a-short-review-of-histology

Small Intestine:

The small intestine includes the duodenum, jejunum and ileum
Each part has a similar general morphology which conforms with the basic gut plan
In the small intestine digestion of the food continues but absorbtion of the breakdown products of digestion is also very important
The mucous membrane is thrown into finger like processes known as villi
These project into the lumen of the small intestine and provide an increased surface area for absorbtion
Between the villi, intestinal glands indent into the lamina propria of the mucous membrane
The villi are covered in epithelium
They have a connective tissue (lamina propria) core which supports blood vessels and a lacteal
Lacteals are blind ended lymphatic capillaries that are important in absorbtion of fats
Small bundles of smooth muscle fibres extend from the muscularis mucosae to the tips of the villi
Contraction of these muscle fibres gives some movement to the villus, mixing the luminal contents and improving the absorbtive process
The mucous membrane is covered by a simple columnar epithelium
The epithelium consists mainly of absorbtive cells which have numerous microvilli on their apical surface
The microvilli increase the surface area of the apical surface of the absorbtive cells
Mucus secreting goblet cells are interspersed between the absorbtive cells
Their secretions help to protect the microvilli from the enzymes which are acting on the luminal contents

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