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Absorption in the digestive system is the process by which nutrients from digested food are taken into the bloodstream. Here's a step-by-step explanation:
1. Mouth (Initial Breakdown)
Digestion begins in the mouth, where enzymes in saliva start breaking down carbohydrates. However, absorption doesn't occur here.
2. Stomach (Minimal Absorption)
The stomach breaks down proteins and churns food into a semi-liquid called chyme.
Minimal absorption happens in the stomach, mostly for alcohol and some medications.
3. Small Intestine (Major Absorption Site)
Duodenum: Chyme enters the duodenum where bile (from the liver) and pancreatic enzymes further digest fats, proteins, and carbohydrates.
Jejunum: Nutrients like sugars, amino acids, fatty acids, and vitamins are absorbed here through the intestinal walls into the bloodstream.
Ileum: Remaining nutrients, particularly bile salts, vitamin B12, and some water, are absorbed here.
4. Villi and Microvilli (Maximizing Absorption)
The small intestine is lined with tiny finger-like structures called villi and smaller projections called microvilli, which increase the surface area for maximum nutrient absorption.
5. Nutrient Transport
Absorbed nutrients enter the bloodstream through capillaries in the villi and are transported to the liver for processing.
Fats are absorbed into the lymphatic system first and later enter the bloodstream.
6. Large Intestine (Water Absorption)
The large intestine absorbs water, salts, and some vitamins.
Any undigested material forms stool, which is eventually excreted.
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