Accessory Digestive Organs Flashcards
____ and ____ Embryological outgrowths of primitive gut; Function as accessory digestive organs
Liver and pancreas
____ is largest gland & internal organ—divided into 4 lobes (L, R, caudate, & quadrate)
Liver
Detoxification of metabolic waste (e.g., deamination of AA’s urea)•Metabolism & detoxification of drugs & toxins (e.g., alcohol, abx)•Destruction of senescent rbc’s•Recycling of Hb via synthesis & secretion of bile•Synthesis of plasma proteins (clotting factors, albumin, lipoproteins)•Miscellaneous metabolic functions (e.g., glycogen synthesis & storage, gluconeogenesis) are the main functions of the _____
Liver
External surface of liver covered by a ____ called ______
connective tissue capsule; Glisson’s capsule
Monosaccharides & AA’s from digestion enter liver via ____; carries 75-80% of body’s deoxygenated blood to liver; also carries potentially toxic compounds absorbed from diet to liver to be conjugated or detoxified
hepatic portal V
Oxygenated blood supplied to liver by
hepatic A
hepatic A is a branch of
celiac trunk
hepatic A turn into _____ in hepatic lobules
portal Aa
Carries only ~20-25% of blood to liver; mixes with unoxygenated blood from portal V to perfuse liver cells
portal Aa
T/F: Liver is a nutrient rich, but O2 poor environment
True
Venous drainage of lobules via _____ which empties into ____
central Vv; hepatic V
liver cells are called
hepatocytes
Most _____ diploid, but some polyploid &/or binucleate
hepatocytes
Contain large #’s of cytoplasmic granules (rER & lysosomal products) & storage products
hepatocytes
Aging hepatocytes accumulate brown pigment called
lipofuscin
Individual hepatocytes polygonal, arranged in anastomosing _____
cords
Individual hepatocytes polygonal, arranged in anastomosing cords paralleled by ________
venous sinusoids
Sinusoids lined by ________ cells, a discontinuous endothelium, with gaps between endothelial cells
sinusoidal lining cells
Between sinusoidal lining cells & hepatocytes is ______ continuous with lymphatics
space of Disse(= perisinusoidal space)
Hepatic cords & sinusoids supported by ____ fibers
reticulin (type III collagen)
Within sinusoids & space of Disse are phagocytic _____
Kupffer cells (Mφ)
Occasional _____ between hepatocytes—fat-storing cells containing lipid droplets, used for Vit A & D storage
Ito cells
Cords of hepatocytes arranged in ____
lobules
Classic lobule is arranged based on _____
blood flow
Classic lobule—based on blood flow; roughly hexagonal, with ____ in middle of lobule
central V (= centrilobular V, terminal hepatic venule)
Outer margin of each lobule delimited by _____
thin, connective tissue septum
______ are located at each “corner”, contain portal A, V, L, & bile duct
Portal tracts/ triads
What do the portal tracts contain?
portal A, V, L and bile duct
Blood enters from _____, percolates through sinusoids of lobule, drains via _____
portal tracts; central V
triangular area; based on bile flow (opposite to blood flow)
Portal lobule
Portal lobule is based on _____
Bile flow
_____ has portal triad in center and central veins at corners
portal lobule
diamond–shaped region between neighboring central Vv
Acinus
In Acinus lobule organization, _____ located along longitudinal axis, with ______ at sides
Central Vv; portal tracts
Combines aspects of blood flow, oxygenation, metabolism & pathology
Acinus organization of liver lobules
T/F: Hepatocytes in different zones of acinus lobules have different metabolic environments
True
Zone of acinus lobule organization of liver closest to portal tract, receives mostoxygenated blood;also most susceptible to toxic injury
Zone 1—(perilobular zone = periportal)
Zone of acinus lobule organization of liver that is the intermediate zone
Zone 2
Zone of acinus lobule organization of liver furthest from portal tract, closest to central VReceives least oxygenated blood; most susceptible to ischemic injury
Zone 3—(centrolobular zone)
Liver functions in detoxification or metabolism of various drugs, toxins, metabolites (e.g., ethanol, pesticides, & carcinogens) via _______ , or ________
microsomal mixed function oxidase system of sER; peroxidases of peroxisomes (P450 system)
A common sequela to repeated insults or chronic disease is _____•Characterized by hepatic degeneration & necrosis, followed by fibrosis & nodular regeneration
cirrhosis
associated with cirrhosis (due to fibrosis, blockage of blood flow)
Portal hypertension
T/F: Liver has ability to regenerate
Liver has ability to regenerate
Is liver an endocrine or exocrine gland?
Both
____ (Endocrine/Exocrine) functions of _____ (organ) include Synthesis of plasma proteins (e.g., fibrinogen, urea, albumin, prothrombin)–Synthesis of glucose–Gluconeogenesis (from non-carbohydrate sources, e.g., AA’s & lipids)–Storage & release of glycogen, lipids & lipoproteins–Vit A & D storage
Endocrine; liver
Exocrine (secretory) function of liver is _____ synthesis
bile synthesis
___ is emulsifying agent, facilitates hydrolysis of lipids by pancreatic lipases
Bile
Adult human liver secretes ____ bile/ day
~1 liter
Bile flow from liver ↑ by hormones such as _____ from enteroendocrine (APUD) cells
secretin, CCK, & gastrin from enteroendocrine cells
Bile synthesized by _____ & secreted into network of ______
hepatocytes; bile canaliculi
Small canals between hepatocytes, formed by grooves in plasma membranes of adjacent cells
bile canaliculi
Direction of bile flow ______ to blood flow, from canaliculi, in series of progressively larger ducts
opposite
What ducts are seen in portal triads in liver?
Bile ducts
What ducts are larger and scattered throughout parenchyma?
Intrahepatic ducts
Bile eventually enters duodenum at ______ following period of storage & modification in ______
major duodenal papilla; gallbladder
Muscular sac located in depression along surface of liver•Used to store & concentrate bile; volume ~100 ml
Gallbladder
Gallbladder is lined by _____ epithelium with _____ used for resorption of water
simple columnar epithelium; apical microvilli
Gallbladder lacks what layer?
Muscularis mucosae
Lamina propria of gallbladder is highly folded with occasional ________
tubuloalveolar mucus glands
______ stimulates contraction of gallbladder
CCK (cholecystokinin)
Water, ions, electrolytes, cholesterol + phospholipids (= lecithin), bile acids (= bile salts) & bile pigments are the components of ____
bile
____is best known bile pigment—non-sol breakdown product of Hb
Bilirubin
water-soluble form of bilirubin, conjugated with glucuronide
Bilirubin glucuronide
Failure to absorb bilirubin or failure to conjugate it & secrete glucuronide => accumulation of bile pigments & ____
jaundice
Supersaturation of bile => ____ which are primarily cholesterol and calcium salts
gallstones (biliary calculi, cholelithiasis)
Obstruction of bile ducts (choledocolithiasis) =>____ or _____ if severe
bile stasis, or jaundice (icterus)
Chronic inflammation of gallbladder =>
cholecystitis
Following Sx, unable to concentrate bile; need to limit ingestion of ____
fats
Highly lobulated gland with thin, connective tissue capsule, located in bend of duodenum
Pancreas
Embryological outgrowth of primitive gut•Both exocrine & endocrine components—
Pancreas
Ductless endocrine pancreatic tissue located in ___
islets of Langerhans
Most of pancreas is _____ —a compound, acinar, serous gland•
exocrine (i.e., with ducts)
(Pancreas) Densely packed serous _____ contain pyramidal secretory cells surrounding a central lumen (duct)
acini
Acinar cells of pancreas contain ______ like trypsinogen, amylase, and lipase
zymogen granules (inactive enzyme precursors)
Trypsin & chymotrypsin are ____
proteases
amylase breaks down
carbohydrates
lipases digest ____
lipids
Trypsin, chymotrypsin, amylase, and lipases Empty into ____(add bicarbonate & water to pancreatic sections; neutralize acidic chyme from stomach => optimal pH for pancreatic enzymes)
intercalated ducts
Duct cells that form beginning of intercalated duct sometimes visible in center of acini, called _____
centro-acinar cells
Intercalated ducts empty into larger ____
intralobular ducts
intralobular ducts empty into larger _____
interlobular (=extralobular) ducts
Pancreatic secretions enter duodenum via ______ at ______
pancreatic duct at major duodenal papilla
Principle regulators of exocrine pancreas— _______
polypeptide hormones secreted by enteroendocrine (APUD) cells
secreted by “G” cells of pyloric stomach; stimulates secretion of pancreatic fluid
gastrin
secreted by “S” cells; stimulates secretion of bicarbonate by cells of intercalated ducts
secretin
secreted by “I” cells, stimulates acinar cells to secrete zymogens
CCK (cholecystokinin = pancreozymin)
converts trypsinogen trypsin (within small intestine), which converts chymotrypsinogen chymotrypsin (digests proteins)Cascade rxn prevents pancreas from digesting itself
enterokinase
autodigestion of pancreas brought on by alcoholism•Cascade rxn breaks down =>Premature conversion of chymotrypsinogen to chymotrypsin & autolysis•Severe, acute ____ can be fatal within hours
Pancreatitis