Functions of the Organs
The Mouth
The mouth is the start of the digestive system which breaks down food by the teeth and
creates saliva through the salivary glands. This softens the food so it's easier to swallow and
transport through the oesophagus. It also contains enzymes called amylase to break down
starch from food into sugars. Secreting saliva is chemical digestion and chewing the food is
mechanical digestion. (NIDDK, 20)
The Oesophagus
Next is the oesophagus which connects the mouth and the stomach in the digestion process.
“It is a muscular tube that connects the pharynx (throat) to the stomach.” (Michigan
Medicine, 20) The oesophagus contracts its muscles as it moves food into the stomach like
a tube of toothpaste being squeezed, this contraction is called peristalsis
The Stomach
Then the stomach takes food from the oesophagus where it is then broken down by
enzymes such as pepsin that serves to digest proteins found in ingested food Pepsin also
“releases a small peptides and amino acids (peptones) stimulate the release of gastrin from
antral G cells; these peptones also stimulate CCK release from duodenal I cells.” (Science
Direct, 20) Peptide bonds are found in sugars, Parietal cells within the stomach lining
secrete hydrochloric acid which hydrolyzes the glycosidic bonds and then lowers the pH of
the stomach. The stomach holds food until it is ready to empty into your small intestine.
The Liver
Furthermore the liver produces bile which allows you to break down fatty acids and turn
them into energy that your body uses. Your liver also creates albumin “This is a blood protein
that helps carry hormones, drugs, and fatty acids throughout your body.” (Hopkins Medicine,
20) Your liver also creates most of the substances that help your blood clot after injury.
When you take in a potentially toxic substance, like alcohol or medicine, your liver helps alter
it and remove it from your body. The body contains Bicarbonate salts which balances the pH
and prevents it from getting acidic (neutralises acids).
The Pancreas
After that the pancreas' role in digestion is regulating the level of sugar in your blood. It also
creates natural juices called pancreatic enzymes to break down foods. These juices travel
through your pancreas via ducts. They empty into the upper part of your small intestine
called the duodenum. The juices are lipase, protease and amylase (more detail about these
enzymes below). (Mayo Clinic, 20)
The Small Intestine
The small intestine is an organ that absorbs nutrients of food through villi into the
bloodstream glucose and amino acids pass into the capillaries inside each villi (Image A
description of Villi). It absorbs (vitamins, minerals, carbohydrates, fats, proteins) and water
from food so they can be used by the body (National Cancer Institute, 20). These are
broken down by enzymes when they form enzyme-substrate complexes which decrease the
energy needed for reactions, allowing enzymes to act as a catalyst; maltase which plays a
role in the digestion of starches, lactase which digests lactose and dairy products, sucrase
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