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BMS 460 > Hepatobiliary System > Flashcards

Hepatobiliary System Flashcards

1
Q

go over the hepatobiliary system anatomy on slide 40

A

PLZ FUTURE YOU IS BEGGING

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2
Q

in which two ways is the liver connected to the digestive tract?

A
  1. portal vein
  2. bile duct
    –> any impairment to portal circulation and biliary outflow has serious effects on the liver!
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3
Q

what are the three clinical diseases involving liver inflow and outflow that we looked at?

A
  1. congestive heart failure
  2. portal hypertension
  3. carcinoma of the pancreas
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4
Q

congestive heart failure and the liver

A
  • the inferior vena cava and hepatic veins do not have valves
  • in congestive heart failure, central venous pressure increases
  • this causes blood to pool, enlarging the liver
  • this impairs liver function
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5
Q

portal hypertension

A
  • cirrhosis causes an obstruction to blood flow in the liver
  • cirrhosis also impairs the ability of hepatocytes to produce plasma proteins
  • the above factors result in portal hypertension, which increases the hydrostatic pressure in the portal vein and its intraheptic branches
  • this causes fluid to leak out into the peritoneal (abdominal) cavity: ascites
  • this loss of fluid is made worse because cirrhosis impairs the ability of hepatocytes to secrete proteins (albumin). this decreases plasma oncotic pressure, so fluid doesn’t want to flow into portal vein where albumin concentration is low
  • causes splenomegaly (pressure builds up in vessels) and ascites
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6
Q

carcinoma of the pancreas

A
  • carcinoma in the head of the pancreas obstructs biliary outflow by compressing common bile duct
  • about 60% of pancreatic tumors are carcinomas in the head of the pancreas
  • obstruction of the bile ducts causes jaundice
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7
Q

describe the liver overall

A
  • an encapsulated, self-contained organ
  • loosely attached to adjacent organs
  • part of the digestive tract, to which it is connected by portal veins and bile ducts
  • performs more than 100 functions in the body
  • center of the metabolic universe
  • ultimate toxic dump
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8
Q

liver and bilirubin

A
  • liver is essential for uptake, procesing, and excretion of bilirubin released from aged rbc’s
  • liver problems can lead to hyperbilirubinemia (in fact, this is the most common manifestation of liver disease)
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9
Q

the liver is a major source of…

A
  • plasma proteins
  • that is, all major plasma proteins except immunogobulins
  • makes albumin, coagulation factors, etc.
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10
Q

liver cells are rich in…

A
  • enzymes
  • these are released into circulation upon liver injury
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11
Q

what does liver do to drugs, hormones, and cytokines

A
  • removes them from circulation
  • metabolizes them
  • detoxifies
  • modifies them
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12
Q

how can viruses affect the liver?

A
  • certain viruses have exclusive tropism for the liver, meaning they specifically attack hepatocytes
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13
Q

can liver cells regenerate?

A

yes!!

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14
Q

liver and cancer?

A
  • liver can give rise to tumors
  • however, it is more often involved by tumor metastases
  • hepatocellular carcinoma is caused by hepatitis B virus, originates in hepatocytes
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15
Q

causes of liver failure include…

A
  • hepatitis, viral and non-viral
  • cirrhosis
  • liver cancer
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16
Q

two conditions that occur in liver failure

A
  • hepatorenal syndrome
  • hepatic encephalopathy
    (see curricular exercise for what these are)
    (note: these are both caused by cirrhosis, which is basically liver failure i think)
17
Q

the liver is the largest (what) in the human body

A
  • gland!
  • liver consists of four poorly defined lobes
  • it is surrounded by a collagen-elastic, fiber-containing capsule (of Glisson)
  • it is lined by peritoneum
18
Q

describe flow of blood through the liver

A
  • blood can enter the liver in one of two ways: hepatic portal vein or hepatic artery
  • hepatic portal vein brings blood with nutrients that have just been absorbed from food in the intestines
  • blood enters liver and travels through sinusoids to central vein in each lobule
  • central veins go to the inferior vena cava
  • hepatic artery brings arterial blood to the liver, blood goes through sinusoids and also ends up in the central veins that go to the inferior vena cava
  • note that the bile ducts, the third part of each portal triad, flows in the opposite direction (from central vein to bile duct in the triad at the corners of each lobule)
  • these bile ducts come together to form the common bile duct, which dumps into the duodenum
19
Q

what are three structures used to study liver architecture?

A
  • classic hepatic lobule (central vein at center)
  • portal hepatic lobule (portal triad at center)
  • hepatic acinus
20
Q

describe classic hepatic lobule model

A
  • single lobule is a hexagon with central vein and portal triad at each of the six points
  • each portal triad consists of a hepatic artery, portal vein, and bile duct
  • blood flows towards central vein
  • bile flows towards portal triad
21
Q

describe portal hepatic lobule

A
  • makes a triangle with central vein at each point
  • this connects three classic hepatic lobules
  • portal triad is at the center
  • shows how bile flows towards the center
22
Q

describe hepatic acinus

A
  • diamond shape
  • two opposite points are central veins in two separate classic lobules
  • other two opposite points are portal triads
  • shows zones of blood flow
23
Q

zone 1

A
  • closer to arterial center
  • highest oxygen saturation, nutrient levels, and metabolic activity
  • hepatocytes here are the first to begin the regenerative process after a partial hepatectomy
  • also first to get hit if there is a direct toxicant because they are right by arterial and portal venous blood supply
24
Q

zone 3

A
  • most susceptible to ischemia
  • first to undergo necrosis in systemic hypoxia
  • indirect toxicants mostly only damage zone 3 (indirect toxicants are substances that become toxic only after they are metabolized, for example carbon tetrachloride)
  • signs of bile flow obstruction first become evident in zone 3
  • bile kills these perivenular cels and causes formation of bile lakes
25
Q

three types of sinusoid-lining cells

A
  1. majority are endothelial cells with thin, fenestrated cytoplasms
  2. scattered are large, plump phagocytic cells called kupffer cells. these form part of the monocyte-macrophage defense system. with the spleen, they participate in removal of aged erythrocytes and other particulate debris from circulation
  3. stellate cells can’t be easily distinguished by light microscopy. they have dual function: vitamin A storage and production of extracellular matrix and collagen (also called perisinusoidal cells of ito or hepatic lipocytes)
26
Q

what is the space of disse

A
  • space outside of sinusoid where chylomicron remnants (lipoproteins) get processed and cirrhotic changes occur
  • it is the narrow space between the hepatocytes and the endothelial cells of the sinusoids
27
Q

biliary canaliculi

A
  • thin tubes in between hepatocytes that collect bile and transport it to bile ducts
  • they empty into progressively larger bile ducts, eventually becoming common bile duct that runs through the pancreas and deposits bile into the duodenum
  • they are on the apical sides of the hepatocytes
  • the basolateral sides face the sinusoids
28
Q

keys to understanding drug absorption

A
  • biochemical properties of a drug determine the best absorption route
  • optimal absorption of weak acids/bases depends on the pH or the GI tract of the surrounding environment
  • GI disease can affect the absorption of drugs
29
Q

first-pass effect

A
  • major mechanism that determines the ultimate concentration of a drug in the plasma
  • liver metabolizes and destroys lots of a drug administered orally (this is the first-pass effect) - this also encompasses effects of metabolism by the gut because gut flora and digestive enzymes also metabolize drugs administered orally
  • based on anatomy only, drugs absorbed beyond the oral cavity are transported to the liver via the portal vein, which results in less active metabolites in plasma
30
Q

why might a drug be administered sublingually or rectally?

A
  • these routes avoid first-pass metabolism in the liver
  • the lymphatic system also avoids first-pass metabolism, and is the only route of absorption from the small intestine that does this
31
Q

when to avoid giving drugs orally

A
  • if drug causes nausea/vomiting
  • if patient is vomiting currently
  • it patient is unwilling or can’t swallow pill
  • if drug is destroyed by digestive enzymes (insulin, for example)
  • if drug is not absorbed through the gastric mucosa (aminoglycosides, for example)
  • if drug is rapidly degraded (lidocaine, for example)
32
Q

drug route with rectal administration

A
  • into venous return from rectum
  • straight back to inferior vena cava and then heart
33
Q

drug route with sublingual administration

A
  • venous return from buccal cavity
  • straight into vena cava to heart
34
Q

drug route with oral (enteral) administration

A
  • into digestive tract
  • absorbed into portal circulation
  • to liver via portal vein
  • through liver, exit liver through hepatic vein
  • hepatic vein goes to ivc, then back to heart

BMS 460 (34 decks)

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