Liver and Pancreas Flashcards
Why is the pancreas described as a ‘dual purpose’ gland?
It has an endocrine and exocrine portion
What is the endocrine portion of the pancreas made up of?
Islets of Langerhans containing clusters of specialised endocrine cells (alpha, beta, delta cells)
Function of endocrine portion of pancreas
releases the hormones insulin, glucagon and somatostatin into the bloodstream (regulates blood glucose)
What portion of the pancreas is endocrine?
1%
What portion of the pancreas is exocrine?
99%
Function of somatostatin
Hormone that has lots of functions including - inhibits glucagon and insulin, reduces acid secretion, slows digestion.
Function of exocrine portion of pancreas
synthesises and releases digestive enzymes and bicarbonate ions
Function of bicarbonate ions in the GIT
Neutralise the acidity (gastric acid) of the chyme which protects the intestine lining. Allow enzymes to function at the optimum pH
Where are digestive enzymes produced/released from?
acinar cells in the exocrine portion of the pancreas
Examples of enzymes released by acinar cells in the exocrine portion of the pancreas
Amylase, lipase, trypsin, chymotrypsin, nucleases
In what form are trypsin and chymotrypsin released from the pancreas?
Inactive form - trypsinogen and chymotrypsinogen.
Why are trypsin and chymotrypsin released in their inactive form from the pancreas?
Trypsinogen and chymotrypsinogen prevent the pancreas breaking itself down. Activated in the small intestine into trypsin and chymotrypsin.
where are bicarbonate ions released from?
Centroacinar cells in the exocrine portion of the pancreas
Divisions of the pancreas
Head - surrounded by C shape of duodenum. Ulcinate process - projection from bottom of head and is posterior to superior mesenteric vein and artery.
Neck - anterior of superior mesenteric artery and vein.
Body - behind stomach
Tail - behind stomach and surrounded by splenorenal ligament.
How do bile and digestive enzymes enter the duodenum?
Via the major duodenal papilla which is controlled by Sphincter of Oddi
Function of gall bladder
stores and concentrates bile
Through which ducts does bile travel to reach the duodenum?
From the gall bladder bile enters the cystic duct which merges with the common hepatic duct to form the common bile duct. The common bile duct joins the pancreatic duct at the major duodenal papilla
Which hormone acts on the gall bladder and pancreas?
Cholecystokinin (CCK)
Function of cholecystokinin (CCK)
Stimulates gall bladder to contract and release bile, stimulates the pancreas to produce/release digestive enzymes, and relaxes the sphincter of Oddi.
Where is cholecystokinin released from?
Cells of the duodenum when chyme enters
What portion of the islet of Langerhan is made of alpha cells?
15%
Where is glucagon secreted from?
alpha cells in the islets of Langerhans
What portion of the islet of Langerhans is made of beta cells?
80%
Where is insulin released from?
Beta cells in the islets of Langerhans
What portion of the islet of Langerhans is made of delta cells?
5%
Where is somatostatin released from?
Delta cells in the islets of Langerhans
Series of actions when low blood glucose is detected
Glucagon released by alpha cells in the islets of Langerhans in the pancreas. Glucagon causes glycogen stores to be broken down into glucose (glycogenolysis) in hepatocytes mainly, and skeletal muscle. Glucose is released into the bloodstream.
When would low blood glucose typically occur?
Early in the morning, before a meal, after exercise
Series of actions when high blood glucose is detected
Insulin released by beta cells in the islets of Langerhans in the pancreas. Insulin causes uptake of glucose from the blood by liver mainly and also skeletal muscle and adipocytes. Glucose is converted to glycogen (glycogenesis).
Which organs can be considered to be lobulated?
Liver and pancreas (contains serous glands)
What type of exocrine gland is found in the pancreas?
Serous glands
What is released by serous glands in the pancreas?
Digestive enzymes and bicarbonate
How are serous glands in the pancreas structured and connected to the pancreatic duct?
Contain a cluster of acinar cells which surround a centroacinar cell that is connected to an intercalated duct. Intercalated ducts from lots of acini merge to form a intralobular duct which leads into the main pancreatic duct.