Accessory Digestive Organs Flashcards
(106 cards)
1
Q
liver and pancreas are embryological outgrowths of
A
primitive gut
2
Q
liver and pancreas function as
A
accessory digestive orango
3
Q
— is largest gland & internal organ
A
Liver
4
Q
liver is divided into
A
4 lobes (L, R, caudate, & quadrate)
5
Q
Major functions of liver: (6)
A
- 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)
6
Q
External surface of liver covered by connective tissue capsule,
A
Glisson’s capsule
7
Q
Monosaccharides & AA’s from digestion enter liver via
A
hepatic portal V
8
Q
the hepatic portal vein carries –% of blood to liver
A
~75-80
9
Q
hepatic portal vein also carries potentially toxic compounds absorbed from diet to liver to be
A
conjugated or detoxified
10
Q
Oxygenatedblood supplied to liver by
A
hepatic A, a branch of celiac trunk
11
Q
hepatic A, a branch of celiac trunk goes to — — in hepatic lobules
A
portal artery
12
Q
portal artery carries only
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~20-25% of blood to liver
13
Q
portal artery mixes with
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unoxygenated blood from portal V to perfuse liver cells
14
Q
Liver is a — rich, but — poor environment
A
nutrient
O2
15
Q
Venous drainage of lobules via
A
central Vv
16
Q
central Vv leads to
A
hepatic V
17
Q
Liver cells are called
A
hepatocytes
18
Q
Most hepatocytes —, but
some are
A
diploid
polyploid &/or binucleate
19
Q
hepatocytes contain large #’s of
A
cytoplasmic
granules (rER & lysosomal
products) & storage products
20
Q
Aging hepatocytes accumulate
brown pigment,
A
lipofuscin
21
Q
Individual hepatocytes
polygonal, arranged in
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anastomosing cords
paralleled by venous
sinusoids
22
Q
Sinusoids lined by
A
sinusoidal
lining cells, a discontinuous
endothelium, with gaps
between endothelial cells
23
Q
Between sinusoidal lining
cells & hepatocytes is
A
space of Disse
24
Q
space of Disse
also known as
continuous with
A
perisinusoidal space
lymphatics
25
Hepatic cords & sinusoids
| supported by
reticulinfibers
| Type III collagen
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Within sinusoids & space of
| Disse are
phagocytic Kupffer
| cells (macrophages)
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Occasional --- cells between
| hepatocytes
Ito
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Ito cells
fat-storing cells
containing lipid droplets,
used for Vit A & D storage
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Cords of hepatocytes
| arranged in ---
lobules
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Classic lobule—
based on --- ---
roughly ---, with --- --- in middle of lobule
blood flow
hexagonal
central V
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SKIPPED
| central V in middle of lobule
centrilobular V,
| terminal hepatic venule
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Outer margin of each lobule
| delimited by thin,
connective
| tissue septum
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Portal tracts/ triads
located at each “corner”,
contain
portal A, V, L, &
| bile duct
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Blood enters from portal
tracts, percolates
through sinusoids of
lobule, drains via
central V
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Portal lobule—
triangular
area; based on bile flow
(opposite to blood flow)
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--- --- in center & --- --- at corners
Portal triad
| central Vv
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Acinus—
diamond–shaped region between neighboring central Vv
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Central Vv located
along longitudinal axis, with portal tracts at sides
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Combines aspects of (4)
blood flow, oxygenation, metabolism & pathology
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Acinus divided into
zones 1, 2, & 3
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Hepatocytes in different zones have different
metabolic environments
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Zone 1—
(perilobular zone= periportal)—closest to portal tract, receives mostoxygenated blood
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zone 1 is most susceptible to
toxic injury
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Zone 2—
(intermediate zone)
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Zone 3—
(centrolobular zone)—furthest from portal tract, closest to central V
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zone 3 receives...
least oxygenated blood
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zone 3 is most susceptible to
ischemic injury
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Liver functions in detoxification or metabolism of various
drugs, toxins, metabolites (e.g., ethanol, pesticides, & carcinogens) via microsomal mixed function oxidase system of sER, or peroxidases of peroxisomes (P450 system)
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A common sequela to repeated
| insults or chronic disease is
cirrhosis
50
Cirrhosis is characterized by (2), followed
| by (2)
hepatic degeneration & necrosis
| fibrosis & nodular regeneration
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Portal hypertension—associated
| with
cirrhosis (due to fibrosis,
| blockage of blood flow)
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Liver has ability to
regenerate
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Liver functions divided into (2)
exocrine & endocrine
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secretion of products via ducts
exocrine
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secretion of products without ducts; directly into bloodstream
endocrine
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Endocrinefunctions of liver— (5)
• 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 storag
57
Exocrine (secretory) function of liver
bile synthesis
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Bile is --- agent, facilitates
emulsifying
| hydrolysis of lipids by pancreatic lipases
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Adult human liver secretes -- liter bile/ day
~1
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Bile flow from liver increases by hormones such as (3)
secretin, CCK, & gastrin from enteroendocrine (APUD) cells
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Bilesynthesized by --- & secreted into network of --- ---
hepatocytes
| bile canaliculi
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Small canals between ---, formed by
hepatocytes
| grooves in plasma membranes of adjacent cells
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Direction of bile flow --- to blood flow, from ---, in series of ---- ---- ---
opposite
canaliculi
progressively larger ducts
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bile synthesis includes (2)
bile ducts (portal
triads) & larger intrahepatic
ducts (scattered throughout
parenchyma)
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Bile eventually enters
| duodenum at ---, following (2)
major duodenal papilla
| period of storage & modification in gallbladder
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Gallbladder
Muscular sac located in depression along surface of liver
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Gallbladder is used to store & concentrate ---; volume -- ml
bile
| ~100
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Gallbladder is lined by
simple columnar epithelium with apical microvilli
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simple columnar epithelium with apical microvilli of gallbladder is used for
resorption of water
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Gallbladder lacks a
muscularis mucosae
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Lamina propria highly folded with occasional
tubuloalveolar mucus glands
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CCK (cholecystokinin) stimulates
contraction of gallbladder
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Components of bile (6)
```
Water
ions
electrolytes
cholesterol + phospholipids (= lecithin)
bile acids (= bile salts)
bile pigments
```
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--- is best known bile pigment
Bilirubin
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Bilirubin
non-sol breakdown product of Hb
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Bilirubin glucuronide—
water-soluble form of bilirubin, conjugated with glucuronide
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Pathology: Failure to absorb bilirubin or failure to conjugate it & secrete glucuronide results in (2)
accumulation of bile pigments & jaundice
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Supersaturation of bile results in
gallstones (biliary calculi, cholelithiasis)
| 1’ cholesterol & calcium salts
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Obstruction of bile ducts (choledocolithiasis) results in (2)
bile stasis, or jaundice (icterus) if severe
80
Chronic inflammation
cholecystitis
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Sx removal of gallbladder is
cholecystectomy
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Following Sx, unable to --- ---; need to limit --- --- ---
concentrate bile
| ingestion of fats
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Pancreas (2)
Highly lobulated gland with thin, connective tissue capsule
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pancreas is located in the
bend of duodenum
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pancreas has both (2) components
endocrine
| exocrine
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Ductless endocrine pancreatic tissue located in
islets of Langerhans
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Most of pancreas is
exocrine(i.e.,
with ducts)—a compound, acinar,
serous gland
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Densely packed serous acini
| contain
pyramidal secretory cells
| surrounding a central lumen (duct)
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Acinar cells contain
```
zymogen granules (inactive enzyme
precursors)
```
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inactive zymogen examples (4)
trypsinogen(= protrypsin),
chymotrypsinogen(=prochymotrypsin),
amylase,
lipase
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Trypsin & chymotrypsin are ---; amylase breaks down --- & lipases digest ---
proteases
carbohydrates
lipids
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Empty into --- ---(add bicarbonate & water to pancreatic sections; neutralize acidic chyme from stomach => optimal pH for pancreatic enzymes)
intercalated ducts
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Duct cells that form beginning of intercalated duct sometimes visible in center of acini, called
centro-acinar cells
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Intercalated ducts empty into
| --- ----, which exit into
```
larger intralobularducts
larger interlobular (=extralobular) ducts
```
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Pancreatic secretions enter duodenum via
pancreatic ductat major duodenal papilla
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Principle regulators of exocrine pancreas—
polypeptide hormones secreted by enteroendocrine (APUD) cells
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1 secreted by stomach:
gastrin
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gastrin: secreted by “---” cells of pyloric stomach; stimulates secretion of --- ---
G
| pancreatic fluid
99
3 secreted by duodenum:
secretin
CCK
enterokinase
100
secretin—secreted by “---” cells; stimulates secretion of
S
| bicarbonate by cells of intercalated ducts
101
CCK (cholecystokinin=pancreozymin); secreted by “---” cells, stimulates acinar cells to secrete ---
I
| zymogens
102
enterokinase—
converts trypsinogen which forms trypsin (within small intestine), which converts chymotrypsinogen which forms chymotrypsin (digests proteins)
103
Cascade rxn prevents pancreas from
digesting itself
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Pancreatitis
autodigestion
of pancreas brought on by
alcoholism
105
Cascade rxn of Pancreatitis breaks down which results in
Premature conversion of chymotrypsinogen to
| chymotrypsin & autolysis
106
Pancreatitis is ---,
severe
| acute Pancreatitis can be fatal within hours
