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The digestion process

The digestion process

What happens when we eat?

It’s a process called Digestion, basically it is the bodies process of in-taking and breaking down of all the food and drink we consume on a daily basis, although digestion may take longer than we take to eat/drink it! Absorbing and breaking it all down into smaller molecules like carbohydrates, proteins, fats, and vitamins, to used or excreted by the body inline in what we need and what its need for, for example energy, growth, repair etc.

As Roberts states ‘the digestive system enables us to take in food, break it down physically and chemically and extracts useful nutrients whilst excreting any waste not needed’ (Roberts, 2010, P.192).

It all begins when few eat or drink as food enters our mouth’s. Our teeth, saliva and tongue all work together breaking down food into small moist ball’s, masticating (chewing) to break the food down initially into a manageable size, which we can then easily swallow and it disappears into our bodies where more magic takes place.

To begin with our teeth grind each mouthful of food then the major salivary glands kick in (Parotid, submandibular and sublingual) secreting saliva through ducts into our mouth’s. Our saliva is very powerful, containing digestive enzymes (known as amylase) which chemically help breaking down the food we have placed into our mouth’s. Whilst the tongue controls the food and pushes up against the hard palate in the mouth as you swallow, it also contains taste buds which allow you to distinguish between potentially harmful food and good food (Rowett, 1959). During the process of swallowing, the soft palate seals off the airway allowing the muscular tube of the pharynx to contract by pushing the moist ball of food down the oesophagus and through to the stomach this is also known as peristalsis (a wave-like contraction). Pepsin an enzyme which helps break down proteins exists in the stomach and is one of the many enzymes required for digestion helping with reducing the size of food so it can be absorbed better.

Hydrochloric acid also exists in the stomach to kill off any harmful bacteria. Whilst the stomach has a smooth muscle where functions of the gut, blood vessels and respiratory tract are carried out involuntarily at a subconscious level, it also has a thick layered wall muscle which contracts to churn up food (Baggeley, 2001). Once food has been broken down into smaller particles it is then secreted into the first part of the small intestine, the duodenum. Roberts writes about how bile is secreted into the duodenum from the stomach whilst Open Study College comments on how it is the liver which produces and secretes bile into the duodenum (Roberts, 2010, P.201), mucous aids with the pushing down of food along with the peristalsis process as it travels through into the jejunum and ileum where digestion continues.

The jejunum is part of the small intestine where food passes through quite quickly, the ileum which lies in the suprapubic area of the abdomen is also part of the small intestine and absorbs mainly vitamin B12, bile salts and any other nutrients which have not been absorbed by the jejunum. Whatever is left is then passed through into the caecum, the first part of the large intestine lying in the right iliac fossa of the abdomen (Roberts, 2010). The large intestine is where the final stage of the digestion process occurs before waste is eliminated into the rectum. It is in the large intestine where vitamins and minerals are again absorbed, water is absorbed in the colon so that the gut contents become more solid. Faeces are stored in the rectum which is then secreted through the anal canal.

Diverticular disease is when inflammation occurs in the colon and the intestinal wall, causing pain and disturbance of bowel function. Small pouches of diverticula develop in the lining of the intestine, if faeces are low in fibre, the force of contractions increases. This peristalsis action puts pressure on the walls of the colon and as a result diverticula forms. The intestinal lining is put through weak points in the muscle of the walls causing faeces to get trapped in the pouches and bacteria to grow (Baggeley, 2001).

The liver plays a huge role in the digestion process, although it has been speculated bile is produced in the stomach, it is in fact the liver which produces bile which is then stored in the gallbladder and helps to digest fats (Baggeley, 2001, P.229).

The portal vein is where nutrients pass from the gut through to the liver, blood is filtered of all it toxins from the small intestine in the liver along with harmful substances such as drugs and alcohol. Glycogen is stored in the liver which is released between meals to keep blood sugar levels steady. Below the liver lies the Pancreas which produces hormones that are secreted into the blood and are passed to tissues in the body, the pancreas is full of digestive enzymes which are regularly emptied into the duodenum (Elson, 2013).

Persistent alcohol abuse can lead to liver damage and scarring (cirrhosis). An abnormal accumulation of fat in liver cells can create fatty liver, liver cells are bombarded with globules of fat and in worst case scenario the liver can actually explode. If alcohol is not excreted unchanged, it is converted by enzymes in the liver (known as acetaldehyde), this substance is extremely poisonous to liver cells, alcohol hepatitis occurs as a result of the above causing the liver cells to become inflamed leading to severe damage (Baggeley, 2001).

Digestion and nutrition is a vital part of knowledge for any personal trainer. If you looking to know a little more our team can help. Why not visit us at

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