The main functions of the stomach are to store ingested food, mix it with gastric secretions to begin the digestive process (primarily of proteins), and regulate the emptying of chyme (partially digested food) into the small intestine.
Here's a breakdown of these functions:
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Food Storage: The stomach acts as a temporary storage tank, allowing us to eat meals less frequently. Its muscular walls can expand to accommodate large volumes of food and liquids.
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Mixing and Mechanical Digestion: The stomach's muscular walls contract rhythmically, churning and mixing the food with gastric juices. This physical breakdown, combined with the chemical breakdown, creates a semi-liquid mixture called chyme.
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Chemical Digestion: Gastric glands within the stomach lining secrete gastric juices containing:
- Hydrochloric acid (HCl): Creates a highly acidic environment that helps denature (unfold) proteins and kills bacteria.
- Pepsin: An enzyme that begins the digestion of proteins by breaking them down into smaller peptides.
- Mucus: Protects the stomach lining from the corrosive effects of HCl.
- Intrinsic Factor: Essential for the absorption of vitamin B12 in the small intestine.
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Regulated Emptying: The stomach regulates the rate at which chyme is released into the small intestine. This controlled emptying ensures that the small intestine can efficiently digest and absorb the nutrients. The pyloric sphincter, a muscular valve located at the junction of the stomach and small intestine, controls this process.
In summary, the stomach plays a crucial role in digestion by storing food, initiating protein digestion, and regulating the delivery of partially digested food to the small intestine for further processing and absorption.
