storage, synthesis and detoxification in the liver

what 3 things does the liver store?

- carbohydrates
- vitamins
- minerals

how does the liver store carbohydrates?

as glycogen

how is glycogen synthesised? (4)

- glucose -> G6P by glucokinase
- G6P -> G1P by phosphoglucomutase
- G1P -> UDP-glucose by UDP-glucose pyrophosphorylase
- UDP-glucose added to glycogen chain by glycogen synthase

which vitamins are stored in the liver?

lipid soluble vitamins:
- A
- D
- E
- K
and vitamin B12

what mineral is stored in the liver?

iron

how is iron stored in the liver?

as ferritin

what substances can the liver synthesise?

- bile salts
- albumin
- clotting factors
- lipoproteins

what does the liver do in terms of detoxification?

- conversion of ammonia to urea
- phagocytosis
- drug metabolism
- alcohol metabolism

what role does the liver play in terms of bilirubin?

excretion of bilirubin

where does bilirubin come from?

product of macrophage destruction of haem molecules

what is the intermediate between haem and bilirubin?

biliverdin

what form is bilirubin initially in?

uncojugated bilirubin

what is the solubility of uncojugated bilirubin?

its lipid-soluble but not water-soluble

how does unconjugated bilirubin travel in the bloodstream?

binds to albumin

where does the unconjugated bilirubin and albumin travel to?

the liver

what does the liver do to unconjugated bilirubin?

hepatocytes conjugate it with glucaronic acid to make it water soluble

where does newly conjugated bilirubin go?

into the biliary system, it is secreted with bile

what happens to conjugated bilirubin in the intestines?

converted to urobilinogen by gut bacteria

what happens to urobilinogen? (2)

either:
90% - converted to stercobilin and excreted as faeces
10% - reabsorbed and excreted via kidneys as urine