Thursday, 18 October 2018
THE pancreas may not be one of the A-listers of the organ world, but 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 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 19th 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).
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.
The pancreas also produces lots of bicarbonate (an alkali) to neutralise all 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 but the pancreas is not finished there.
While its function in digestion relates to what is known as the exocrine system (“exo” means outside and the digestive system is classed as “outside” because that’s where it begins and ends!), 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 when 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 1869 when a chap called Langerhans identified an area of tissues in the pancreas different from the rest. When these areas were (rather cruelly) removed from dogs, the animals went on to develop features of diabetes.
Then it was proved that these “islets of Langerhans” (useful to know for pub quizzes) secreted hormones, the first of which to be discovered was named insulin after the Latin for “islands”.
Now we know the pancreas also produces a hormone called glucagon. These hormones are secreted from the pancreas into the bloodstream and it is here they perform their vital work.
Insulin helps the cells around the body to take up sugar from the bloodstream 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, 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 when it is working well the pancreas 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 probably know the pneumonic GET SMASHED. Each letter represents a potential cause for pancreatitis, the two most common being gallstones and ETOH or excessive alcohol. (The “S” stands for scorpion venom!)
Pancreatitis can range from the mild to the severe and can 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 detection. 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 10 cases may have a genetic element so, if a family member has had pancreatic cancer, younger members may be screened. If you are at all concerned, it is always worth going 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, potentially opening up different possibilities for the treatment and understanding of diabetes and other diseases. For that reason alone, the pancreas deserves a little more of the limelight.
• Next time: The lungs.
16 April 2018
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