Pancreas Flashcards
whats unique about the pancreas in terms of glands?
it has an exocrine (main part, 98%) and endocrine portion
endocrine portion of pancreas is mostly located where?
in the tail of pancreas (to the left)
the gallbladder, liver and pancreas all have ducts that merge and enter what?
duodenum (1st part of small intestine)
which organ secretes and synthesizes bile? where is it concentrated?
liver, it then travels to gallbladder via hepatic ducts (or common bile ducts) for it to be concentrated).
what cells make up the endocrine system? exocrine? which is vascular which is avascular?
ilet of langerham make up endocrine and these are vascular (they have capillary system innervating it)
secretory acinis: avascular, blood supply is from surrounding CT
what is the heirarchial organization of cells in exocrine duct systems?
- centroacinar cells (type of squamous cell), top most cell forms smallest duct
- simple low cuboid (intercalated duct, 1-2 centrocinar cells merge)
- higher cuboid/low columnar (intralobular duct, several acini)
- stratified cuboid or columnar (interlobular collecting duct to main duct, has two layers)
what is unique about the first part of the intralobular duct?
it is striated due to basal infoldings to increase SA
how can you tell apart endocrine from exocrine pancreas in a image?
endocrine stains lighter, exocrine stains darker
how many cells per ilet?
100-1000 cells/ilet
what is the septum?
collagenous CT that carries blood supply to nonvascular cells.
what are the three principle cells in the ilets?
- alpha cells (secrete and synthesize glucagon)
- beta cells (secrete and synthesize insulin)
- D (delta) cells (secrete and synthesize somatostatin)
where are the three principle cells normally located in an ilet and what percent of each cell is normally present?
alpha (more toward periphery, dense core granules regular shape, 20-25%)
beta (60-80%, more in core, dense core granules are irregular dense core has insulin and Fe)
delta (5-10%, 2 forms 14 and 28 aa forms, inhibits insulin and glucagon release)
what other products do beta cells secrete?
C peptide, amylin and proinsulin
what is a fourth cell type in ilet but not very abundant? what are two other cell types present?
pancreatic polypeptide hormone (PP) 15%
G cells: synthesize gastrin, 1%
neurons (secrete VIP) and glial cells
capillaries present in ilets are of what type?
fenestrated, discontinuous, leaky.
insulin is made up of what two chains? the two chains are connected by what? what links are made between the two chains?
alpha: 21 AA
beta: 30 AA (main biological activity)
C peptide (this is cleaved in the golgi)
S-S links
what are the major targets of insulin? which cells have receptors?
liver, skeletal muscle and adipose.
all cells have receptors
processing of insulin starts where? what are the remaining steps?
at ribosome, preproinsulin is the first product from the ribosome. before it goes to the golgi for processing it becomes proinsulin, once C peptide (35AA) is cleaved it becomes mature insulin.
pork insulin differed from humans by what? which caused?
1-3 AA
immune response in some cases which was problematic.
glucose stimulates an increase in what intracellularly?
calcium and cAMP which causes secretory granules to line up and move to plasma membrane, once we get fusion of membranes, insulin is released.
what are the two major blood sources to the pancreas?
- celiac artery: supplies dorsal ancreas
2. superior mesenteric artery: supplies ventral pancreas
what are the two separate systems supplying blood to the pancreas?
- insuloacinar portal system supplies endocrine system then bathes exocrine system (it is a portal system therefore exception to the rule)
- acinar system supplies exocrine part only and is a regular system
what is unique about beta cells, what do they each have to be next too?
at least one capillary
what are the two types of diabetes? what do both types have in common?
- type 1: insulin dependent, destruction of beta cells, most prevalent type, usually in juvenilles
- type 2: insulin independent, insulin levels are normal or even higher but the target tissue receptors are not working, usually in obese people
both experience hyperglycaemia (excess of glucose in blood)
