Liver and Pancreas Flashcards
1
Q
liver functions
A
- gluconeogenesis
- detoxification
- storage
- produce plasma proteins
- bile production
- transfer of IgA into bile canaliculi
2
Q
gluconeogenesis
A
converts aa’s and lipids into glucose
3
Q
what detox does the liver do?
A
microsomal mixed-function oxidase enzyme system catalyzes methylation, oxidation, or conjugation of drugs, toxins, chemicals
4
Q
what is stored in the liver?
A
- glycogen
- triglycerides
- vitamin A
5
Q
what plasma proteins are produced in the liver?
A
- fibrinogen
- prothrombin
- albumin
- urea
- acute phase proteins
6
Q
endocrine vs. exocrine secretions of liver
A
endo: plasma proteins, acute phase proteins
exo: bile
7
Q
in what organelle is bile made?
A
sER
8
Q
describe liver circulation/blood supply
A
- afferent vessels: 20-30% hepatic artery, 70-80% portal vein
- efferent vessels: central vein
9
Q
what subdivides liver into lobes and lobules?
A
Glisson’s capsule - fibroconnective tissue capsule
10
Q
liver composition/cells
A
hepatocytes (parenchymal cells) arranged in anastamosing and branching plates
11
Q
contents of hepatocytes
A
- abundant rER and sER
- many lysosomes
- PEROXISOMES
- many mitochondria
- glycogen deposits
- lipid droplets
12
Q
classic liver lobule
A
hexagonal arrangement of hepatocyte plates around a central vein
13
Q
nucleus of liver cells
A
- can be binucleate w/ large nuclei
- can be polyploid
14
Q
do liver cells divide?
A
yes - if part of liver removed
15
Q
contents of portal canal
A
- portal vein
- hepatic artery
- bile duct
- sometimes lymphatics
16
Q
direction of blood flow vs. bile flow in liver
A
blood: from vessels in portal area through liver sinusoids to empty in central vein
bile: from liver cells out into bile duct in portal area
(opposite directions)
17
Q
sinusoids
A
discontinuous endothelial (large fenestrations) lined spaces located in b/w plates of hepatocytes
18
Q
Kupffer cells
A
fixed phagocytic cells in the monocyte lineage
19
Q
location of Kupffer cells
A
sinusoids
20
Q
subendothelial space b/w the hepatocytes and the sinusoid endothelium?
A
space of Disse
21
Q
portal lobule
A
- centered on a portal area
- defined by 3 adjacent central veins
- triangle defines flow of bile into bile duct
22
Q
hepatic acinus of Rappaport/ liver acinus
A
- centered on a portal area
- defined by 2 adjacent central veins
- defines metabolic gradient from periportal area to the drainage zone (3 zones)
23
Q
zone 1 of liver acinus
A
- high O2 area
- oxidative functions: cholesterol synthesis, gluconeogenesis, plasma proteins
24
Q
zone 2 of liver acinus
A
intermediate region
25
zone 3 of liver acinus
- low O2 area
- hepatocytes here involved in detox
- susceptible to hypoxia
26
functions of space of Disse
exchange materials b/w blood and hepatocytes
27
contents of space of Disse
- reticular fibers
- hepatic stellate cells/ ells of Ito (fat storing)
- microvilli of hepatocytes
28
function of hepatic stellate cells
- vitamin A storage and metabolism
| - produces collagen during disease in response to cytokines from Kupffer cells in space of Disse
29
bile canaliculi
intercellular spaces b/w the hepatocytes
30
pathway of bile flow
secreted by hepatocytes -> bile canaliculi -> cholangioles -> canals of Hering -> bile ducts in portal areas -> hepatic duct -> cystic duct
31
canals of Hering
small bile ductules at the edge of liver lobules
32
functions of bile
- excretion of cholesterol, phospholipids, bile salts, conjugated bilirubin, electrolytes
- absorption of fat and fat soluble vitamins
- IgA transport to intestine
- excretion of drugs and heavy metals
33
reabsorption of bile
90% recirculated - reabsorbed in ileum -> venous blood from ileum -> portal vein -> liver sinusoids -> hepatocytes extract bile acids -> transported across hepatocytes -> resecreted into canaliculi
34
pathway of IgA production to secretion
plasma cells in intestinal mucosa -> enters circulatory system and goes to liver -> IgA complexed w/ secretory component -> released into bile
35
how are bile components transported into canaliculi?
ATPases in plasma membrane
36
MDR1 and MDR2
multidrug resistance transporters
- MDR1: transports cholesterol
- MDR2: transports phospholipids
37
MOAT
multispecific organ anionic transporter - transports glutathione conjugates
38
BAT
biliary acid transporter - transports bile salts
39
what does a genetic defect in MDR2 cause?
focal hepatic necrosis and bile ductule proliferation
40
function of spleen macrophages
removal of old RBCs
41
what happens to the heme from digested RBCs?
converted to bilirubin -> released in blood -> conjugated w/ albumin -> enters hepatocyte -> complexed to ligandin -> sER releases free bilirubin in cytosol -> glucoronic acid added to form conjugated bilirubin -> secreted into bile
42
hepatitis
inflammation of liver - commonly from viruses or toxic materials
43
hepA
- infectious
| - fecal oral route
44
hepB
- serum hepatitis
| - transferred by blood and blood products
45
hepC
- hepatocellular carcinoma
| - transfusion related
46
cirrhosis
degeneration and fibrosis - damaged hepatocytes
47
what can cause cirrhosis?
- poisoning
- chronic alcohol use
- bile duct obstruction
48
what often accompanies long term alcohol consumption?
steatosis - fatty liver
49
jaundice
- excess bilirubin in blood
| - bile pigment in skin and sclera of eye
50
what can cause jaundice?
- liver dysfunction
- obstructed bile passages
- excess RBC destruction (hemolytic jaundice)
51
CHF
increased central venous pressure causes liver to engorge w/ blood (enlarged)
52
portal hypertension
obstructed blood flow - leads to fluid accumulation in peritoneal cavity (ascites)
53
what is often associated with portal hypertension?
cirrhosis
54
what frequently obstructs bile outflow from liver?
pancreatic carcinoma
55
what can result in hyperbilirubinemia?
hemolytic disease such as erythroblastosis fetalis
56
erythroblastosis fetalis
blood group incompatibility b/w mother and fetus
57
why is free bilirubin bad?
toxic to brain
58
how is alcohol metabolized?
ADH or mixed-function oxidase (MFO)
59
what does the ADH system produce?
acetaldehyde and excess H+
60
what does the MFO system produce?
acetaldehyde and ROS - causes lipid peroxidation
61
how does chronic liver disease lead to fibrosis?
viral/alcohol/bacterial toxins -> proinflammatory cytokines released from Kupffer cells -> induces hepatic stellate cells to transform to myofibroblasts -> produce collagen
62
how does fibrosis affect the liver?
restricts portal venous blood flow
63
what is cholestasis and what causes it?
slow or stop of bile flow - caused by TNF-a
64
function of gallbladder
stores bile and releases it into duodenum
65
what causes the gallbladder to release it into duodenum?
cholecystokinin
66
lining of gallbladder mucosa
- simple columner epithelium
| - numerous microvilli on apical surface
67
lamina propria of gallbladder
loose CT that blends w/ "submucosa"
68
muscularis externa of gallbladder
thin fascicles of smooth muscle fibers
69
what is the key feature to identify gallbladder?
diverticula of epithelium - outpocketings of the mucosa that form what appear to be epithelial lined cysts in the lamina propria (Rokitansky-Aschoff sinuses)
70
adventitia and serosa of gallbladder
attached to liver: adventitia
| most covered by serosa
71
biliary calculi
gallstone concretions
72
what is usual composition of gallstones?
cholesterol crystals - can also be from calcium salt of bile (calcium bilirubinate)
73
where do you find gallstones?
gallbladder and bile duct
74
how is the pancreas subdivided?
gland enclosed in a CT capsule - subdivides into lobules via septa
75
endocrine vs. exocrine parts of pancreas
endo: islets of Langerhans
exo: digestive enzymes
76
what type of stain is used to distinguish the cell types in the islets of Langerhans?
Mallory-Azan stain
77
types of cells in islets of Langerhans and percent composition
- alpha/A cells (15-20%)
- beta/B cells (60-70%)
- delta/D cels (5%)
- epsilon cells (<1%)
- PP/F cells (10%)
78
A cell product
produce glucagon -> elevate blood glucose
79
B cell product
produce insulin -> decrease blood glucose
80
D cell product
produce somatostatin -> inhibits hormonal release of neighboring secretory cells
81
what color do D cells stain?
blue
82
epsilon cell product
produce ghrelin -> stimulates appetite
83
PP/F cell product
produce pancreatic polypeptie -> inhibits release of exocrine pancreatic secretions
84
arrangement/surroundings of endocrine cells of pancreas
- surrounded by reticular fiber network
| - located among acini of exocrine pancreas
85
exocrine pancreas secretions
- amylase, lipase, ribonuclease, deoxyribonuclease
- trypsin, chymotrypsin, carboxypeptidase
- enzyme poor alkaline fluid (bicarb)
86
what are amylase/lipase/ribonulease/deoxyribonuclease secreted in response to?
cholecystokinin from intestinal enteroendocrine cells
87
how are trypsin/chymotrypsin/carboxypeptidase secreted?
proenzyme form - must be activated in the intestine by more acidic environment
88
what secretes the bicarbonate and in response to what?
intercalated duct cells - in response to secretin produced by intestinal enteroendocrine cells
89
cells of intercalated ducts
centroacinar cells
90
epithelium of intralobular ducts
cuboidal
91
how can you identify interlobular ducts?
surrounded by large amount of CT
92
T1DM
insulin dependent
- sudden onset before age 20
- low levels of plasma insulin
- polydipsia, polyuria, polyphagia
93
T2DM
non-insulin dependent
- in overweight people over 40
- may be normal insulin levels or impaired insulin release
- decreased insulin receptors
- faulty post-receptor signaling
94
what is a significant component of insulin resistant diabetes?
muscle insulin resistance
95
HIS
hepatic insulin resistance - due to faulty signaling through docking molecules (insulin receptor substrate- IRS) proteins that connect insulin receptor activation to downstream kinase cascades such as the PI3K and MAPK pathways
96
what can also contribute to development of T2DM?
HIS
97
pancreatitis
inflammation of pancreas - often due to gallstones
98
acute necrotizing pancreatitis
proenzymes may be activated - digest pancreatic tissues
99
what can cause acute necrotizing pancreatitis?
- infection
- gallstones
- drugs
- trauma
