The Pancreas

While the pancreas may not be one of the A-listers or showstoppers of the organ world (if there is such a thing), it is as important as any other cog in the system. For a long time, perhaps owing to its position behind the stomach, its true function was completely unknown. It is curious in appearance, shaped a bit like a leaf and rubbery in texture (apparently). This gave rise to a certain vagueness in its naming – it means ‘all flesh’ in Greek. Until the late nineteenth century, many thought its only function was as a shock absorber in the upper abdomen just below the ribs and the sternum.

 

 

The discovery of a sneaky duct that connects it with the first part of the small intestine was the first clue that it might have a deeper role. It was then discovered that the pancreas secretes a rich cocktail of juice and enzymes through this duct and into the intestine in order to help with our digestion. Specifically it helps in breaking down fats (with an enzyme called lipase), starches (with amylase) and proteins (with various different proteases). Basically, anything with ‘ase’ at the end generally means it is an enzyme of some form or other.

This is important because, without the ability to break these dietary components into smaller building blocks, we would not be able to absorb them from the intestines into our bloodstream. In addition, the pancreas produces lots of bicarbonate (an alkali) to neutralise all of the acids secreted in the stomach so that once your food gets into your intestine, it is at optimal pH for absorption.

That role alone is extremely useful you might say, but the pancreas is not finished there. While its function in digestion relates to what is known as the exocrine system (essentially ‘exo’ means outside and the digestive system is classed as ‘outside’ because it begins and ends outside!) the pancreas has a vital endocrine role. Endocrine relates to the travels of hormones throughout the closed circulatory system, i.e. the blood.

In those years where scientists considered the pancreas to be nothing more than a glorified cushion, hormones controlling the body’s sugar levels were thought to be pumped into the circulation from the brain. This idea persisted until a chap called Langerhans identified in 1869 an area of tissues in the pancreas different from the rest. When these areas were (rather cruelly) removed under anaesthetic from dogs, the animals went on to develop features of diabetes.

Through various means subsequent to this, it was proved that these ‘islets of Langerhans’ (useful to know for pub quizzes) secreted hormones, the first of which discovered was named insulin after the Latin term for ‘islands’. We now know that the pancreas also produces a second hormone called glucagon as well. As part of the endocrine system, these hormones are secreted from the pancreas into the bloodstream and it is here that they perform their vital work.

Insulin helps the cells around the body to take up sugar from the blood stream to use as fuel and also helps to store it in the liver. Glucagon performs the opposite role, mobilising energy stores in the liver and fatty tissue for those days when we’ve not had time for lunch or have decided to run a marathon.

In this way, to use a rather crude comparison, the pancreas is a bit like the national grid. When it receives certain signals that more energy than usual might be required, like going for a long run (just as TV coverage of a royal wedding, for example, might cause a surge in electricity uptake, to keep the national grid analogy alive), it prepares by secreting more glucagon to draw from the reserve of energy we keep stored in our livers and fatty tissue. If, on the other hand, we are providing more energy than we need by eating lots of sugar, the body switches to insulin to use up the sugar being eaten and store any spare energy left over. 

So evidently the pancreas when it is working well is extremely important. When it is not, diabetes can result. But what else might go wrong?

Sometimes, the pancreas can become inflamed and this is known as pancreatitis. Every medical student will most likely know (or at least have heard of) the pneumonic GET SMASHED. Each letter represents a potential cause for pancreatitis, the two most common being Gallstones and ETOH or Excessive Alcohol. ‘S’ stands for Scorpion venom and, as there are not many scorpions running around Henley, I’ll not dwell on that too much.

Pancreatitis can range from the mild to the severe and can even be life threatening. Symptoms include severe upper abdominal pain going through to the back, nausea and vomiting. You may also sometimes get a fever and also diarrhoea. It often results in a stay in hospital where you can receive pain relief, fluids and oxygen if needed.

The other main condition affecting the pancreas is cancer. Pancreatic cancer is the UK’s 11th most common cancer and tends to affect those in older age groups more. Around 9,600 people in the UK develop pancreatic cancer each year.

The big issue with pancreatic cancer that gives it a high mortality rate is the difficulty in its detection. This means that it is often picked up only at later stages. Researchers are always looking for effective tests that might be used as a good screening tool, but as yet none has been found. The symptoms are often very vague but include…

-Weight loss

-Dull, boring pain or fullness in the upper abdomen which can go through to the back as well

-Jaundice, often without pain or any other symptoms (this occurs because of the pancreas’s proximity to the bile duct which, if pressed on, causes a back-up of the pigment bilirubin in the blood.)

One in ten cases may have a genetic element so, if a family member has had pancreatic cancer younger members may sometimes be screened.

If you are at all concerned about this, it is of course always worth coming to see your GP for a check.

As always, there is always more to learn. Even now, research is being done into other hormones produced by the pancreas which may perform roles as yet unknown, thereby, in the future, potentially opening up different possibilities for the treatment and understanding of various diseases, including diabetes. For that reason alone, I think the pancreas deserves a little more time in the limelight.

 

 

 

 

 

The Brain

While we know more than we ever have, there is still a lot to learn meaning that, in an ironic sense, the brain is still something we can’t fully get our head around.

Someone once said that if the human brain were so simple that we could understand it then we would be so simple that we couldn’t. I would have to agree. The brain is our vastly complicated seat of consciousness and individuality, controlling most functions of the body, some of which we are aware of and some of which are on a more subconscious level.

If one were to zoom in to see it under a microscope, one would find literally billions of nerve cells, or neurons, forming a continuous interconnected network signalling to each other using electrical pulses and chemical transfers. There are around 86 billion of these neurons in the adult brain, meaning that if you were to pick an area of the brain the size of a small grain of sand you might find as many as 100,000 neurons in just that one area. What’s more, each one connects to around 1,000 others via connections known as synapses.

As we zoom out again, we see that the brain has a wrinkled surface that, if stretched out flat, would cover the area of four A4 sheets of paper. It is cushioned and bathed by a viscous layer of cerebrospinal fluid that, as the name suggests, runs all the way down around the spine as well.  Weighing in at around 2% of our body weight, our brains manage around 98% of human function, which is a pretty good return. It follows therefore that it needs a fairly good power supply and, indeed, it has an important network of blood vessels that supply it with oxygenated blood and nutrients – it uses around 20% of the body’s energy supplies.

With such a complex make-up and such a plethora of responsibilities, it is no wonder that it is regarded with such intense interest and yet is still relatively poorly understood compared with other organs of the body. As with much scientific endeavour, much progress has been made in its understanding over the last century.

Take the frontal lobe for example. As part of the quest to understand the brain in more detail, scientists identify areas in accordance with their perceived function. The frontal lobe is thought to be involved in executive function such as judgement, decision-making, planning and control of behaviour – functions that became clear following an accident involving a railway worker named Phineas Gage in which, rather unfortunately, he received a metal pole through his forehead. Though he survived this ordeal, the once calm and understated worker famously showed a marked change in personality towards aggression and surliness.

Had the pole gone through his occipital lobe, he might have had trouble with his vision and, if it had pierced the temporal lobe, he would potentially have had trouble processing sound, using his memory and producing speech.

The point is that certain areas of the brain are involved in particular tasks. This can become apparent when someone has a stroke. Most strokes happen when blood supply to an area of brain tissue is interrupted.  The result can be, for example, loss of motor function in one side of the body. If there is a problem in one half of the brain, then the problem (when talking about motor function – i.e. moving an arm) manifests in the other side of the body. This is because nerve fibres from each side of the brain cross over at a certain point before descending the spine to the rest of the body.

We know that the brain performs so many functions. It allows us to move, to smell, to hear and to sense temperature. It also enables us to think. While this complexity is admirable, when it goes wrong the consequences can often be very distressing. Infection, head injury and cardiovascular disease all affect the brain’s health, as well as conditions such as Parkinson’s disease which affects the production of dopamine, (normally used to regulate our movement) and resulting in involuntary shaking, slow movement and stiff muscles.

Most significant of all, as our population grows older, dementia is becoming the largest cause of mortality in the UK and all over the developed world. Research is ongoing and we still have a long way to go both in understanding the processes involved and in treating the effects. It should be mentioned that dementia is not a single disease, rather a term to describe the symptoms that occur when there is a decline in brain function.

Alzheimer’s is the biggest cause of dementia. Though not fully understood, it is believed to be related firstly to the build-up of amyloid plaques and secondly to neurofibrillary tangles made up of proteins called TAU proteins. As more of these build up, the ability of the neurons in the brain to transmit information gradually diminishes. Research is currently focusing on the processes involved in the development of these two features. Just as importantly, the search is on for biomarkers (markers that we can sample in the blood or spinal fluid) that might give us an idea of whether someone might be developing a dementing condition, giving greater opportunity to take early steps to manage the condition and also to research disease progression over longer periods of time. Although it can be difficult to face, and often slow to present, if you have any concerns about memory, it is important to see your GP as there is often support available and it may also be the result of more benign and treatable conditions (for example low vitamin B12 levels or underlying infection).

When concentrating on the more physical effects of the brain, it is sometimes easy to overlook the deeper thought processes that are involved in our mental health. Much of our individuality comes through the environment in which we grow up. In the same way that we form new connections and synapses in our brains through repetition as we learn an instrument or practise our times-tables for example, it is thought that personality traits develop to some extent in the same way. For untold reasons, however, our minds can be fragile and depression and anxiety can be extremely damaging. Often there are so many different factors, both social and physical, that make such emotional issues difficult not only to treat but also to recognise. Chemical imbalance plays its part, for example in relation to levels of serotonin in the brain, and in such cases there can be a role for medication. More recently, there has been a push for increased awareness of mental health conditions in an attempt to remove any stigma attached to something that can cause a lot of problems if left unaddressed.

How do we look after our brains? Staying happy is a good start and there is plenty of support available for people for whom this is not the case. Keeping your mind busy helps to maintain your ‘neural plasticity’ – it ensures you are creating new synapses by learning new things. Maintaining healthy social networks is equally as important.

Regular exercise is vital for brain health as it increases the blood supply to the neurons, reduces blood pressure, helps blood sugar balance, improves cholesterol and reduces mental stress.

Getting enough sleep each night is important (8 hours being the aim).

Your diet can also give you benefits. Anything rich in omega 3 such as oily fish is useful and a ‘Mediterranean-style’ diet is a good start. Blueberries are rich in anti-oxidants, thought potentially to reduce inflammation involved in plaque formation in the brain, and dark leafy greens, such as kale and spinach, will give you good sources of vitamins C and E and folates – all thought potentially to reduce the risk of Alzheimer’s.

There is some evidence to suggest that certain people may benefit from medications like statins and aspirin but it’s always a good idea to come in to discuss any medication with your GP or pharmacist. And don’t forget not to smoke or drink too much alcohol.

While we know more than we ever have, there is still a lot to learn meaning that, in an ironic sense, the brain is still something we can’t fully get our head around.