biologists are familiar with the four phases of cell division that occur during mitosis:

Prophase - Anaphase - Metaphase - Telophase

(See the Wikipedia entry)

Mitosis is something taught from high school on. It can be demonstrated in laboratory classes using the tips of plant roots. It is easy enough to spot, under the microscope, the phases we are required to find. But are there, in fact, four phases?

Cell division was observed first in the eighteenth century. Not until the late nineteenth century was it described in detail. At that time, only fixed and stained tissue sections were available. Today, it is possible to observe living cells during division. Time-lapse videos of mitosis are available. Sped up, these show a more continuous and seamless process. The four phases we learned - and went on to teach - blend into each other. They are not as distinct, clear-cut stages in the overall process.

I am not suggesting that we get rid of these four phases. The classical four phases serve as signposts. They point to the occurrence of specific intracellular changes. Things about which we should be aware. Recognising mitotic features in cells can be important clinically.

However, we should also be aware that how we learn - and teach - colours our perception. When learning about mitosis, it is easy to think that there are just four distinct phases through which cells pass. This perception is reinforced by viewing microscope slides demonstrating each of these phases. We overlook how the four phases of mitosis are an instrumentalist device - a tool.

That other phases need inclusion emphasises this. For example, Prometaphase, Anaphase A, and Anaphase B are three additional phases suggested. Whether they are widely accepted remains to be seen. The four phases are quick and easy to learn. Thinking in terms of these is deeply entrenched in biological thinking. It is unlikely the four phases will ever be replaced.

Alternatives to homeostasis

Having criticised the concept of homeostasis, I must mention some alternatives. It is not my place to describe each of these or provide a critique of them. For the reader’s benefit, I seek only to list them and give links to where further information may be found.

Allostasis
    Wikipedia entry

Enantiostasis
    Wikipedia entry

Homeorhesis
    Wikipedia entry

Homeodynamics
    The concept of homeodynamics was described by Steven Rose in his book 'Lifelines: Biology, Freedom, Determinism (Penguin 1997). For a review book, see 'Danny Yee's Book Reviews'.

    An alternative use of the term homeodynamics, with some relevance, appears in Terrence Deacon’s ‘Incomplete Nature: How Mind Emerged from Matter’ (WW Norton & Co 2011).

On The Blatantly Obvious

Some things are so obvious it seems ridiculous to mention them. One such thing is our physical symmetry - and our lack of it. Whenever we look into a mirror, that symmetry stares back at us. It is there in plain sight, yet we rarely, if ever, comment upon it. We are symmetrical about a vertical axis, but neither of the other two axes. We have a front and a back, a top and a bottom. Each of these is different. Only our left and right are reflections of each other. We fold neatly in half down the middle. (At least on the outside.)

We are never described as creatures symmetrical about one (vertical) axis and non-symmetrical about the other two. It is taken for granted - it is obvious. As a result, questions fail to be asked about the consequences of this.

There are consequences resulting from the way things are. That includes the way we are. When things are left unremarked because they are ‘obvious’, their consequences are left unexplored.

We need to wonder about those things that are (seemingly) obvious. They can be deceptively so. They need to be explained and yet can so easily go unnoticed. They require hunting out.

I shall be pointing out certain things that are so obvious that it seems ridiculous to mention them - and at the same time, looking for more.

Richard Asher

I recently came across, for the first time, the work of Richard Asher (1912-1969). As well as being known as an eminent endocrinologist and haematologist, he is also known for his work in mental health. In 1951, he described and named Munchausen syndrome - now also called factitious disorder imposed on self.

However, what interested me in him was his writing about medical writing. That he did in a most thought-provoking way. I therefore recommend the following: 

Straight and Crooked Thinking in Medicine

BMJ Aug 21 1954 pp 460-462

[PubMed]

Why Are Medical Journals So Dull? (1958)

BMJ Aug 23 1958 pp 502-503

[PubMed]

RBCs

Nowadays, the abbreviation RBC refers to red blood cells. It is such a familiar abbreviation that one instantly knows its meaning. One does not have to unpack the abbreviation spelling out each word. RBC is almost a word in itself.

However, when I first studied anatomy and physiology (in the mid-1970s), I had a lecturer who did not - or rather would not - refer to red blood cells. He chose instead to refer to them as red blood corpuscles. His reasoning was simple. Red blood corpuscles did not contain nuclei. Lacking nuclei, they did not qualify as cells in the true sense.

The word corpuscle was more prevalent then. My lecturer was not coining terms. He was being very particular about his choice of words. That was because of what the words implied.

Red blood corpuscles are the end products of cell lines that once contained nuclei and were previously able to divide. Now, they have become specialised as oxygen transport vehicles. In so doing, they have lost their nuclei and their ability to divide. Accordingly, they have a limited lifespan of only a few months.

Almost every time I hear the phrase red blood cell, I think of that lecturer over fifty years ago and wonder why that bit of reasoning is no longer in fashion. Corpuscle means little body. Being called little bodies differentiates these blood-born objects from anything else of similar size. Red blood corpuscles are the only things in the body to which the word corpuscle became associated. Using that term recognises them as not being like other ('proper') cells. This gives RBCs their own special status.