Describe the adaptations of the ileum to its function. (20) marks

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  • Has secretory glands / crypts of lieberkun which secrete enzymes (maltase / sucrose / peptidase / lipase to complete digestion of lipids / sugar /proteins.
  • Has goblet cells which secrete mucus allowing for smooth movement of food ;and protect wall of ileum from action of digestive enzymes.
  • Very long to provide large surface area for absorption
  • Highly folded / coiled to slow movement of food to allow more time for digestion / absorption / increase surface area for absorption.
  • Highly coiled to fit in the small space in the abdomen.
  • Has numerous villi which increase surface area for absorption / microvillus which further increase surface area for absorption.
  • Ileum wall / villi have thin epithelium which is only one cell thick to reduce distance over which digested food has to diffuse.
  • Villi are highly vascularised / have a rich network of blood capillaries for rapid transport of absorbed from small intestines; and to maintain a steep concentration gradient for efficient absorption..
  • Villi have lacteals for absorption of fatty acids and glycerol
  • Cells of ileum wall have a large count of mitochondria to release energy that aid in active transport across the epithelium.
  • Walls have circular and longtudinal muscles for peristalsis.
Max 20mks

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Has secretory glands/crypts of lieberkuhn which secretes enzymes (maltase/sucrase/lactase/peptidase/lipase to complete digestion of sugars/proteins/lipids. Goblet cells secrete mucus which allows for smooth movement of food and protect wall of ileum from action of digestive enzymes Very long to provide large surface area for absorption. Highly folded/coiled to slow movement of food to allow more time for digestion/absorption/ and to increase surface area for absorption. Has numerous villi which increase surface area for absorption/microvilli which further increase surface area for absorption. Ileum wall/villi have thin epithelium which is only one cell thick to reduce distance over which digested food has to diffuse. Villi are highly vascularised/have a rich network of blood capillaries for rapid transport from small intestines and maintain a steep concentration gradient for rapid absorption. Villi have lacteals for absorption of fatty acids and glycerol Cells of ileum wall h...
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