physiology and pharmacology of the liver Flashcards
what are the metabolic functions of the liver
carbohydrate metabolism
fat metabolism
protein metabolism
what comprises of carbohydrate metabolism
*is hormonally regulated
>gluconeogenesis - to produce glucose from amino acids
>glycolysis - to form pyruvate thence lactate or ACh
>glycogenesis - to store polymerised glucose as glycogen
>glycogenolysis - to release glucose
what does fat metabolism consist of
processing of chylomicron remnants
synthesis of lipoproteins and cholesterol
ketogenesis (in starvation)
what does protein metabolism consist of
synthesis of plasma proteins
transamination and deamination of amino acids
conversion of ammonia to urea
what hormones are deactivated by the liver
insulin
glucagon
anti-diuretic hormone (vasopressin)
steroid hormone
what hormones are activated by the liver
conversion of thyroid hormone
conversion of vitamin D to 25-hydroxyvitamin D2
what are the major functions of the liver
storage
synthesis of proteins
protection
detoxification
what does the liver store
- fat soluble vitamins A D E K in hepatocytes
- water soluble vitamin B12
- iron, copper
- glycogen
what proteins does the liver synthesise for export
- coagulation factors II VII IX and X
- proteins C and S
- albumin
- complement proteins
- apolipoproteins
- carrier proteins
what is the role of Kupffer cells
> they are liver phagocytes that digest particulate matter and old erythrocytes
other than Kupffer cells what the protective function does the liver confer
the production of immune factors
-host defence proteins
how is the liver involved in detoxification
> it has many endogenous substances ie bilirubin as a metabolite of haemoglobin breakdown
and has many exogenous substances ie xenobiotics (drugs and alcohol)
what is bile
it participates in the digestion and absorption of fats and the excretion of products of metabolism
>produced continuously by hepatocytes and bile duct cells
secretion of bile with regards to food intake
> between meals bile is stored and concentrated in the gall bladder as the sphincter of Oddi is closed
during a meal chyme in the duodenum stimulates gall bladder smooth muscle to contract (via CCK and vagal impulses)
-the sphincter of Oddi opens via CCK
-bile spurts into the duodenum via cystic and common bile ducts
what does neutral / slightly alkaline bile assist with
micelle formation
neutralisation of chyme
pH adjustment for digestive enzyme action
protection of the mucosa