Case 3 Flashcards
The pancreas is mostly posterior to what organ?
The stomach
What is left and right of the pancreas?
The spleen is on the left and the duodenum is on the right.
Where is the pancreas in respect to the peritoneum?
It is retroperitoneal except for a small part of its tail.
How long is the pancreas?
roughly 15cm
What does the uncinated process of the pancreas extend behind?
The superior mesenteric vessels.
What vessel is formed by the combination of the superior mesenteric vein, and splenic vein?
The portal vein
Describe the course of the pancreatic duct through the pancreas?
It begins at the tail, passes through the body and turns left before entering the head.
Where does the pancreatic duct meet up with the bile duct? What does this form?
They meet in the lower part of the head of the pancreas. This forms the hepatopancreatic ampulla/ampulla of vater.
Where does the hepatopancreatic ampulla/ampulla of Vater meet the duodenum what surrounds this opening?
The major duodenal papilla. It is surrounded by the sphincter of ampulla/ sphincter of Oddi
What are the seven arteries that supply the pancreas?
The gastroduodenal, anterior superior pancreaticoduodenal, posterior superior pancreaticoduodenal, dorsal pancreatic, great pancreatic, anterior inferior pancreaticoduodenal and posterior inferior arteries.
Which arteries that supply the pancreas originate from the SMA?
The anterior & posterior inferior pancreatic arteries
Which artery that supplies the pancreas is a branch of the celiac trunk?
The gastroduodenal artery,
Which two arteries that supply the pancreas arise from the gastroduodenal artery
the anterior and posterior superior pancreaticoduodenal arteries.
Which two arteries that supply the pancreas originate from the splenic artery?
The dosal and great pancreatic arteries.
The fusion of what vessels forms the portal venous system?
The SMV and splenic veins
Where does the portal vein lie in respect to the inferior vena cava?
It lies in front of it
The pancreatic acini are each lined with what kind of epithelium?
simple cuboidal epithelium
What is the name for the mix for ions water and and digestive enzymes secreted by the pancreas?
Pancreatic juice
What are the two main hormones secreted by the islets of langerhans into the bloodstream?
insulin and glucagon
What does the sphincter of oddi surround?
The apulla of Vater
What are the three main groups of food that the pancreas helps to digest?
fats, carbohydrates and proteins.
Trypsin, chemotrysin and carboxypolypeptidase all help digest which food group?
Protein
What are the three main peptidases released by the pancreas?
Trypsin, chemotrypsin and carboxypolypeptidase
What is the role of pancreatic trypsin?
It splits partialy digested proteins into peptides of various sizes but does not cause individual amino acid release.
What is the most abundant pancreatic peptidase?
trypsin
What is the role of chemotrypsin?
splits whole and partial digested proteins into petides of varioussizes, does not cause the release of individual peptides
What is the role of carboxypolypeptidase?
Splits peptides into amino acids completing the digestion process
Which of the three main pancreatic peptidases can break peptides down to individual amino acids/
Carboxypolypeptidase
What is the role of pancreatic amylase?
to hydrolyse starches, glucogen and most other carbohydrates to form di and trisaccarides.
What are the three main fat digesting enzymes released by the pancreas?
pancreatic lipase, cholesterolesterase, and phospholipase
How does pancreatic lipase aid fat digestion?
It hydrolyses neutral fat into fatty acids and monoglycerides.
How does cholestorolesterase aid fat digestion?
It causes the hydrolysis of cholesterol esters
How does phospholipase aid fat digestion?
It splits fatty acids from phospholipds
What are the proteolytic enzymes of the pancreas released as when are they converted into their active form?
They are released as trypsinogen, chymotrypsinogen and procarboxypolypeptidase and they are activated once they reach the digestive tract.
What activates trypsinogen?
enterokinase or other molecules of activated trypsin.
What prevents the proteolytic enzymes of the pancreas from digesting the pancreas itself?
Trypsin inhibitor
What are the three phases of pancreatic secretion they are the same as the phases of secretion of what other organ?
Cephalic, gastric and intestinal, same as the stomach
Name three factors that increase the secretory function of the pancreas.
Acetylcholine, cholecytokinin (CCK) and secretin
Nerve endings from what nerve stimulate secretion in the cephalic stage of secretion?
vagus
The cephalic stage of pancreatic section is responsible for what proportion of total pancreatic secretion?
20%
The gastric phase of pancreatic secretion is responsible for what proportion of pancreatic secretion?
5-10%
What is the hormone that
is most responsible for the copious amount of pancreatic secretion in the intestinal phase of pancreatic secretion?
Secretin
How is secretin release?
In its inactive form prosecretin
How many amino acids does secretin contain?
27
Where is secretin released from?
S cells in the mucosa of the duodenum and jejunum
When is secretin released?
When acidic chyme with a pH of 4.5-5 enters the duodenum.
At what pH do pancreatic enzymes function best?
pH 7.0-8.
How many amino acids does cholecystokinin (CCK) contain?
33
Where and when is CCK released?
It is released by I cells in the mucosa of the duodenum and upper jejunum in response to the presence of proteoses and peptones, (products of partial protein digestion) and long fatty acid chains
What cell types is responsible for the initial portion of bile secretion?
Hepatocytes
The initial secretion of bile is high in what three constituents?
Bile acids, cholesterol and other organic constituents
The initial portion of bile secreted by the hepatocytes is secreted into what?
the bile canaliculi between hepatic cells
describe the course of bile from the hepatoocytes
From the hepatocytes bile travels via bile canaliculi towards interlobular septa where they then empty into terminal bile ducts. From there they travelvia progressively larger ducts reaching the hepatic duct and common bile duct.From here it either empties into the duodenum of is diverted via the cytic duct into the gall bladder.
What does the second stage of bile secretion add to the bile?
A watery solution of sodium and bicarbonate ions.
When bile is diverted away from the duodenum to be stored in the gall bladder what duct does it travel via?
The cystic duct.
How are bile salts produced?
Their precursor is cholesterol which is converted into cholic acid and chenodeoxycholic acid in equal amounts these are then combined with glycine and taurine to form conjugated bile acids.
What are the two main functions of bile salts?
Emulsification of fats and help in the absorption of fatty acids monoglycerides, cholesterol and other lipids through the formation of micelles
Where are Brunner’s glands located?
In the first few cm’s of the duodenum
Brunner’s glands secrete large amounts of alkaline mucous in response to what three scenarios?
Tactile or irritating stimuli on the duodenal mucosa, vagal stimulation and gastrointestinal hormones especially secretin
What type of innervation inhibits Brunner’s glands?
sympathetic stimulation
Where are crypts of Lieberkuhn located? How far do they extend?
in between intestinal villi they extend into the muscularis mucosae
What are the six cells types in the Crypts of Lieberkuhn start with the two most frequent.
Goblet cells, enterocytes, kuhn?paneth cells, endocrine cells, stem cells and intraepithelial lymphocytes.
What is the role of the goblet cells in the crypts of Liebekuhn
To secrete protective/lubricating mucous
What is the role of the enterocytes in the crypts of Lieberkuhn?
They secrete large quantities of water and elecctrolytes and reabsorb these along with the end products of digestion.
Which sucrases are thought to be within enterocytes?
sucrase, maltase, isomaltase and lactase
Where in the crypts of Lieberkuhn are paneth cells what is their function?
They are at the base of the crypts and contain antimicrobial peptides including defensins, lysozyme and phopholipase A
What is the role of the endocrine cells in the crypts of Lieberkuhn?
They produce somatostatinm enteroglucagon and serotonin (thought there is one type of endocrine cell for each hormone.
What do the stem cells in the crypt of Lieberkuhn go on to form?
enterocytes, goblet cells paneth cells and neuroendocrine cells.
What type of cell are the majority of intraepithelial lymphocytes?
T cells
What are the three main carbohydrates in the human diet?
sucrose, lactose and starches
What is sucrose composed of?
fructose and glucose
What is lactose composed of?
galactose and glucose
What is the main protein that pepsin helps break up?
collagen
What is the main protelytic enzyme in the stomach?
pepsin
What is the function of the enzyme elastase?
It helps break up elastin fibres that hold meat together.
Which are the two most important peptidases for the last stage of protein digestion?
Aminopolypeptidase and dipetidases
In what cell are di and tripeptides taken into to be broken down into their constituent amino acids?
Enterocytes.
Where are triglycerides first exposed to digestive enzymes which enzyme is this and where is it released?
Triglycerides are forst exposed to lingual lipase in the mouth released by lingual glands
When might water be transported into the GI tract from the small intestines?
When hyperosmotic solutions are discharged from the stomach.
How is the majority of water and Na absorbed from the GI tract?
The basolateral membrane activelty transports sodium out of the cell reducing intracellular Na. Na travels down the created electrochemical gradient through the brush border into the luminal cells. Water then travels through the tight juctins into the paracellular spaces
Where is Aldosterone released from what is its effect?
It is released by the adrenal glands and activates transport mechanisms for Na
How does the majority of Chlorine enter the body through the GI tract?
diffusion
How are calcium ions absorbed?
active transpot
most glucose is absorbed via cotransport with what ion?
Na
Where in the ileum are vitamin B12 and bile salts absorbed?
In the terminal ileum
Which type of carbohydrate is converted into glucose in order to aid it’s transport?
fructose
Which organelle sequesters fats once they have entered the small intestinal mucosa?
The smooth endoplasmic reticulum.
What are the two main transport proteins that aid with fat absorption?
FAT(P1) and CD36
What provides the energy required for protein absorption?
A Na cotransport mechanism.
There are at least how many different transport systems for absorbing amino acids?
7
How many amino acid transport systems require Na and cotransport it
5
How many of the five amino acid transport systems that require Na also require Cl
2
How many amino acid transport systems dont require the use of Na
2
Di and tripeptides are transported into enterocytes by what protein? What ion does it require?
PepT1 requiring H+
Malabsorption can be classified into what three categories?
selective, partial and total
What are the four types of diarrhea?
secretory, osmotic, malabsorptive and exudative
which two types of diarrhea persist during fasting?
secretory and exudative
which type of diarrhea is characterized by isotonic stool and persists during fasting?
secretory
Which type of diarrhoea is due to excessive osmotic forces exerted by unabsorbed luminal solutes
osmotic diarrhea
What type of diarrhea is due to inflammatory disease and is characterised by purulent bloody stiils that continue during fasting?
Exudative diarrhea
What type of diarrhea follows generalized failures of nutrient absorption, is associated with steatorrhea and is relieved by fasting
Malabsorptive diarrhea
What proportion of ingested alcohol is metabolized
90%
What two things can be elevated in excessive alcohol intake?
y glutaml transpeptidase and mean corpuscular volume
Availability of what limits the rate of ethanol oxidation?
NAD+
What are the first two compounds that ethanol is oxidised to form?
acetaldehyde then acetic acid
What is the role of alcohol dehydrogenase where is it found?
It oxidises ethanol while at the same time reducing NAD+ to NADH it is found mainly in liver cells
What accounts for the build up of fat in the liver of alcoholics?
NAD is required for fatty acid oxidation and the conversion of lactic acid to pyruvate alcohol increases the NADH/NAD ratio and stops the liver being able to process fat
Excess acetaldehyde can cause what symptoms?
flushing, tachycardia, hyperventillation and distress/panic
At what time after alcohol withdrawal will delirium tremens begin?
48-72 hours
What is the role of Chlordiazpoxide/Librium in the treatment of alcoholism how is it administered?
It helps to stop withdrawl and is given in a reducing dose
What is the role of acamprostate and naltrexone in the treatment of alcohol withdrawal? how is it administered?
It reduced the urge to drink and is given in a fixed dose for 6-12 months
What are the three stages of pancreatitis?
activation, inflammation and damage to the pancreas, inflammation and damage elsewhere
What are the four main causes of inappropriate trypsin activation?
Pancreatic duct obstruction, marked elevation of intracellular calcium, primary acinar cell injury or defective intracellular transport
What two serum enzymes are raised in pancreatitis?
serum amylase and lipase
Markedly elevated serum levels of lactic dehydrogenase indicate what in pancreatitis?
poor prognosis
