lecture 19/20 Flashcards
liver, pancreas
function of the liver
general list
- endocrine secretion
- exocrine secretion
- inactivation of substances
- conversion of substances
- hemopoeisis
- storgae of substances
what does the liver secrete (endocrine)
somatomedin, albumin, fibrinogen, prothrombin, transferrin, VLDL
what does the liver secrete (exocrine)
bile acids, bilirubin, phospholipids/cholesterol
what are some examples of the inactivations/elimination done by the liver?
- glucuronly transferase conjugates glucuronic acid to bilirubin but also to barbituates, antihistamines, anticonvulsants, insecticides, etc.
- endocytosis od hormones and cholesterol (LDL particles)
an example of a conversion done in the liver
T4 (thyroxine) to T3, which is more potent
what substances does the liver store?
glycogen and lipids
what is the space between the endothelial cells and the hepatocytes called?
space of disse
what is present in the portal space?
- hepatic arteriole
- portal venule
- cholangiole
- bile duct
what structure provides stability to the hepatocytes?
reticular fibers
role of the sER in the hepatocyte
- store long-chain fatty acids, triglycerols, phospholipids, and cholesterol
- synthesize bile
role of the rER in the hepatocyte
synthesize apolipopoteins
role of the peroxisome in hepatocytes
- catalase that converts hydrogen peroxide (byproduct of b-oxidation) into water and oxygen
- b-oxidation of long fatty acids
- catabolsim of ETOH
- break down pruines to uric acid
- cholesterol synthesis
where are tight junctions located in the liver and why?
above and below the bile canaliculus so nothing escapes
what is contained in bile and how is it synthesized?
taurocholic acid = tauine + cholesterol
glycocholic acid = cholesterol + glycine
bilirubin conjugated to glucuronic acid
direction of blood and bile flow in a helaptic lubule
blood from both hepatic arteriole and prtal vein go toward the central vein
bile goes from the bile canaliculi to the cholangiole/bile duct
what is the difference between a classic lobule, portal lobule, and hepatic acinus
- classic: central vein in the middle with many portal spaces around (“natural” deliniation via CT)
- portal lobule: portal space in the middle and 3 central veins make the corners
- hepatic acinus: oval around 2 portal spaces and 2 central veins
turnover of hepatocytes
150 days
can the liver regenerate when damaged?
yes, normally it can but when it has undergon repeated damage, CT proliferates, cauing cirrhosis
is the pancrease an endocrine or exocrine gland? explain.
a combination of both:
* endo: islet of langerhans
* exo: compound acinar gland (similar to parotid)
what is the embryonic origin of the oancreas and salivary glands?
from envaginations of the endodermal lining of the embryonic intestine
what does the exocrine pancreas make?
a slightly alkaline fluid and proteins consisting of more enzymes and pro=emzymes capable of digesting the main components of ingested food in the small intestine
how does the endocrine pancreas form?
some cells from the developing acinus detach and further differentiate to form the islet of langerhans
what is the shape of the pancreas gland?
compound acinar gland
the pancreas is surrounded by ___________
a capsule of CT
what surrounds the islet of langerhans?
thin capsule of CT and reticular fibers
what type of interlobular duct is found in the pancreas?
intercalated duct only
pancreatic acini contain what granules?
zymogenic
centro-acinar cells are derived from ________
intercalated duct that goes into the serous acinus
what do zympgenic granules contain?
proenzymes:
* trysinogen -> trypsin
* pro-carboxypeptidase -> carboxypeptidase
* pro-elastase -> elastase
* pro-phospholipase A -> phsopholipase A
active enzymes:
* lipase
* amylase
* RNAse
* DNAse
how is glucagon produced?
synthesized as proglucagon and cleaved in the a-cells of the islet of langerhans, where the final product is 29 AAs
proglucagon can also be converted to what? and where does this occur?
other than glucagon
into glucogon-like peptides, when it is expressed in the intestinal tract and processed there
function/effect of glucagon
- maintain normal concentration of glucose in the blood (opposite effect of insulin)
- so, increase concentration
- atimulates breakdown of glycogen stored in the liver and/or activate hepatic gluconeogenesis
which type of capillaries are found in the islet of langerhans?
fenestrated capillaries
what cell types are found in the islet of langerhans? what are their general abundance, location, hormone produced and function
- a-cell: 15-20%, periphery, glucagon, glycogen breakdown/gluconeogenesis
- b-cell: 70%, central, insulin, uptake of glucose.lower glucemia
- delta-cell: 5%, everywhere, somatstatin, inhibit release of glucagon&insulin/HCL secretion via parietal cells
- PP cells: 1%, everywhere, pancreastic polypeptide, stimulate activity of cheif cells
what causes acute pancreatitis?
chronic alcohol ingestion b/c cause obstruction of the duct system and activation of trypsin or release of enzyme into the intercelullar space
what causes type 1 diabetes?
auto-immune disorder causing destruction of B-cells
