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Y1 GI > Physiology and pharmacology of the Liver > Flashcards

Physiology and pharmacology of the Liver Flashcards

1
Q

what is the metabolic hub of the body

A

The liver

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2
Q

the liver is the largest organ in the body true/false

A

true

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3
Q

what are the main regulatory functions of the liver

A

regulation of carbohydrate, lipid and amino acid metabolism

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4
Q

What is carbohydrate metabolism comprised of

A

GLUCONEOGENESIS - glucose produced from amino acids
GLYCOLYSIS - to form pyruvate thence lactate (anaerobic) , to acetyl co-A (aerobic)
GLYCOGENESIS- to store polymerised glucose as glycogen
GLYCOGENOLYSIS - to release glucose from glycogen as required

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5
Q

What is fat metabolism comprised of

A

processing of chylomicron remnants
synthesise of lipoproteins (eg. LDLs, HDLs, for export) and cholesterol (for steroid hormone and bile acid synthesis)
ketogenesis (in starvation)- important for neuronal function

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6
Q

What is protein metabolism comprised of

A

Synthesis of plasma proteins
Transamination and deamination of amino acids
Conversion of ammonia to urea via urea cycle

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7
Q

What hormones are deactivated in the liver

A

Insulin
Glucagon
Anti-diuretic hormone
Steroid hormones

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8
Q

What hormones are activated in the liver

A

Conversion of thyroid hormone to the more active triiodothyronine
Conversion of vitamin D to 25-hyfroxyvitamin D2 which is further converted in the kidney

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9
Q

What are the major functions of the liver

A

Storage of

  • Fat soluble vitamins A (Ito cells) DEK (in hepatocytes)
  • Water soluble vitamin B12 - long term storage of 3-5 years
  • Iron, copper
  • glycogen

Synthesis of proteins

Protection

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10
Q

What proteins are synthesised by the liver

A

-for metabolic processes of the organ
-for export
coagulation factors II, VII, IX, and X
Proteins C and S (involved in coagulation)
Albumin
Complement proteins
Apolipoprotiens
Carrier proteins eg. molecules which bind to hormones to keep them in solution

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11
Q

What are the protective functions of the liver

A

Kupffer cells (liver phagocytes) - digest/destroy particulate matter (bacteria) and senescent (old) erythrocytes

MORE- GET FROM SLIDES

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12
Q

What is the purpose of bile

A

participates in the digestion and absorption of fats and the excretion of products of metabolism
Incorporates otherwise insoluble fats into stabilised lipid droplets

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13
Q

Where is bile made/secreted from

A

Produced and secreted by hepatocytes and bile duct cells

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14
Q

Where is bile stored/concentrated

A

In the gall bladder
Removes water
Can cause solids to precipitate out (cholesterol) causing gall stones

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15
Q

What stops bile flowing from common bile duct to duodenum between meals

A

The closure of the sphincter of Oddi

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16
Q

What is bile released in response to

A

Enter of chyme into the duodenum -stimulates gall bladder smooth muscle to contract - VAGUS nerve also plays a role

17
Q

What is the pH of bile

A

Slightly Alkaline

Neutralises acidic chyme to create optimum pH for enzymes

18
Q

What does bile contain

A 
Primary bile acids 
Secondary bile acids 
Water and electrolytes 
Lipids and phospholipids 
Cholesterol 
IgA 
Bilirubin
19
Q

What are the primary bile acids

A

Cholic, and chenodeoxycholic acids

Converted by bacteria into secondary bile acids

20
Q

What are the secondary bile acids

A

Deoxycholic and lithocholic

Reabsorbed via portal system back to liver and resecreted back into bile

21
Q

How does the liver adapt when low in salts

A

Uses cholesterol to make more bile acids

22
Q

What is the most common pathology of the biliary tract

A

Cholelithiasis

23
Q

What is a gallstone

A

Crystalised cholesterol that over time grows into a gallstone

24
Q

What is the best treatment for symptomatic gallstones

A

Laproscopic cholecystectomy

25
Q

What happens to the majority of bile

A

Most is reabsorbed by active transport in the terminal ileum and undergoes enterohepatic recycling

26
Q

What are bile acid sequestrants

A

Promote the secretion of bile acids
Colveselam, Colestipol, colestyramine
Neither digested nor-absorbed by gut
Act by binding to bile acids, preventing their reabsorption

27
Q

Bile acid sequestrants increase the circulating fat levels true/false

A

FALSE

reduce circulating fat levels by lowering plasma LDL cholesterol

28
Q

What can bile acid sequesterants be used to treat

A

Hyperlipiddaemia (limited effect)
Cholestatic jaundice (itch)
Bile acid diarrhoea

29
Q

What enzyme mediate phase 1 of drug metabolism in the liver

A

Cytochrome P450s

30
Q

What does phase 1 of drug metabolism in the liver involve

A

Makes drugs more polar by
Oxidation
Reduction
Hydrolysis

31
Q

Why can’t lipophilic drugs be excreted, how do you make them more easily excreted

A

End up getting reabsorbed by kidney

Adding a polar aged to the lipohylic substance allows it to be excreted and not reabsorbed by the kidney

32
Q

What does phase 2 of drug metabolism in the liver involve

A

Conjugation

Adds an endogenous group on increasing polarity

33
Q

Example of a drug which is activated in the liver

A

Codeine which is activated to morphine in the liver

34
Q

Which phase of liver metabolism is anabolic

A

Phase 2

35
Q

Which phase of liver metabolism is catabolic

A

Phase 1

36
Q

What happens in hepatic failure (liver failure)

A

Detoxification of ammonia via urea cycle to urea (excreted by kidneys) fails
Blood ammonia levels rise (hyper ammonia) excreting toxic effect on CNS causing incoordination, drowsiness, coma and ultimately death

37
Q

How can you treat hepatic failure

A

Administer Lactuolose

Antibiotics - suppress colonic flora and this inhibit

Y1 GI (41 decks)

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