Histological structure of pancreas||Human physiology||

Histological structure of pancreas:

Describe the Histological structure of pancreas? Make a short note on the Histological structure of pancreas?

Introduction to pancreas:

The pancreas(pan-all,kreas-flesh)is an elongated, soft, finely lobulated, acessory digestive gland.

• The pancreas is a J shaped digestive gland.
  The length of the pancreas is 12to15cm, It's width is 3to4cm, weight is 80 to 90gm and thickness is 1.5 to 2cm.
  

  Location of pancreas:   

Pancreas Location.png , Image by-BruceBlaus ,Source , License-CC BY-SA4.0 

The pancreas extends from the concavity of the duodenum,on the right to the spleen and on the left in the posterior abdominal wall retroperitoneally.

Anatomical division of pancreas:

Anatomically the pancreas consists of four parts namely Head, Neck,Body,Tail,.

Head: It is the enlarged,disc shaped right end of the pancreas.

Neck: It is slightly constricted part of the pancreas, which helps in the joining of the head with the body.

Body: it lies in front of the vertebral column,at or below the transpyloric plane.It extends from the neck to the tail.

Tail:It lies in the lienorenal ligament along with splenic vessels.It is the narrow,left extremity of the pancreas.

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Physiological division of pancreas:

Physiologically, depending upon the functions preformed by the pancreas,it is divided into two parts exocrine and endocrine part.

File:Pancreatic-Model-of-Exocrine-and-Endocrine-Function-Locations.jpg, Source , License-CC BY-SA4.0

⏺️ Exocrine part of the pancreas :

The exocrine part of the pancreas is in form of compound tubulo alveolar serous gland.

It resembles salivary gland in structure.

Exocrine part of the pancreas is formed by acini or alveoli.

Each acinus is made up of a single layer of acinar cells,with a lumen in the center.In the acinar cells, present numerous secretory granules or zymogen granules.

• From the lumen of each alveolus ,a Small duct arises.Some these ducts from the neighbouring alveoli join  with each and form a structure, known as intra lobular duct.
• All the intralobular duct then joins with each other to form the main duct of pancreas, known as duct of wirsung,
• Wirsung duct then joins with the common bile duct to form the ampulla of vater,it then opens into the duodenum.
• In some person an accessory duct called duct of Santorini exists,it also opens into the duodenum, proximal to the opening of ampulla of vater.

Pancreatic ducts:

The secretions produced by the acini is then received by  the intercalated ducts which then pass on to the inter- lobuler duct.

Finally with the help of main and accessory pancreatic duct ,the pancreatic secretions reaches into the duodenum.

▶️ Main pancreatic duct:

• It is also known as a duct of Santorini.It begins in the tail of the pancreas and traverses the whole length of the gland near it's posterior surface.
• At the neck region, it then turns downward,and then turn to the right to entero in the second part of the duodenum.

• ⏺️Accessory pancreatic duct ,is also known as duct of Santorini ,it starts from the lower region of the head of the pancreas and then runs upward and medially crossimg in front of the main pancreatic duct.

• It then opens into the second part of the duodenum on the summit of minor duodenal papilla ,about 2to 3 cm above the opening of the main pancreatic duct.

⏺️Endocrine pancreas:

The endocrine pancreas is in the form of numerous rounded collection of cells, that are embedded within the exocrine part.These collections of all cells are known as islets of Langerhans or the pancreatic islets.

There is a delicate capsule present around each islet.

In sections it is very difficult to distinguish the islets cells from each other,but in fact three secretory cells types are present:

1. Alpha-secrete glucagon.

In the islets of the human pancreas,the alpha cells also known as A cells ,tend to be arranged towards the periphery of the islets.

1820 The Pancreas.jpg , Image by-OpenStax College , Source, License-CC BY3.0

2.Beta-secrete insulin

The beta also known as B cells, tend to lie near the centre of the islet.

3.Delta-secrete glucagon

Delta cells also known as D cells , like the A cells also peripherally situated.

-The islet are supplied by up to three arterioles,which form a branching network of fenestrated capillaries, into which the hormones are secreted.

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