Fire in the Belly – Shape Matters – Dr Iain Johnston


from Luke’s Journal 2019 | Laughter | Vol. 24 No.2

Editor’s note:  
Asked what sparked his interest in shape, Iain replied:

“Shapes are one lens through which I have tried to analyse physical human and biology.

It has intrigued many, e.g. D’arcy Thompson, Philip Ball, Mandelbrot, Agassiz, Alan Turing, Mike Denton, Brian Goodwin, etc..  I remember my anatomy professor at medical school saying the equal length of our arms is quite curious and somewhat mysterious!

There are other lenses that are also very interesting.   Information technology in bio-informatics (in relation to gene ontology or systems biology e.g. Uri Alon or Denis Noble) is unearthing a profound and beautiful depth to living things that reflect my persisting awe of physiology at work and developmental biology in embryology.

I think as medics and as Christians we could be more aware of the incredible beauty and magnificence of life, more in awe at the physical humans we are asked to look after, and have a sense of the hallowed ground we tread in looking after our patients, fearfully and wonderfully made by our Lord.”


Shape matters. Today, the shape of the cross, whenever we see it, reminds us and everyone who sees it of the most important event in history. The shape carries meaning. It transmits in the blink of an eye what would take a long time to tell in words.

Shape carries meaning in medicine too. We look for and examine shape all the time. The shape of a leg, arm or finger carries great significance. The shape of a clubbed fingernail carries meaning. The moon face carries meaning. The withered leg carries meaning. Shapes tell us things, they carry meaning.

Shapes are also relevant as we zoom in from the largest scale of gross anatomy to the smaller scales of cell shape. Some cells are flat, like skin cells. Skin cells work because they are flat. The flatness creates a barrier, like the tile on the roof of a house protecting the house from sun and moisture. Some cells are cubes, the ideal shape for alignment along a mucous membrane, neatly arrayed, like soldiers on parade. Some cells are hexagonal, ideal for packing tightly, as in the eye lens. The hexagon shape is used around the world by clever honeybees.(1) The bees intuitively “know” this shape is the optimal storage shape versus the efficient use of wax. The hexagon can also cooperatively flex.

Shapes are also vitally important if we zoom in further – from the cell, to inside the cell, to molecules. The shape of the water channel molecule was discovered in 1992 by Peter Agre. His discovery earned him the Nobel Prize in 2003. The shape of the molecule explains how it works. It is shaped like an hourglass, with a narrowing in the central channel to allow only small molecules like H2O to pass. At this crucial narrowing an additional electric field is created by the protein surfaces which prevent even tinier H+ ions passing.

If this seems a little abstract, consider that it is only through knowing about shape that we can understand how we can see.

In two important ways shape is vital to our vision.  Everyone knows that eating carrots is said to be good for your vision. My mum assured me this was in order to encourage me to eat my vegetables. Carrots are a rich source of retinol, which we use to make retinal. It is the changing shape of this molecule that is the central cog on which our vision rests. This molecule is nudged from one isomer to another by a single photon of light. The molecular shape changes and this triggers a domino effect towards sight.

Shape is also crucial to the specialised cell in which this molecule resides – the photoreceptor cells. The two main categories of receptor are defined by their shape, cones and rods, and seen by electron microscopy this is exactly how they appear. The rods are tall and thin, around 30 microns long and 3 microns thick. The cones taper from 1 micron at the tip to 10 microns at the base. The photoreceptor molecules are held at one end of the cell embedded in layer upon tidy layer of membrane, scrupulously folded like ironed linen. These layers allow extreme sensitivity to light, as the huge surface area houses 100,000 light-sensitive protein molecules per cell.

Why does all this detail matter? What is the point of knowing this information if it has little bearing on me, my practice, my patients or as a Christian in my faith?

  • As medical people we are all trained in the basic sciences first. I remember well the emphasis on anatomy and physiology and the terror induced by examinations on these subjects. At the time, I couldn’t see the big picture – where was all this leading? What was the point of knowing in great detail the shape of this bone or that, some tubercle, ridge or protuberance commonly named after a long dead historical figure? Yet each ridge has significance and meaning, which is often linked to function. Our patients present with loss of function and (for the musculoskeletal system) the shape has changed. One of the first things we do in a musculoskeletal examination is compare the right and left shape.
  • For many, understanding the physiology of how the body works provokes a sense of wonder. Being made in the image of God, we are the only living thing that is capable of these thoughts, “Thinking God’s thoughts after him.”(2) For me, there is an eerie awe in peering at an electron photo of a cone cell, knowing that I am walking in the footsteps of the Creator God. For many, a similar feeling is wrought by looking at the Milky Way.  For us as medical people, we have the key to other rooms in creation which may enhance these feeling of awe.

For me, there is an eerie awe in peering at an electron photo of a cone cell, knowing that I am walking in the footsteps of the Creator God. 

  • Thirdly, it is interesting that Jesus restored shape. In his miracle described in Luke 6:6-11, Jesus restored the withered right hand of a man. The healing miracles are the most common type of miracle that Jesus performed.  Many are not even described in the gospel accounts.(3) Why so many? “Miracles are a retelling in small letters of the very same story which is written across the whole world in letters too large for some of us to see.”(4) In other words, Jesus restored the shape of a hand, a leper’s leg, or a guard’s ear to show us that God makes all hands, legs and ears. The link between what we see every day in our patients, in human form, is very close to our Creator God. Each limb and each face is created by God. I believe we can extend this thought to God’s creative intimacy when we see our children’s resemblances to us, indeed, every child’s resemblance to their parents. This resemblance is carried by shapes – a nose, a chin, the eyes.  Each are a subtle, yet undeniable, imprint of shapes – telling a story through time.

Shape matters.


BIO: Dr Iain Johnston, graduated from Edinburgh University, Scotland and completed specialist training in Intensive Care and Anaesthetics in the UK and now in Australia.  Iain works in Intensive Care on the Gold Coast and Tweed Coast with a special interest in acute cardiovascular pathophysiology. He is married to Tarme.  They met over a discussion about Mercy Ships on which Tarme had worked for two years, and Iain subsequently worked in 2012. They now have five children (6 years old and under) – four boys and recently a wee girl.  In his spare time (!) he represents Australia in the World Medical Football Championship.


  1. The honeycomb cells are complex shapes. They are completed at the far end by a partial rhombic dodecahedra! This is geometrically excellent according to mathematical analyses.
  2. Johannes Kepler, astronomer and mathematician (1571-1630).
  3. John 21:25
  4. C.S. Lewis from “God in the Dock” page 13, W. B. Eerdmans Publishing

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