Islets of Langerhans

From Psychology Wiki

Community portal · Tasks to do · News · Help

Clinical · Educational · Ind&Org · Other fields · Professional · Transpersonal · World

Assessment | Biopsychology | Comparative | Cognitive | Developmental | Language
Personality | Philosophy | Research Methods | Social | Statistics

Biological: Behavioural genetics · Evolutionary psychology · Neuroanatomy · Neurochemistry · Neuroendocrinology · Psychoneuroimmunology · Physiological Psychology · Psychopharmacology

A porcine islet of Langerhans. The left image is a brightfield image created using hematoxylin stain; nuclei are dark circles and the acinar pancreatic tissue is darker than the islet tissue. The right image is the same section stained by immunofluorescence against insulin, indicating beta cells.

Islets of Langerhans, haemalum-eosin stain.

Section of pancreas of dog. X 250.

The endocrine (i.e., hormone-producing) cells of the pancreas are grouped in the islets of Langerhans. Discovered in 1869 by the German pathological anatomist Paul Langerhans, the islets of Langerhans constitute approximately 1 to 2% of the mass of the pancreas. There are about one million islets in a healthy adult human pancreas, which are interspersed evenly throughout the organ, and their combined weight is 1 to 1.5 grams. Each islet contains approximately one thousand cells and is 50-500 μm in diameter.

[edit] Cell types

Hormones produced in the Islets of Langerhans are secreted directly into the blood flow by (at least) four different types of cells:

• Beta cells producing Insulin and Amylin (65-80% of the islet cells)
• Alpha cells releasing Glucagon (15-20%)
• Delta cells producing Somatostatin (3-10%)
• PP cells containing polypeptide (1%)

Islets can influence each other through paracrine and autocrine communication, and beta-cells are coupled electrically to beta-cells (but not to other cell-types).

[edit] Paracrine feedback

The paracrine feedback system of the islets of Langerhans has the following structure:

• Insulin: Activates beta cells and inhibits alpha cells.
• Glucagon: Activates alpha which activates beta cells and delta cells.
• Somatostatin: Inhibits alpha cells and beta cells.

[edit] Electrical activity

Electrical activity of pancreatic islets has been studied using patch clamp techniques, and it has turned out that the behavior of cells in intact islets differs significantly from the behaviour of dispersed cells.

[edit] As a treatment for type I diabetes

Since the islets of Langerhans are destroyed in type I diabetes, clinicians and researchers are actively pursuing islet transplantation technology as a means of curing this disease.

[edit] External links

• MeSH A03.734.414
• Histology at OU 80_14 - "Pancreas"

This page uses content from the English-language version of Wikipedia. The original article was at Islets of Langerhans. The list of authors can be seen in the page history. As with Psychology Wiki, the text of Wikipedia is available under the GNU Free Documentation License.