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P2 Digestion
Digestion
• Digestive system is where food is broken down into its individual nutrients. The important nutrients are absorbed into the bloodstream and the waste excreted. It works both through mechanical and chemical digestion.
The technical term for the mouth is the Buccal Cavity where the journey for food begins. The teeth and jaw produce mechanical digestion through mashing and grinding of food. Saliva contains a digestive enzyme called amylase which starts the breakdown of carbs. The tongue helps to mix food and aid swallowing
oesophagus
When food is swallowed it enters the oesophagus, which delivers the food to the stomach through the process of peristalsis (contraction) and gravity. The enzyme amylase continues to break down carbohydrates
StomachFound in the upper left abdominal cavity and is behind the lower ribs. It continues the process of chemical digestion but no absorption of nutrients occurs in the stomach as the pieces are too large. It is made up of three layers of smooth muscle which mixes up the food. Hydrochloric acid helps dissolve the food and kill off any bacteria. Pepsinogen releases here to breakdown Protein
Takes 1-4 hours to empty completely depending on the size
of the meal
Small Intestine
• 90% of digestion takes place here with the help of the pancreas, liver and gall bladder. It is between 3-6m long and is made up of three areas;
1. Duodenum- 25cm2. Jejunum next 2m3. around 3-4m
Partly digested food moves through the small intestine partly from gravity but mainly
peristalsis (contraction). The walls of the intestines absorb all required nutrients and
pass waste into the large intestine.
Pancreas Food doesn’t pass through here but the pancreas releases over 1.5 litres of fluid to aid in digestion. The fluid contains vital enzymes to break down food. Amylase to breakdown carbs, lipase for fats and trypsin for proteins.
Liver
Releases bile to assist the digestion of fats. Food doesn’t pass through here.
Large Intestine
Large intestine (Colon) carries out the following actions;
– Storage of waste before you excrete it
– Absorption of any remaining water
– Production of vit B and K– Breakdown of any toxins
that may damage the colon further down
AnusExcess waste products become hard and concentrated Faeces . The faeces is stored in the rectum for a certain period and then the stored faeces is eliminated from the body due to the contraction and relaxation through the Anus. The exit of this waste material is regulated by the Anal sphincter
