ABOUT ISLET OF LANGERHANS

       SMRITI SINGH

                   UNIVERSITY DEPT. OF ZOOLOGY

             S.K.M.UNIVERSITY

       DUMKA-814110

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 INTRODUCTION

Islets of Langerhans known as the insulin producing tissue, islets of langerhans do more than that. They are groups of specialized cells in the pancreas that make and secrete hormones.

 Named after the German pathologist Paul Langerhans(1847-1888),who discovered them in 1869, these cells sit in groups that Langerhans likened to little islands in the pancreas.

WHAT IS PANCREAS

*It is a large gland in body that secrete hormones.

*The cells that make up of pancreatic islet also known as “islets of langerhans”

*It is apart of two different organ sytem

                          - Endocrine system

                          - Digestive system

  There are 4 main cell in the pancreatic islet:

üAlpha cells, which secrete glucagon

üBeta cells, which secrete insulin and amylin

üDelta cells, which secrete somatostatin

üF-cells, which secrete pancreatic polypeptide

LOCATION

vWhole a located in the epigastric and left hypochondriac

         regions and its right part lies across

         the bodies of L1 to L3 vertebrae.

vIt runs transversely across the posterior abdominal

       wall behind the stomach, from the duodenum

       to the spleen, sloping upward from right to left.

vIt is approximately 12.6 – 15cm

       long and weighs from 60 – 100gm.

   

LOCATION OF ILET OF LANGERHANS IN PANCREAS

ILET OF LANGERHANS 

Islet of Langerhans is an endocrine part of pancreas surrounded by pancreatic acinus or lobule.

The pancreatic acinus is the exocrine part of pancreas.

 The islets consisting special four different cells surrounded by connective tissues and blood space identified by a German pathologist, physiologist and biologist “Paul Langerhans”. Hence, it is named as islet of langerhans.

*Islet of langerhans is highly vascular part secreting hormones in the blood. Four types of islet cells are embedded in a vascular belt.

*These cells are –

         1. alpha cell 20% secret glucagone composed of 29AA residue with a mol.weight of 3482.

     2. Beta cell  50% secret insulin are composed of 51AA residues with a mol.weight of 5808. It is composed of two chains- (a) alpha chain of 21AA &

                                                      (b) beta chain of 30AA.

It is usually associated zinc(Zn++) and protein and stored in cytoplasm of beta cell. A healthy human species produces 2mg insulin/day. It is released into blood.

     3.Delta cell/D cells of the islet secret somatostatin , a polypeptide of 14AA which regulated the movement of nutrients from gut to the blood and oher body fluids.

     4.F-cell/PP cells  of the islets produce a pancreatic polypeptide (PP) of 36AA.