Somewhere in the mountains ©
I praise you because I am fearfully and wonderfully made;
your works are wonderful,
I know that full well.
16 For in him all things were created: things in heaven and on earth, visible and invisible, whether thrones or powers or rulers or authorities; all things have been created through him and for him. 17 He is before all things, and in him all things hold together.
This week has been blessed with intense Bible study, both at cell and Medicine CF. While intellect and the increase of science can make us more wary of committing to a religion or to supernatural belief, I am convinced that there is immense beauty that we can only experience when we truly comprehend God’s creation through mid/high-level study of a particular discipline.
Beauty is a diverse concept. Different people have different notions of beauty, but further to that, it is an extremely diverse idea even in the mind of one individual. For me, I know that music is beautiful, but so is a wonderfully constructed plate of food (some might use the descriptor ‘a symphony of taste’), a mind-blowing photograph or more recently, a taste of human biology.
Embryology features here and there in a Medicine curriculum. It is not primary, but neither is it trivial. My first encounter was nearly a year ago, where in preparation for an interview, I was encouraged to read into an area of science or medicine that piqued my interest. I chose embryology.
To begin with, the development of an early embryo, from a single, fertilised cell, even to a 5-day old embryo (the early blastocyst, for the embryologists out there) is quite mind boggling. Basically what happens is that that single cell (of sperm + egg) begins to undergo a process called ‘cleavage’ - a modified cell division where the cell size decreases with each subsequent division. Then somehow, after a certain point, further divisions yield cells of similar size to their parents, and these organise themselves ever so neatly in a single-layered ball of cells (trophoblast) with another clump of cells inside (embryoblast), adjacent to a fluid-filled cavity (blastocoele). How this even happens is beyond me. Without any control, the cells would simply form a ball (and instead of a foetus, a continually expanding ball), a a bunch of cells floating in the uterus. A significant amount of ‘management’ goes into ensuring that the cells attach to the right places, that they exhibit the right characteristics, and that the even divide properly in the first place. Yes, it is clearly a gene-mediated process. At different stages of development, genes are turned on and off, much like how different settings are assigned at various stages of production in a factory. Yet it remains a wonder how the switches flick in such a precisely-timed symphony, and what has programmed these switches. This is merely the tip of the iceberg, and if you were to imagine how new cells know where to place themselves, say, should the body want to grow a kidney, it is difficult to comprehend. A kidney is made up of multiple components, cell types, and physical layers.
Some suggest that these processes have been achieved through evolution. For instance, taking the above as an example, some individuals may have produced embryos that begin with a 3-part stage (outer layer, inner layer, and fluid-filled cavity). Others may have resulted in different configurations which did not work, and thus failed at reproducing. Since characteristics like such are coded for genetically, the genes that are ‘good at reproducing’ will be passed on to future generations (inherited), and subsequent generations will only get better at this whole reproduction thing.
I actually agree with evolution. Darwin’s theory is a theory, which means that it has been proven many times over, and not yet disproved. And if you ponder the subject, evolution is a terribly elegant mechanism that ensures continuity of only (or mostly) good genes that make their ‘owners’ superior. The problem here is that embryology is such a ridiculously complex process that evolution would require an immense number of tries to make it a success. In evolutionary terms, ‘tries’ represent generations (i.e. a human generation of 20-30 years). I choose to believe that God used evolution as the way to create life as we know it.
But I want to get back to the idea of beauty. In my short course of study thus far, there are two bits of information that once I understood, made me sit back and stare in awe. They gave me the same awe that arises from experiencing a magnificent piece of art (literary, visual, musical) or seeing the beauty in mathematics (an understanding which I can only dream of).
Folding of the Heart Tube
In the adult, the heart comprises of 4 chambers and 4 ‘great’ vessels - big blood vessels that carry blood away from/towards the heart, and later split into smaller vessels. The chambers and vessels are largely separate because they have different functions.
In a developing foetus, the heart begins with a simple tube, surrounded by an empty sac. Over time, constrictions (narrowings) begin to appear, dividing it into 5 different spaces. The tube grows linearly at first. However, the sac eventually gets too small for the tube, which forces the tube to fold.
It is precisely this folding that causes the heart to acquire the artfully-crafted shape it possesses in an adult. If the sac had grown with the foetus and the tube, the heart would remain linear and thus mostly dysfunctional.
Folding of The ‘Tube Heart’ (Source: Langman’s Medical Embryology, 12th Ed)
4 Chambers and 4 Great Vessels of an Adult Heart (Source: Netter’s Atlas of Human Anatomy, 6th Ed)
Closure of Foramen Ovale
In the adult, the left side of the heart contains oxygenated blood (which is carried from the lungs, where blood is bathed in oxygen), while the right side contains deoxygenated blood (after oxygen has been depleted by the rest of the body). Hence the two sides are separate.
In the foetus, oxygen is obtained primarily through the mother, from her blood supply to the placenta. The foetus’ lungs have not developed sufficiently, and it does not have access to the outside environment. Hence, both sides of the heart will contain oxygenated blood. An opening, called the foramen ovale links the left and right upper chambers, allowing blood to mix. After birth, the infant’s lungs begin to function, and this pours oxygenated blood into the left heart. The pressure in the left heart is now higher than that of the right, forcing a septum (a thin wall that was already present, and in fact used in an earlier phase of development) in the left heart against opening. This process occurs spontaneously. With the two chambers now separate, oxygenated and deoxygenated blood cannot mix, ensuring that only oxygen-rich blood is carried to other parts of the body, which used the oxygen.
05 October 2014
Mind the Gene
Identifying the root causes of diseases can be very challenging when symptoms are linked to many factors. Some of the factors are real, and trigger illness, while others only occur at the same time as the illness but have little impact. Telling those factors apart often entails a painstaking process of elimination akin to detective work. Following a two-year investigation, biologists proved at last that the root cause of schizophrenia, bipolar disorder and severe depression lies with a mutation in a gene known as DISC1. They showed that the mutation hindered the formation of synapses (red and green) that allow electrical signals to transit between the tiny gaps linking neurons [brain cells] (shown in blue). Differentiating causation and correlation in mental illnesses poses a particular challenge because genetic and environmental factors both play a role, while many genes are responsible for regulating wiring in the brain.
Written by Tristan Farrow
Laminin is the only protein in the body which actually HOLDS US TOGETHER. Without it, our bodies would fall apart and we would not be able to live. And what shape is it in? A cross.
Sorry to burst your bubble, but laminins don’t actually hold us together as much as fibronectins do. SO fibronectins would be better representations of that function, except they’re boring V-shaped molecules.