The Digestive System
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The Digestive System: Functions and Processes
Overview of Digestion
The digestive system is a complex process essential for processing food to nourish the body and eliminating waste. It breaks down food so that nutrients can be absorbed into the bloodstream.
Stages of Digestion
Food begins its journey in the mouth, where chewing breaks it down into smaller pieces. It then passes through the oesophagus into the stomach and eventually to the small intestine, where digestion and nutrient absorption occur.
The small intestine is crucial for absorption due to its extensive surface area lined with villi, which facilitate rapid nutrient absorption into the bloodstream.
In the large intestine, excess water is absorbed, and undigested food exits the body through the anus.
Role of Liver and Pancreas
The liver produces bile to aid in digesting fats, while the pancreas secretes digestive enzymes that accelerate the breakdown of food.
Function of Digestive Enzymes
Enzymes are proteins that break down large molecules into smaller ones:
- Carbohydrate enzymes start breaking down starch in the mouth with saliva containing amylase.
- Lipase enzymes break down fats and oils, assisted by bile from the liver.
- Protease enzymes break down proteins, aided by stomach acid.
Vitamins, minerals, and water are small enough to be absorbed directly by the body.
Role of Dietary Fibre and Gut Bacteria
The body cannot digest dietary fibre, which aids digestive transit. It passes through the body and is crucial for maintaining bowel health.
Gut bacteria in the digestive system play several roles:
- They digest substances like certain carbohydrates.
- They produce vitamins such as K and B.
- They inhibit harmful bacteria growth, thus reducing the risk of diseases.
About half the dry weight of faeces consists of bacteria, highlighting their importance in digestion and overall health.
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