World Library  
Flag as Inappropriate
Email this Article

Intestinal villus

Article Id: WHEBN0000572635
Reproduction Date:

Title: Intestinal villus  
Author: World Heritage Encyclopedia
Language: English
Subject: Small intestine, Coeliac disease, Microvillus, Human gastrointestinal tract, Malabsorption
Collection:
Publisher: World Heritage Encyclopedia
Publication
Date:
 

Intestinal villus

Intestinal villus
Micrograph of the small intestine mucosa showing intestinal villi - top half of image. H&E stain
Section of duodenum of cat. X 60.
Details
Latin villi intestinales
Identifiers
Dorlands
/Elsevier
12857047
Anatomical terminology

Intestinal villi (singular: villus) are small, finger-like projections that protrude from the epithelial lining of the intestinal wall. Each villus is approximately 0.5-1.6 mm in length, and has many microvilli projecting from the enterocytes of its epithelium which collectively form the striated or brush border. Each of these microvilli are much smaller than a single villus. The intestinal villi are much smaller than any of the circular folds in the intestine.

Villi increase the internal surface area of the intestinal walls making available a greater surface area for absorption. An increased absorptive area is useful because digested nutrients (including monosaccharide and amino acids) pass into the semipermeable villi through diffusion, which is effective only at short distances. In other words, increased surface area (in contact with the fluid in the lumen) decreases the average distance travelled by nutrient molecules, so effectiveness of diffusion increases. The villi are connected to the blood vessels so the circulating blood then carries these nutrients away.

Contents

  • Structure 1
    • Histology 1.1
  • Function 2
  • Additional images 3
  • References 4

Structure

Histology

Paneth cells, along with goblet cells, and enterocytes represent the principal cell types of the epithelium of the villi(pl.) on small intestine.[1]

Function

In all humans, the villi and the microvilli increase intestinal absorptive surface area approximately 30-fold and 600-fold, respectively, providing exceptionally efficient absorption of nutrients in the lumen.[2] This increases the surface area so there are more places for food to be absorbed.

There are also enzymes (Enterocyte digestive enzyme) on the surface for digestion. Villus capillaries collect amino acids and simple sugars taken up by the villi into the blood stream. Villus lacteals (lymph capillary) collect absorbed chylomicrons, which are lipoproteins composed of triglycerides, cholesterol and amphipathic proteins, and are taken to the rest of the body through the lymph fluid.

Villi are specialised for absorption in the small intestine as they have a thin wall, about one cell thick, which enables a shorter diffusion path. They have a large surface area so there will be more efficient absorption of fatty acids and glycerol into the blood stream. They have a rich blood supply to keep a concentration gradient.[3]

Villi also help the intestines to move food along the digestive pathways.

Additional images

References

  1. ^ http://www.copewithcytokines.org/cope.cgi?key=Paneth%20cells
  2. ^ http://scienceaid.co.uk/biology/humans/digestion.html


This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 


Copyright © World Library Foundation. All rights reserved. eBooks from Project Gutenberg are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.