The Gut Wall

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The Gut Wall
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The Gut Wall

• The gut wall is divided into 3 main layers
• An outer muscle layer, protected by a thin
  coating of fibres
• A middle layer, called the submucosa
• An inner layer, called the mucosa

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The structure of the gut wall is not the same all
along the gut. The layers have special features
in different regions that allow that part of the
gut to carry out specific functions.

• The different regions are
• Oesophagus
• Stomach
• Duodenum
• Ileum

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Oesophagus

• Main function - To push food to the stomach.
• Muscle layer Two thick layers force solid food
  along by peristalsis.
• Submucosa Elastic to allow expansion as food
  passes. Glands secrete mucus to lubricate passage
  of food.
• Mucosa Lining has several layers of flattened
  cells outer layers can be rubbed off as food
  passes without causing damage to cells
  underneath. Folds allow expansion as food passes.

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Stomach

• Main function Temporary food store. Muscular
  churning mixes and breaks up food. Hydrochloric
  acid produced kills micro organisms in food.
  Some digestion.
• Muscle layer Three layers run in different
  directions. As the layers contract and relax,
  this creates an effective churning action
• Submucosa Separates muscular and glandular
  layers.
• Mucosa Layer is thick with deep pits. These
  contain many glands that secrete mucus, enzyme
  and acid.

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Doudenum (first 25cm of small intestine)

• Main function Neutralisation of stomach acid.
  Point of entry for Pancreatic juice and bile.
  Digestion and some absorption.
• Muscle layer Two layers for peristalsis.
• Submucosa Contains Brunners glands that
  secrete alkaline mucus. This helps to neutralise
  stomach acid.
• Mucosa Contains many glands that secrete mucus
  and enzymes. Folded into numerous projections
  called villi. These increase the surface area for
  absorption of digested food.

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Ileum (lower part of small intestine)

• Main function Completion of digestion.
  Absorption of products of digestion.
• Muscle layer Two layers peristalsis.
• Submucosa Contains many blood and lymph vessels
  that take up absorbed food and transport them
  around the body.
• Mucosa Similar to Duodenum, but fewer glands.
  Patches of cells called Paneth cells, at base of
  glands, which help defend against bacterial
  infection. Some enzyme production.