10/1 Histology!!! Flashcards
what are the two important hormones produced by DNES cells in the duodenum
secretin, and cholecystokinin
Cellular mechanism of exocrine secretion where portion of cell pinches off (exmp. mammary gland)
Apocrine
cellular mech. of exocrine secretion where entire cell ruptures
Holocrine
mech of exocrine where exocytois of vesicles and membrane transport of salt and water (sweat and salivary glands)
Merocrine
secretion into the blood stream
endocrine secretion
small saclike smewhat spherical structure
acinar or alveolar
long, non sacklike organization of exocrine gland
tubular
an inactive enzyme precursor
zymogen
what are the exocrine portions of the pancreaus?
the pancreatic acinus cells that are in a round sac like structure around the intercalated duct and dump right into the ducts to go to the tralobular ducts to the main pancreatic duct etc.
The endocrine portions of the pancreaus
not associated with the ducts, and are little islands or Islet of langerhans cells
what is the histological structure of the pancreus?
Acinar cells around the ducts with light staining with big nucleus. centroacinar cells (CA) that are light staing cells all by themselfs in the tissue. Intercalated ducts, that are light staining regions without nucleus!
Store zymogens and enzymes in seretory granules: trypsinogen, chymotrypsinogen, carboxypeptidase, amylase, lipase, DNase, RNase
Pancreatic acinar cells
what do pancreatic acinar cells store?
Store zymogens and enzymes in seretory granules: trypsinogen, chymotrypsinogen, carboxypeptidase, amylase, lipase, DNase, RNase
how to stimulate secretion from pancreatic acinar cells
cholecystokinin CCK from DNES cells of the duodenum
what are the ducts from the acinar cells in the pancrius and what ducts do they lead to?
intercalated ducts in parenchyma and interlobular in stroma. (no striated ducts like in the salivatory glands
secrete HCO3- rich fluid to keep zymogen inactive by maintaining pH >7.5
centroacinar cells (the cells that start the ducts in the acinar cell region) and intercalated ducts
secretion is principally via an exchanger for keeping the pH high in the ducts of the pancreus what is the exchanger
a Cl- / HCO3- exhcanger
what regulates the Cl-/HCO3 exchanger in centroacinar cells
CFTR
what stimulates the Centroacinar cells (CA) and ducts?
secretin
what is the duct that goes through the connective tissue through the pancreus
Interlobular ducts
what are the cells that if lost would make the pancreus no longer an endocrine pancreas?
islets of langerhans
what gives the islet of langerhans cells the ability to act as an endocrine cell
the presence of lots of fenestrated capillaries
what is a fenestrated cappilary?
have pores or “windows” in them but not big holes like the sinusoid
what is the homone in alpha cells
glucagon
what is the homone in beta cells
insulin
what is the hormone secreted by delta cells?
somatostatin
inhibit alpha and beta cells
somatostatin
what are the % of different islet cells
30% Alpha / 65% Beta / 4% Delta
anything which leads to zymogens being activated in the pancreas leads to auto-digestion of pancreatic tissue, inflammation, and intense epigastric pain
Acute pancreatitis
cancer more common in females, 3% of all, and poor prognosis
pancreatic carcinomas
complex syndrome produced by disruption of insulin signaling, dysregulation of lipid and glucoes levels and serious pathology
Diabetes mellitus
the largest gland, involved in regulating blood composition
Liver
Synthesis in the liver
blood proteins: albumin, transferrin, fibrinogen, prothrombin, angiotensinogen, etc. (endocrine activity);;
lipids and lipoporteins: cholesteerol, fatty acids, LDL, VLDL
Storage in the liver
glucose as glycogen
lipids as fat droplets
vitamins, fat soluble
Liver modificaation reactions
oxidation and reducation by cytochrom p450 in SER
Conjugaton with glucuronic acid sulfate; methylation (Bilirubin to glucuronide and secreted into bile)
several kinds of hormones turned over
Liver elimination reactions:
release products back into the blood (leave via urine)
release products into bile, e.g. bilirubin (leave via intestines)
Lipid digestion:
bile salts are detergents that emulsify fats and facilitate lipase action (exocrine activity)
describe the general microstructure of the liver:
Portal triad: the hepatic artery, the portal vein, and the bile duct are surrounded by connective tissue, and the blood from the portal vein are sent down very porous sinusoids (capilaries) to the terminal hepatic venule (central vein). as the blood goes down it goes past plates of hepatocytes that are creating bile and pushing it back the other way to the bile ducts.
what is a kupffer cell?
a macrophage resident in the liver to act on any pathogens coming from the GI system
the liver Acinus model describes 3 zones, what changes as you move from zone to zone what are the zones and what do they do?
these are the zones through the hepatic sinusoid where zone 1 has freshest blood, biggest mitochondria, most active glucuronidation, most active endocytosis, most lysosomes (metal deposits) highest regenerative activity!.
Zone three you do the oxidation/reduciton reactions (most P450), and Fat deposited here most
Zone 2 is intermediate!
why would the acinus model of the liver be useful for clinician
gives an ability to classify damage by location and guesse what type of damage is taking place and what might be the progression of the disease
the histology of the liver
Portal triad surrounded by alot of hepatocyts, and then an associated terminal hepatic vein, but no nice structure!
how do we prevent bile from leaking into the liver and damaging hepatocytes?
terminal bars around the cells of the bile duct create tight junctions!
how can we identify bile duct/ hepatic artery/ and portal vein
BD: terminal bars around a lumen (light cells)
HA: muscular smooth muscle cells surrounding a lumen
Pv: the squished snake lumen with association of the other two
how can we identify the hepatic venule?
a large lumen with no other associated vein or artery or ducts
describe the structure of the hepatocytes
they have tight junctions supported by desmosomes, with bile ducts between the cells, below they have microvilli, then space of disse and then the endothelium with lots of pores between to allow lots of exchange
what is the space between the hepatocytes where blood flows?
sinusoids
the opening between hepatic cells that carry bile
bile canaliculus
the cells the can acutally cull the blood cells if the spleen is removed
Kepffer cells
Store fat and fat soluble vitamins (like A and retinol)
Hepatic stellate cells, lipocytes, fat cells, cells of Ito, Vitamin A cells, interstitual cells
where are the hepatic stellate cells?
in the space of Disse
what happens if you have liver damage to the hepatic stellate cells?
they can transform into myofibroblasts and synthesize collagen after liver damage
what could contribute to fibrosis of the liver (cellular component)
hepatic stellate cells synthesizing too much collagen and other extracellular molecules
what could lead to portal hypoertension (cellular component)
Hepatic stellate cells as myofibroblasts express smooth muscle actin and can contract!
what could lead to dysregulation of retinol metabolism
reductinon in lipid storage in hepatic stellate cells
looks like little black dots inbetween hepatic cells
bile canaliculi
what does the gall bladder epithelium do?
sodium and water recovery, and bile concentration.
basolateral Na,K-ATPase to do this
bile is recyled in this type of recirculation
interohepatic recirculation
what else would follow the enterohepatic recirculation besides bile?
anything that has affinity for both fat and water
stimulates bile flow and induces contracaion of gall bladder, and relax the hepatopancreatic sphincter in the duodenum
CCK
causes bile ducts to secrete bicarbonate into bile
secretin
gall bladder inflammation
cholecystitis
inflammation of the liver
hepatits
prolonged serious inflammation, destruction of hepatocytes, and activation of myofibroblasts from stellate cells lead to excess collagen and this is called:
fibrosis
extensive fibrosis and disorganized regeneration leads to general dysfunction
cirrhosis
what happens in cirrhosis
blood flow decreases, impairing addition and removal of blood components
lack of flow produces portal hypertenstion, backpressure in venous system and asites (fluid in abdomen etc.)
blockage of bile flow:
cholestasis
what is cholestais do?
bile is a detergent that can dissolve cells, leading to serious liver damage
what if bile leaks into the blood?
yellow the skin etc. to create jaundice
what are some special functions of duodenum?
absorptive colomnar cells;
Enteroendocrine (DNES) cells;
Brunner’s Glands;
what do the absorptive columnar cells in duodenum do?
enterocytes produce enterokinase, which activates trypsinogen
and secrete HCO3- to protect agains acid coming form the stomach
what do the DNES cells make?
secretin and CCK
what about brunners glands?
found in the sumbucosa of duodenum, produce mucus to protect the duodenum surface.
Secretion onto a free surface (usually, but not always via a duct)
Exocrine
Types of glands that can be associated with a duct
simple tubular or acinar;
branched acinar
compound tubular or acinar
compound tubuloacinar gland
