A Rule of Three

 Anatomy has a lot in common with geography. The phrase ‘topographical anatomy’ is sometimes used to refer to the study of the location of different body structures. Whether ‘study’ is the correct word is a moot point. Learning where everything is situated is not so much ‘study’ as ‘memorisation’. A lot of anatomical study involves rote learning. This is onerous, tedious, and [add your own derogatory term(s) here if you find this process irksome]. It is not learning in the true sense. It is 'cramming' for an exam.

Aides to learning (and memorising) are to be welcomed. There are many mnemonics one may use. (Some of them are clean! The clean mnemonic for the 12 pairs of cranial nerves I do not remember, but the more risqué one I had memorised on only the second hearing!)

There is a more thoughtful approach. Where possible, look for anatomical principles. Look out for commonalities and patterns.

The first of these is ‘the rule of three’. Anatomical structures do not consist of a single cell type. They are typically made of layers of cells and extracellular material. These layers are often continuous with each other and are hard to differentiate. Sharp distinctions between layers are not always obvious. However, that has not stopped anatomists from giving them specific names.

As a rule of thumb, start with the assumption that there are three named layers. Look out for these and memorise them that way. What applies to one structure often applies to another. Once a principle has been learned, it is applicable elsewhere. Sometimes the same or a similar word is used.

Helpfully, the outermost layer of a structure is usually a connective tissue capsule that envelops an organ or loose connective tissue that forms a kind of ‘packing’ (such as around blood vessels). If there should be more than three named layers, it is often because a ‘parent’ layer has been subdivided. Usually, this is the middle or inner layer. Realising this helps.

A question arises.

Is the ‘rule of three’ a genuine anatomical arrangement, or is it a reflection of the mentality of the anatomists who originally named these layers? That is something else to consider. Being unconvinced about what we have to learn helps us remember it!

Newton saw seven colours in the rainbow. (From which we get the mnemonic Richard Of York Gave Battle In Vain.) But the seven-colour idea was more in keeping with a Renaissance tradition than observation. Did he really see seven colours? And do we when we see a rainbow or light shone through a prism? Or are we simply following what we have been taught?

The cell as a processor 2

 

[Visual thinking - something to look at and think about.]
[See also: The cell as a processor 1]

The cell as a processor 1

 

[Visual thinking - something to look at and think about.]
[See also: The cell as a processor 2]

Comment

I have tagged a few posts with the label 'Comment'. I have not said what I consider a comment to be in the context of this blog. Here, I shall set that right.

A 'Comment' is something I happen to have thought. I do not claim any rigorous academic basis for these comments. Thus, a post labelled 'Comment' can be almost anything. It may be an opinion, idea, thought, musing etc. It may come from left (or right) field. It is simply something 'put out there'. It is for the reader's consideration. It is something to think about. Accordingly, it is something the reader may choose to ignore.

Life bearing upon life

Now in retirement, much of how I look at the world is informed by insights and experiences gained over nearly 70 years of life. This leads me to wonder what insights and experiences might be available were human life span two or three times what it is now.

At the equivalent phase in such a life, I would be looking back with what had been gained from having lived nearly 200 years - not a mere 70! I could be looking at things today, remembering lessons learnt from a period beginning in the early Victorian era. It is not enough to know things through history books. What insights might I have now, had I had intimate experience of that time and those periods since?

Our lives last, on average, two or three times longer than our forebears a millennium or two ago. With much shorter lives, they must have had much less personal experience upon which to draw. (Presumably, they were able to draw upon other resources.)

It is our biology that gives us lives of a certain longevity. Subsequently, that longevity influences how much is available as we negotiate that very life.

Plaster of Paris meal

Somewhere in Britain, during the Second World War, a hospital X-ray department constructed a makeshift darkroom for processing its films. In those days, X-ray images were made on film, not digitally. These images required 'development'. That was achieved by passing an exposed film through a series of chemical baths. X-ray film was also sensitive to light which ruins the image by 'fogging'. Apart from a very dim red light to which the film was insensitive, darkrooms had to be light-proof. Unfortunately, the walls of the new darkroom had cracks in them. These were letting in light and fogging the films.

Somebody suggested filling the gaps with a mixture of Plaster of Paris and barium sulphate. A slurry of this mixture could be applied to the walls, allowed to dry and the gaps sealed. Furthermore, in those days, both Plaster of Paris and barium sulphate were readily available in hospitals. No extra expense was necessary.

Plaster of Paris was used for the plaster casts that supported broken bones. There was plenty of this available in the fracture clinic. Barium sulphate was used as a contrast agent for barium meals and enemas. The X-ray department already had plenty of that in store. The mixture was made but left unattended. Before it could be used, somebody mistook it for a standard barium meal mixture. Outwardly, nothing indicated the inclusion of Plaster of Paris. Typically, batches of barium meal mixture would be made up before use. This appeared to be part of such a batch.

Thus, it was given to a patient who duly drank it. By the time the mistake was realised, nothing could be done. Now inside the patient’s gut, the fear was that the Plaster of Paris would set and cause a blockage. This could prove fatal. At best, the removal of a section of the patient's intestine might be necessary. Even today this is radical surgery. In the 1940s, it was particularly hazardous.

Initially, the patient experienced no ill effects. All that could be done, was wait. Over several days, the patient’s abdomen was X-rayed to check on progress. Surprisingly, the Plaster of Paris did not set as feared - at least not into one single, gut-blocking mass. The mixture dissipated and passed through without harm. In this, the strength of the gut’s peristaltic action seems to have played an important role. It fragmented the swallowed bolus into small, transportable pieces that passed out naturally.

Everybody was relieved. Whether this included the patient is a moot point. The patient may have been left quite unaware of the mistake. In those days, patients were told much less about their conditions than they are today. That raises an interesting ethical question. If this happened today, should the patient be informed immediately of the mistake? That might cause undue distress and worry (and a lawsuit). Or, should we wait and, if no harm is done, simply let the matter rest?

I'll leave this up to the reader to decide. 

Metabiology

I first encountered the word ‘metabiology’ in J.O. Wisdom’s review* of J.H. Woodger’s book ‘Biology and Language: An Introduction to the Methodology of the Biological Sciences including Medicine’ (Cambridge University Press, 1952).

It was as a result of an online search. The story of how metaphysics got its name is well known. As organised by his editor, Andronicus of Rhodes, Aristotle’s treatises on (what we now call) metaphysics were placed after those on physics. The prefix, ‘meta’ means ‘beyond,’ ‘after,’ ‘along with,’ or ‘beside.’

I wondered whether the prefix ‘meta’ had been used with ‘biology’; I wondered too what those topics ‘beyond,’ ‘after,’ ‘along with,’ or ‘beside’ might be.

I have found that ‘metabiology’ is a term used to describe an interdisciplinary field that combines biology with concepts from other scientific disciplines. These include computer science, physics, and mathematics in studying complex biological systems. Here, the focus is on the fundamental principles that underpin biological processes. As such, its focus ranges from the molecular level to ecosystems.

That approach opens up a range of new questions. These are practical questions. They are in keeping with the current biological style. However, I had hoped to find metabiology addressing questions of a more philosophical nature. I still think (hope) that the word 'metabiology' can be used to encompass this kind of thinking. After all, it is something ‘beyond,’ ‘after,’ ‘along with,’ or ‘beside.’

* In: The British Journal for the Philosophy of Science, 4 (16): 339-344.