|PANCREAS-PARTS, RELATIONS, B.S, HISTOLOGY & DEVELOPMENT
|Page 1 of 1|
|Author:||lakshmidr [ 16 Aug 2019 23:47 ]|
|Post subject:||PANCREAS-PARTS, RELATIONS, B.S, HISTOLOGY & DEVELOPMENT|
It is is an elongated “J” shaped or retort-shaped when viewed horizontally, with the bowl of retort represents the head and the stalk of retort is formed by the neck, body, and tail and is soft and lobulated
It is situated retroperitoneally behind the stomach and crosses the midline along the transpyloric plane
It is a glandular organ and is an important part of the digestive system. It performs both exocrine and endocrine functions
The exocrine portion of the gland produces digestive secretions that contains enzymes capable of hydrolyzing proteins, fats, and carbohydrates.
The endocrine portion of the gland, the pancreatic islets (islets of Langerhans), produces the hormones insulin and glucagon, which play a key role in carbohydrate metabolism.
PARTS OF PANCREAS
The pancreas is divided into 5 parts as follows
• Head – It is the widest part of the pancreas and fits within within the C-shaped curve formed by the duodenum, and is attached to it by connective tissue
• Uncinate process – It is a hook like projection of the lower part of the head and extends medially and lies underneath the body of the pancreas. The superior mesenteric vessels lie anterior to the uncinate process
• Neck – lt is the portion between the head and the body of the pancreas. It is anterior to the superior mesenteric vessels which form a groove in its posterior surface.
• Body - It is the central portion of the pancreas and runs across the midline towards the left (refers to the subject’s left hand side) and lies posterior to the stomach
• Tail – It is the tapering left end of the pancreas that lies near the hilum of the spleen. It is situated within the splenorenal ligament together with the splenic vessels. It is the only intraperitoneal portion of the pancreas
RELATIONS OF PANCREAS
RELATIONS OF HEAD
• The head of the pancreas has 3 borders, namely superior, inferior and lateral
• It has 2 surfaces, namely anterior and posterior
• It has one hook like process, on its lower end, the uncinate process
• The superior border is in close proximity to the first part of the duodenum and superior pancreaticoduodenal artery
• Inferior border lies rests on the 3rd part of the duodenum, and inferior pancreaticoduodenal artery.
• Right Lateral border is related to the part of the duodenum, and anterior and posterior pancreaticoduodenal arteries
• The anterior surface is related from right to left to the transverse colon, attachment of transverse mesocolon, the lesser sac and stomach
• The posterior surface is related from right to left to the bile duct, the portal and splenic veins, the inferior vena cave, the aorta, origin of superior mesenteric artery, left psoas, left adrenal gland, left kidney and splenic hilum
RELATIONS OF NECK
• The neck has an anterior and posterior surface and an upper and lower border
• The anterior surface is related to the pylorus of the stomach
• The posterior surface is related to the origin of portal vein
RELATIONS OF BODY
• The body has an anterior, posterior surface and inferior surface and superior, inferior and anterior border
• Anterior surface is related to lesser sac and stomach
• Posterior surface is not covered by peritoneum and is related to aorta and origin of superior mesenteric artery, left adrenal gland and kidney and splenic vein
• Inferior surface is covered by peritoneum and related to duodenojejunal flexure, the jejunum and left colic flexure
RELATION OF TAIL
The tail of the pancreas lies in the lienorenal ligament and is related to the splenic hilum
BLOOD SUPPLY OF PANCREAS
• The pancreas gets its blood supply from the pancreatic branches of the splenic artery.
• In addition, the head is supplied by the superior and inferior pancreaticoduodenal arteries which are branches of the gastroduodenal and superior mesenteric arteries, respectively
• The head of the pancreas is drains into the superior mesenteric branches of the hepatic portal vein. The rest of the pancreas drains into pancreatic veins which empty into the splenic vein
DEVELOPMENT OF PANCREAS
• The pancreas develops from dorsal and ventricular buds of the foregut
• A canalized system forms within the two buds
• The rotation of the stomach and duodenum and the rapid growth of the left side of the duodenum makes the ventral and dorsal buds meet
• Fusion also occurs between the ventral and dorsal pancreatic ducts
• Continued growth of endodermal cells in the dorsal ad ventral buds into the surrounding mesenchyme gives rise to a canalized system that form the collecting ducts
• At the end of the collecting ducts, secretory acini of the exocrine pancreas form
• The islets form as outpouchings from the developing ductal system. Later they lose their connection with the ductal system and form islands of endocrine pancreatic cells that secrete hormones
The pancreas is a glandular organ and has both exocrine and endocrine components. The exocrine pancreas comprises over 99% of the glandular mass and made up of darker staining acinar cells that secrete into a duct system which drains into the pancreatic duct which ends at the ampulla of Vater.
The exocrine acini (glandular structures) are arranged in the form of lobular structures. The acini connect to intercalated ducts, lined by low cuboidal epithelium, which drain into intralobular ducts that coalesce to interlobular ducts that drain into the main pancreatic duct.
In between the lobules of acini, thin connective tissue septae are seen containing blood vessels. The cells of the acini have zymogen granules. The secretions of the exocrine pancreas are alkaline and rich in bicarbonate and contain enzymes including lipase, trypsin, amylase and chymotrypsin.
The endocrine pancreas consists of scattered cellular islands called islets of Langerhans that are composed of lighter staining cells. The cells of the islets secrete hormones into the bloodstream. The cells of the islets are composed of three types of cells namely alpha cells (secrete glucagon), beta cells (secrete insulin) and delta cells (secrete somatostatin).
Lobules of exocrine acini separated by connective tissue septa with
endocrine component islets of Langerhans in the right
|Page 1 of 1||All times are UTC + 5:30 hours [ DST ]|
|Powered by phpBB® Forum Software © phpBB Group