The small intestine is the longest part of the digestive system, measuring around 20 feet in length.
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It consists of three sections: the duodenum, jejunum, and ileum, each with distinct functions in the absorption process.
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The small intestine's inner lining is lined with finger-like projections called villi, which significantly increase the surface area for nutrient absorption
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Each villus is covered with even smaller projections called microvilli, forming a brush border that further enhances the absorption surface.
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The total surface area of the small intestine, including the villi and microvilli, is estimated to be about 2,700 square feet (250 square meters) - roughly the size of a tennis court!
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The small intestine is richly supplied with blood vessels, ensuring efficient nutrient exchange between the intestinal wall and the bloodstream.
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Nutrient absorption primarily occurs in the jejunum, where the villi are the longest and most abundant.
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The small intestine employs active transport mechanisms to absorb nutrients, allowing it to move nutrients against concentration gradients and maximize absorption efficiency.
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Along with absorbing nutrients, the small intestine also absorbs vitamins, electrolytes, and water, contributing to overall hydration and nutrient balance.
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The small intestine possesses specialized cells called enterocytes, which are responsible for absorbing and transporting nutrients into the bloodstream.
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The small intestine is constantly in motion, undergoing rhythmic contractions called peristalsis that propel digested food and enhance absorption.
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The absorption of fats occurs differently from other nutrients. Fats are broken down into tiny droplets called micelles, which are then absorbed by the intestinal cells.
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The small intestine has a remarkable ability to adapt its absorptive capacity to meet the body's needs, adjusting nutrient uptake based on dietary factors and physiological conditions.
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