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gastrointestinal > Liver > Flashcards

Liver Flashcards

1
Q

Where does the falciform ligament attach?

A

Anterior liver to the abdominal wall; separated by left and right lobes.

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2
Q

What does the coronary ligaments attach?

A

Superior liver to diaphragm

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3
Q

Which ligaments attach the liver to the duodenum and stomach?

A

Lesser omentum
Hepatoduodenal
Hepatogastric

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4
Q

What does the hepatic portal vein do?

A

Takes blood from the GI tract to the liver for processing, before returning blood to systemic circulation

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5
Q

Which veins drain into the hepatic portal vein?

What organs do they carry blood from?

A 
Superior mesenteric vein(small intestine)
Splenic vein (short gastric, gastroepiploic, inferior mesenteric and pancreatic veins).
Right and left gastric veins (stomach and oesophagus)
Superior pancreaticoduodeal veins (pancreas and duodenum)
Cystic vein (gallbladder and paraumbilical veins)
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6
Q

What are porto-systemic anastomoses?

Why are they important?

A

Anastomoses between portal and systemic circulation.

Allow blood to be shunted into the systemic system to bypass the liver, e.g. in portal hypertension.

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7
Q

What veins combine to form the hepatic portal vein?

A

Superior mesenteric and splenic vein.
Runs upwards, lies behind the common bile duct and hepatic artery, and anterior to the IVC. Penetrates the right border of the lesser omentum, and runs anterior to the epiploic foramen until it gets to the porta hepatis.

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8
Q

What is the structural unit of the liver?

A

Hepatic lobules

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9
Q

What are sinusoids?

A

Low pressure vascular channels receiving blood from the terminal branches of the hepatic artery and the portal vein at the periphery of lobules, which is then delivered to a central vein.

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10
Q

What is the functional unit of the liver?

A

Hepatic acinus

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11
Q

What composes the hepatic acinus?

A

Ellipsoidal mass of hepatocytes arranged around the hepatic arterioles and portal venules, just as they anastomose into sinusoids.

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12
Q

What is the sinusoidal epithelium like?

A

Fenestrated, to allow unimpeded flow of plasma from blood into the space of Disse.

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13
Q

What is the space of Disse?

A

Space between the hepatocytes and the sinusoidal epithelium; plasma collects here and flows back toward the portal tracts to collect in the lymphatics.

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14
Q

What are Kupffer cells?

A

Phagocytic cells in the hepatic sinusoids

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15
Q

What are stellate cells?

A

Pericytes in the space of Disse, involved in liver fibrosis. They store vitamin A and will proliferate and contract in liver damage

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16
Q

How does the liver regenerate?

A

Can lose up to 70% mass and still regenerate in 5-7 days; hepatocyte hyperplasia when needed.
Hepatocyte growth factor is important in promoting hyperplasia, as well as TNF, EGF and IL6 for regeneration.
TGF-beta inhibits liver cell proliferation.

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17
Q

What are the main functions of the liver?

A 
Filtration and storage of blood
Metabolism of carbs, fat, protein, hormones and foreign chemicals
Storage site for vitamins
Coagulation factor synthesis
Detoxification 
Bile formation and bilirubin metabolism.
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18
Q

How does the liver act as a reservoir of blood?

A

The liver usually holds 450ml of blood but this can increase by 0.5-1L if high pressure in the RA causes backflow of blood, which is then stored in hepatic veins and sinuses.

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19
Q

How does the liver ‘clean’ blood?

A

The hepatic macrophage system means bacteria in intestinal blood is phagocytosed by Kupffer cells as blood passes through sinuses.

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20
Q

What vitamins are stored in the liver?

A

Vitamin A: stellate cells, 10 month supply
Vitamin D: 3-4 month supply
Vitamin B12: 12+ month supply
Iron: stored in the liver as ferritin

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21
Q

What coagulation factors are made in the liver?

A

Fibrinogen
Prothrombin
Factor VII
Vitamin K

22
Q

What is bilirubin?

A

A bile pigment which gives urine and faeces their colour; a product of RBC breakdown.

23
Q

What is portal hypertension?

A

An increase in blood in the portal vein, which increases the blood pressure.

24
Q

What causes PTN?

A

Prehepatic causes: splenomegaly, portal vein thrombosis, obstruction of portal vein to the liver.

Intrahepatic causes: cirrhosis, primary sclerosing cholangitis, chronic pancreatitis, primary biliary cholangitis, schistosomiasis

Posthepatic causes: IVC obstruction, right HF.

25
Q

What is primary sclerosing cholangitis?

A

A disease of the bile ducts that causes inflammation and obliterative fibrosis of bile ducts inside and/or outside the liver.

26
Q

What is primary biliary cholangitis?

A

an autoimmune disease of the liver. It results from a slow, progressive destruction of the small bile ducts of the liver, causing bile and other toxins to build up in the liver: cholestasis

27
Q

What are the signs and symptoms of PTN?

A

Ascites (high pressure causes fluid to transude into lymph and leak into outer surface of the liver)
Splenomegaly (signs of anaemia, low platelet count, palpable)
Oesophageal varices (vomiting blood)
Caput medusa
Haemorrhoids

28
Q

What kind of imaging is useful in diagnosis?

A

Doppler ultrasonography: can find direction and velocity of portal blood flow, as well as splenomegaly, portal vein dilation and thrombotic occlusion.

29
Q

How can bleeding varices be treated in those with PTN?

A

Drugs:
Propanolol: used for prevention of bleeding and for previous bleeds.
Glypressin/octreotide: injections.

Endoscopic:
Banding: vein is sucked up by endoscope and a band is placed at the base of varix to form a clot.
Injection scleropathy: sclerosant injected into oesophageal veins to cause clotting/scarring.

Surgical:
Shunting: transjugular intrahepatic portal systemic shunt; blood shunted from portal vein into hepatic, but can lead to encephalopathy due to lack of toxins being removed.

30
Q

What are the different acinar zones of the liver?

A

1= closest to afferent arteriole; highest oxygen concentration; respiration, gluconeogenesis, bile production.
2=intermediate
3-closest to efferent arteriole; lowest oxygen concentration; glycolysis, lipolysis, drug metabolism, xenobiotic.

31
Q

What are the 2 main functions of the biliary system?

A

1) Fat digestion and absorption; bile acids emulsify food particles so pancreatic juice can get to the surface
2) Excretion of waste products from blood e.g. bilirubin and excess cholesterol

32
Q

How is bile secreted?

A

By hepatocytes, into the bile canaliculi, interlobular septa, terminal bile ducts and then into the duodenum or into the gallbladder via the cystic duct for storage.

33
Q

What effect does CCK have?

A

Stimulates gallbladder contraction and sphincter of Oddi relaxation.

34
Q

What effect does secretin have?

A

Stimulates bile secretion containing bicarbonate to help neutralise duodenal chyme.

35
Q

What are the components of bile?

A 
Bile salts
Bile pigments (bilirubin)
Cholesterol
Bicarbonate
Phospholipids
36
Q

What are the 2 bile salts?

A

Sodium glycocholate and sodium taurochlorate

37
Q

How much bile can the gallbladder store?

A

30-60ml

38
Q

How does the gallbladder concentrate bile?

A

Water and electrolytes are constantly absorbed into the mucosa, by active Na transport and secondary absorption of Cl and water. Concentrates bile up to 20x.

39
Q

How are bile acids recycled?

A

Cholesterol is converted to primary bile acids, which are conjugated with glycine or choline and then exported via the biliary tree into the lumen.
Bile acids are then metabolised by intestinal bacteria, and 95% are reabsorbed via the portal vein.
Hepatocytes then take up bile salts from the blood and then secrete them into the bile canaliculi.
5% of bile acids are lost in stool.

40
Q

What are primary and secondary bile acids?

A 
Primary= cholic and chenodeoxycholic acid
Secondary= metabolism of primary bile acids after hydrolysis by GIT flora. Absorbed in terminal ileum.
41
Q

What is bilirubin?

A

A yellow/orange bile pigment which is an end-product of haemoglobin degradation, and which gives urine and faeces their colour.

42
Q

What are the breakdown products of haemoglobin, following haemolysis by the reticuloendothelial system?

A

Globins: broken into amino acids and recycled
Iron: binds to transferrin and stored in liver as ferritin
Porphyrin ring: becomes bilirubin

43
Q

Where are macrophages of the reticuloendothelial system found?

A

Spleen, bone marrow, liver

44
Q

What are the components of micelles?

A

Bile salts, fatty acids, monoglycerides, phospholipids, cholesterol and fat-soluble vitamins

45
Q

How does the sphincter of Oddi regulate bile secretion?

A

SOO is contracted in the interdigestive period, and increased pressure in the common bile duct causes bile to flow back up into the gallbladder for storage (30-60ml)

46
Q

What do fatty acids and amino acids entering the duodenum after a meal cause?

A

Endocrine cells release CCK, causing gallbladder contraction and SOO relaxation so bile is released

47
Q

What does acidic chyme entering the duodenum after a meal cause?

A

S sells release secretion which causes bicarbonate release by duct cells of the liver into bile and bile production

48
Q

What are normal levels of total and conjugated bilirubin in adults?

A 
Total = <21 micromol/L
Conjugated = < 7micromol/L
49
Q

What levels of bilirubin are needed to see jaundice in the sclera and in the skin?

A 
Sclera = 30micromol
Skin = 100micromol
50
Q

What is the hepatocellular pattern of LFTs?

A

ALT/AST > 150u/L
ALP < 200 u/L

Transaminase elevation indicated hepatocellular injury

51
Q

What is the cholestatic pattern of LFTs?

A

ALP > 180 u/L
ALT < 150u/L
GGT > 100u/L

ALP and GGT elevation indicate cholestasis

gastrointestinal (10 decks)

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