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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