Alimentary Systems 2 - Liver Flashcards Preview

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Flashcards in Alimentary Systems 2 - Liver Deck (28)
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1
Q

Where is the liver located?

A
  • Behind the ribcage, but below the diaphragm
  • Mainly on the right of the body
  • Also in the upper left quartile
2
Q

Describe the basic gross anatomy of the anterior liver surface

A
  • Right lobe is the largest, left lobe is smaller. These are the only lobes visible in an anterior view
  • Right and left separated by the falciform ligament, which becomes the ligamentum teres
  • Coronary ligament above the right lobe
  • Left triangular ligament above the left lobe
3
Q

Describe the basic gross anatomy of the posterior liver surface

A
  • Caudate lobe can be seen between the left and the right lobe, superior
  • Quadrate lobe can be seen between the right and left lobe, inferior
  • Gallbladder is seen between the quadrate love and the right lobe
  • IVC and left hepatic vein at the top
4
Q

Describe the couinaud classification

A
  • 8 functionally independent segments, labelled in a clockwise direction (1-8)
  • Centrally there is the portal vein, hepatic artery and bile duct
  • Peripherally hepatic vein
5
Q

Describe the blood supply of the liver

A
  • Rich blood supply (25% of resting cardiac output)
  • Dual blood supply (20% arterial from hepatic artery left/right)
  • Hepatic portal vein (80%venous blood)
  • Drains into the inferior vena cava
6
Q

What is the purpose of the dual blood supply?

A
  • Hepatic portal vein (nutrients from the stomach are delivered to be processed)
  • Hepatic artery (delivers oxygenated blood)
7
Q

How is the liver divided morphologically?

A
  • Lobules
  • A lobule contains a portal tract/triad containing the branch of the hepatic portal vein, hepatic artery, and a bile duct.
  • 6 triads in one lobule
  • Interlobular veins in the centre drain to hepatic vein
  • Bile drains the opposite direction to blood (blood to centre, bile to triad)
8
Q

Describe the functional division of the liver?

A
  • Acinis
  • Blood flow (diamond shape joining two interlobular veins)
  • Bile flow (from centre to portal tract via canaliculus)
  • Zone 3 is furthest from the portal tract
  • Zone 1 is closed to the portal tract
  • Zone 2 is in the middle
9
Q

List the functions of the liver

A
  • Bodys kitchen
  • Biosynthesis
  • Digestion
  • Energy/metabolism
  • Degradation
  • Detoxification
10
Q

List the cell types in the liver and their proportion/location.

A
  • 80% of the cells are hepatocytes
  • Endothelial cells line blood vessels and sinusoids
  • Cholangiocytes line biliary structures
  • Kupffer cells are phagocytes in the sinusoid
  • Hepatic stellate cells store vitamin A, and are activated to be fibrogenic
11
Q

Compare the structure of hepatocytes, hepatic stellate cells and kupffer cells

A
  • Flattened, dense cell nuclei in the sinusoid may be Kupffer cells or stellate cells
  • Hepatocytes are large with pale and rounded nuclei
12
Q

Describe the arrangement of hepatocytes

A

Radiate from a central vein in sheets (cords)

13
Q

Describe the function of sinusoidal endothelial cells

A
  • Fenestrated

- Allows lipid and other large molecules to move to and from hepatocytes

14
Q

List the functions of kupffer cells

A
  • Phagocytosis

- Secretion of cytokines that promote HSC activation

15
Q

How long does it take for stored liver glycogen to be used up?

A

It will be used in a 24 hour fast

16
Q

How is glucose made in the liver?

A
  • Pyruvate is converted to glucose by gluconeogenesis requiring 6ATP
  • Glycogenolysis also occurs
17
Q

How are proteins processed by the liver?

A
  • Amino acids from the diet are converted to proteins in the liver
  • Transamination can also occur, which converts non-essential amino acids to essential amino acids
  • Deamination occurs to make urea which can be excreted in urine, leaving the carbon skeleton for glucose synthesis
18
Q

List the conversions in transamination

A
  • a-ketoglutarate to glutamate, proline or arginine
  • Pyruvate to alanine, valine or leucine
  • Oxaloacetate to aspartate, methionine, lycine
19
Q

Describe the process of deaminaton in the liver

A
  • Uses the glucose-alanine cycle
  • Pyruvate + glutamate converted to alanine in the muscle cell
  • Alanine travels to the liver where it is converted to glutamate again via a-ketoglutarate
  • NH2 is removed from glutamate using ATP
20
Q

What happens to fatty acids in the liver?

A
  • Fatty acids from adipose cells travel to the liver and enter beta-oxidation
  • Acetyl coA produced enters the TCA cycle
  • Metabolism of acetoacetate can also occur
21
Q

Describe the process of lipoprotein synthesis in the liver

A
  • Glucose is converted to glycerol
  • Converted to tri-acyl glycerol and apoproteins
  • Lipoproteins are picked up by VLDL, which take them to triglycerides
  • LDLs transport cholesterol to tissues
  • HDLs pick up excess cholesterol
22
Q

What is stored in the liver?

A
  • Fat soluble vitamins including vitamin ADEK

- Stores iron as ferritin for erythropoiesis

23
Q

How does detoxification occur in the liver?

A
  • P450 enzymes
  • First phase makes toxins more hydrophilic
  • Second phase attaches a water soluble side chain making it less reactive
24
Q

List the three functions of the liver

A
  • Detoxification and immunological functions
  • Metabolism and catabolism
  • Storage, excretory and secretory functions (bile secretion)
25
Q

Describe the biliary tree

A
  • Bile canaliculi
  • Small ductules, which in turn drain into small bile ducts.
  • Small bile ducts coalesce into larger bile ducts for each liver segment
  • These merge together to form the right and left hepatic ducts, which converge to form the common hepatic duct.
  • Connected to this duct is the cystic duct, which connects the gall bladder to the biliary tree.
  • The merging of the common hepatic duct and the cystic duct forms the common bile duct, which extends towards the duodenum. - The pancreatic duct joins and the vessel is then called the ampulla of Vater, which opens up into the medial wall of the duodenum at the duodenal papilla.
26
Q

List the functions of bile

A
  • Cholesterol homeostasis
  • Absorption and digesition
  • Toxin excretion
27
Q

Where is bile produced?

A
  • Hepatocytes produce 60% of bile

- Cholangiocytes produce 40% of bile

28
Q

What does the gall bladder do?

A
  • Stores bile
  • Acidifies bile
  • Concentrates bile, absorbing most of the water