2 Major Functions of the Digestive system
= For Therapists =
It is essential for therapists to have a good knowledge of the process of digestion in order to understand how the body utilises nutrients for efficient and healthy body functioning.
Understanding the structure of the digestive system and its links with the parasympathetic nervous system can also help therapists to understand the link between digestive disorders and stress.
The alimentary tract is a long continuous muscular tube extending from?
Digestion is The breakdown and transformation of solid and liquid food into microscopic substances. These substances are then transported by the blood into different areas of the body.
There are four stages of digestion:
- Mouth: ingestion (the taking in of food or liquid into the body), chewing and swallowing; start of starch digestion
- Stomach: mixing and protein digestion
- Small intestine: carbohydrate and fat digestion; absorption
- Large intestine: waste and excretion.
- mouth to anus
- stomach to anus
- small intestine to anus
- large intestine to anus
Which of the following completes digestion?
The act of taking food into the alimentary canal through the mouth.
Mechanical digestion – known as mastication. the breaking down of solid food into smaller pieces by the chewing action of the teeth. the churning action of the stomach assisted by peristalsis.
Chemical digestion – the breakdown of carbohydrates, proteins and fats into smaller ones by the action of digestive enzymes.
The movement of soluble materials out through the walls of the small intestine. Nutrients are absorbed through the villi and pass out into the network of blood and lymph vessels.
This is the expulsion of the semi-solid waste called faeces through the anal canal.
- small intestine
- large intestine
Trypsin is an enzyme produced by what?
WHAT ARE CARBOHYDRATES?
Carbohydrates are classified as monosaccharides, disaccharides or polysaccharides. Monosaccharides include fructose in fruit.
Disaccharides include lactose in milk. Polysaccharides include starch and fibre in cereals, potatoes and other plant sources, and glycogen in meat. All carbohydrates are broken down to monosaccharides for absorption and all eventually become glucose to supply the body with energy.
Carbohydrates are broken down in the body by the following processes:
- In the mouth, salivary amylase begins the breakdown of polysaccharides
- In the small intestine, intestinal amylase breaks down polysaccharides to disaccharides
- In the small intestine, maltase, lactase and sucrase convert disaccharides to monosaccharides ready for absorption.
WHAT ARE PROTEINS?
Proteins foods include dairy products, meat, fish and beans. They are made up of interlinked polypeptide chains and are the building material for the body. In order to be used by the body they must be broken down into their smaller components – amino acids.
There are approximately 20 amino acids classified by whether they are essential (those the body cannot make, that must therefore be supplied in the diet) and non-essential (those the body can make).
Proteins are broken down in the body by the following processes:
- In the stomach, the enzyme pepsin begins the digestion of proteins in the stomach by breaking them down into large polypeptides.
- In the small intestine, enzymes from the pancreas, including trypsin and chymotrypsin, break the large polypeptides into smaller chains.
- Finally, still in the small intestine, enzymes from the intestine, including aminopeptidase, breaks up the small polypeptides into individual amino acids ready for absorption.
WHAT ARE FATS?
Fats are classified into saturated, monounsaturated or polyunsaturated categories. Saturated fats can be found in dairy products and meat. Monounsaturated fats can be found in olive oil and avocados. Polyunsaturated fats can be found in sunflower oil and oily fish. Some polyunsaturated fats cannot be made by the body and are therefore also classified as essential fats and must be consumed in the diet. In order to be used by the body, fats must be broken down to fatty acids and glycerol.
Fats are broken down in the body by the following processes:
- In the small intestine, fat are emulsified by bile salts from the liver (i.e. turned into liquid form and carried in another liquid – bile)
- In the small intestine, lipase from the pancreas breaks down emulsified fats into fatty acids and glycerol ready for absorption
- gall bladder