Explain how the structure of the villus is related to its role in absorptionThis is a featured page

  • The wall of the small intestine contains millions of fingerlike projections called villi; their fingerlike shape greatly increases the surface area of the intestine thereby speeding up the overall rate of absorption. Absorption is the process by which the nutrients of food move from the small intestine into the bloodstream.
Explain how the structure of the villus is related to its role in absorption - IB Biology Terms

  • Each villus contains a lymphatic vessel called a lacteal, which is adapted to receive fatty acids from the microvilli.

  • And each villus contains a network of capillaries that delivers oxygen to the microvilli so they can perform cell respiration. Microvilli are hundreds of microscopic cells that project into the intestinal lumen from the villus. Like the villus, each microvillus is finger-shaped to further increase the surface area of the intestine for faster absorption.

  • Microvilli are extremely small cells, a feature that allows nutrients to pass through them quickly.

  • Microvilli contain many mitochondria, which allow them to make lots of ATP for the active transport of nutrients into the bloodstream.

  • Microvilli have protein pumps that move monosaccharides and amino acids into the bloodstream.

  • Absorption requires the nutrients to cross four cell membranes: 1) out of the small intestine lumen and into a microvillus cell; 2) out of the microvillus cell; 3) into a capillary cell; 4) out of a capillary cell and into the capillary lumen.

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