Enterocyte

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Overview

WikiDoc Resources for Enterocyte
Articles
Most recent articles on Enterocyte Most cited articles on Enterocyte Review articles on Enterocyte Articles on Enterocyte in N Eng J Med, Lancet, BMJ
Media
Powerpoint slides on Enterocyte Images of Enterocyte Photos of Enterocyte Podcasts & MP3s on Enterocyte Videos on Enterocyte
Evidence Based Medicine
Cochrane Collaboration on Enterocyte Bandolier on Enterocyte TRIP on Enterocyte
Clinical Trials
Ongoing Trials on Enterocyte at Clinical Trials.gov Trial results on Enterocyte Clinical Trials on Enterocyte at Google
Guidelines / Policies / Govt
US National Guidelines Clearinghouse on Enterocyte NICE Guidance on Enterocyte NHS PRODIGY Guidance FDA on Enterocyte CDC on Enterocyte
Books
Books on Enterocyte
News
Enterocyte in the news Be alerted to news on Enterocyte News trends on Enterocyte
Commentary
Blogs on Enterocyte
Definitions
Definitions of Enterocyte
Patient Resources / Community
Patient resources on Enterocyte Discussion groups on Enterocyte Patient Handouts on Enterocyte Directions to Hospitals Treating Enterocyte Risk calculators and risk factors for Enterocyte
Healthcare Provider Resources
Symptoms of Enterocyte Causes & Risk Factors for Enterocyte Diagnostic studies for Enterocyte Treatment of Enterocyte
Continuing Medical Education (CME)
CME Programs on Enterocyte
International
Enterocyte en Espanol Enterocyte en Francais
Business
Enterocyte in the Marketplace Patents on Enterocyte
Experimental / Informatics
List of terms related to Enterocyte

Enterocytes, or intestinal absorptive cells, are simple columnar epithelial cells found in the small intestines and colon. A glycocalyx surface coat contains digestive enzymes. Microvilli on the apical surface increase surface area for the digestion and transport of molecules from the intestinal lumen. The cells also have a secretory role.

Functions

Apical membrane and Basolateral membrane

The major functions of enterocytes include:

• Ion uptake, including sodium, calcium, magnesium, and iron. This typically occurs through active transport.
• Water uptake. This follows the osmotic gradient established by Na+/K+ ATPase on the basolateral surface. This can occur transcellularly or paracellularly.
• Sugar uptake. Polysaccharidases and disaccharidases in the glycocalyx break down large sugar molecules, which are then absorbed. Glucose crosses the apical membrane of the enterocyte using the Na⁺ dependent glucose transporter. It moves through the cytosol (cytoplasm) and exits the enterocyte via the basolateral membrane (into the blood capillary) using GLUT-2 (SLC2A2). Galactose uses the same transport system. Fructose, on the other hand, crosses the apical membrane of the enterocyte, using GLUT-5 (SLC2A5). It is thought to cross into the blood capillary using one of the other GLUT transporters.
• Peptide and amino acid uptake. Peptidases in the glycocalyx cleave proteins to amino acids or small peptides. Enteropeptidase is responsible for activating pancreatic trypsinogen into trypsin, which activates other pancreatic zymogens.
• Lipid uptake. Lipids are broken down by pancreatic lipase and bile, and then diffuse into the enterocytes. Smaller lipids are transported into intestinal capillaries, while larger lipids are processed by the Golgi and smooth endoplasmic reticulum into lipoprotein chylomicra and exocytozed into lacteals.
• Vitamin uptake. Receptors bind to the [[vitamin B12|vitamin BTemplate:Ssub]]-gastric intrinsic factor complex and are taken into the cell.
• Resorption of unconjugated bile salts. Bile that was released and not used in emulsification of lipids are reabsorbed in the ileum. Also known as the enterohepatic circulation.
• Secretion of immunoglobulins. IgA from plasma cells in the mucosa are absorbed through receptor mediated endocytosis on the basolateral surface and released as a receptor-IgA complex into the intestinal lumen. The receptor component confers additional stability to the molecule.

Pathology

Dietary fructose intolerance occurs when there is a deficiency in the amount of fructose carrier.

Lactose intolerance is the most common problem of carbohydrate digestion and is created by an insufficient amount of lactase (a disaccharidase) enzyme, which is used to break down the sugar. As a result of this deficiency, undigested lactose cannot be absorbed and is instead passed on to the colonic bacteria, which metabolize the lactose. The bacteria release gas and metabolic products that enhance colonic motility.

Problems with the gastric intrinsic factor or its receptor can result in pernicious anemia.

External links

• Histology image: 11706loa – Histology Learning System at Boston University - "Digestive System: Alimentary Canal - jejunum, goblet cells and enterocytes"
• Enterocytes at the US National Library of Medicine Medical Subject Headings (MeSH)