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.
What cells are found in the acini of serous glands in the pancreas?
Acinar cells which cluster around a centroacinar cell
Function of acinar cells in the serous glands of the pancreas?
synthesise/release digestive enzymes
Function of centroacinar cells in serous glands in the pancreas
Release bicarbonate ions (and mucin) and connect the acini to the intercalated duct.
Function of intercalated ducts in the pancreas
Transport secretions from the acini to an intralobular duct
Function of an intralobular duct in the pancreas
Transport acini secretions from multiple intercalated ducts to the main pancreatic duct
Function of the main pancreatic duct
collects the secretions from all the acini and transports them to the major duodenal papilla
Examples of diseases that can affect the pancreas
Cystic fibrosis and pancreatic cancer
Which portion of the pancreas is affected by cystic fibrosis and why?
Exocrine portion - abnormal, thick, mucous secretions can block ducts and the sphincter of Oddi. Prevents bile and digestive enzymes entering the duodenum.
Effects of destruction of exocrine pancreas / blocked ducts due to CF
Proteins, lipids, carbs and nucleic acids not broken down and lipids not emulsified. Reduced digestive function, malabsorption, steatorrhea (fatty faeces)
Organs affected by cystic fibrosis
Sinuses (sinusitis), lungs (thickened wall, thick mucus, bacteria infection), Skin (salty sweat), Liver (blocked biliary ducts), Pancreas, Intestines (malabsorption), reproductive organs, salivary glands
What hand feature may indicate cystic fibrosis or a heart/lung condition?
Clubbed fingers
Histologically, what will be seen in an individual with cystic fibrosis?
Inflamed lamina propria (causes lack of digestive enzymes in pancreas, thickens airway walls…?)
Why does pancreatic cancer often have a bad prognosis?
Early metastasis - spreads to other areas before symptoms/detection
What is obstructive jaundice?
Yellowing of skin and sclera of eyes due to a biliary obstruction in the head of the pancreas which causes bile (containing bilirubin) to accumulate in pancreas.
Functions of the liver
Detoxifies and processes material absorbed from GIT, stores glycogen, releases glucose, synthesises proteins, inactivates hormones and drugs, excretes waste, produces bile
Why can liver disease have a lot of effects?
Because the liver has many functions
Why can liver disease reduce blood clotting ability?
Liver synthesises blood clotting proteins and platelets. Without this, wounds will bleed more easily / more bruising.
Why can a paracetamol overdose cause liver damage / systemic failure / death?
The normal metabolism for breaking down paracetamol is overwhelmed so a different pathway is taken which produces toxic compounds.
Weight of liver
about 1.5kg
Which abdominal regions can the liver span
Right hypochondrium, epigastric, left hypochondrium
What are the lobes of the liver?
Right, left, quadrate, caudate lobe
Where is the gall bladder located?
Posterior to the liver between its quadrate and right lobe.
Why is there an impression on the posterior of the right lobe of the liver?
Due to the right kidney
Names of ligaments found in the liver
Falciform ligament, round ligament, ligamentum venosum
Function of falciform ligament
Anchors the liver to the anterior abdominal wall and the diaphragm
What structure divides the liver into right and left lobes?
Falciform ligament
What is the round ligament?
The free edge of the falciform ligament. A remnant of the umbilical vein used to bypass the liver while it was still developing so blood can go to the heart.
What is the ligamentum venosum?
A remnant of the ductus venosus
What is the ductus venosus?
Connects the umbilical vein to the inferior vena cava in fetal circulation. Used to bypass the liver while it is still developing.
What are the 3 major vessels that enter the liver?
The proper hepatic artery, hepatic portal vein and the common hepatic duct.
Where do the 3 major vessels enter the liver?
Porta hepatitis
Where does the proper hepatic artery come from?
Branches off the abdominal aorta in the coeliac trunk
What is meant by the dual supply to the liver?
The liver receives 25% of its oxygen supply from the proper hepatic artery and 75% from the hepatic portal vein (as well as lots of nutrient)
Where is bile produced?
In hepatocytes in the liver
Content of bile
Lipid emulsifiers (bile salts formed by cholesterol), and waste products including bilirubin
What is bilirubin?
Bilirubin is the yellow/green bile pigment which gives faeces its brown colour. Produced as a waste product from the breakdown of erythrocytes.
Describe the biliary system in the liver
Bile canaliculi drain into intrahepatic ducts which merge to form the left and right hepatic ducts. The left and right hepatic ducts merge to form the common hepatic duct. The cystic duct from the gallbladder joins the common hepatic duct to form the common bile duct which joins the pancreatic duct at the major duodenal papilla.
What technique can be use to visualise the biliary system?
Endoscopic Retrograde Cholangiopancreatography - ERCP
Which vein drains unpaired abdominal organs? e.g. liver, pancreas, spleen, stomach
Hepatic portal vein - contains almost all GIT absorbed material to be processed by the liver
Why is the hepatic portal vein not a true vein?
Supplies blood to the capillaries in the liver first, not directly to the heart.
Which veins join to form the hepatic portal vein?
Superior mesenteric vein (R gastroepiploic vein merges), splenic vein, gastric veins.
Name of large capillaries between hepatocytes in which blood flows
Sinusoids
Structure of a liver lobule
Hexagonal with a portal triad in each of the 6 corners. Blood from the portal triad flows down sinusoids to the central vein. Bile produced by hepatocytes flows down bile canaliculi to the bile ductule in the portal triad.
How is the liver drained of blood?
Blood flows down sinusoids into the central vein of each lobule. Central veins join to form the hepatic vein which drains into the inferior vena cava.
What makes up the portal triads?
Hepatic arteriole, Hepatic portal venule, bile ductule
Name of immune cells found in the liver
Kupffer cells
What is hepatomegaly?
Enlargement of liver. Can be caused by heart failure, cancer, liver problems.
What is cirrhosis?
Scarring of the liver due to alcohol consumption and liver infections (e.g. viral hepatitis)
What is viral hepatitis?
Inflammation of the liver
What is obstructive jaundice?
Blockage of the bile duct leading to a build up of bilirubin (causes bilirubin to seep into bloodstream leading to jaundice)
What is hepatic carcinoma?
Liver cancer (can be linked to cirrhosis)
