GUT- The liver

Question 1

how is the liver involved in the metabolism of carbohydrates

Answer 1

maintain glucose level in the blood
if sugar levels increase- liver removes sugar from the blood and stores it in glycogen
if sugar levels decrease the liver - breakdown glycogen and release sugar into the blood

also stores vitamins and mineral and releases them into the blood when they are needed

Question 2

how is the liver involved in the metabolism of fats

Answer 2

triglycerides are oxidised in hepatocytes to produce energy

lipoproteins are synthesised in the liver

excess carbohydrates and proteins are converted into FA/ TG - stored in adipose
synthesis of large quantities of cholesterol and phospholipids - some are packaged as lipoproteins

Question 3

how is the liver involved in the metabolism of protein

Answer 3

deamination and trans-amination of amino acids - conversion of non-nitrogenous part to glucose and lipids
synthesis of non-essential amino acids
synthesis of nearly all plasma proteins
synthesis of urea which removes ammonia

Question 4

how are Kupfer cells involved in the protective functions of the liver

Answer 4

function as a mononuclear phagocyte system
exposure to blood from the gut contains pathogenic substances
they clear gut-derived endotoxin from portal blood 
important in liver regeneration - release of IL-6 / TNFa - stimulates hepatocytes in G0 to enter G1/S so they can divide

Question 5

what are the functions of bile acids / salts

Answer 5

bile salts - secreted into canaliculi
remove glycine and taurine

bile acids- bacterial metabolism in intestines, digestion of fatty food in intestine, resorption into blood and recirculated into liver

bile pigment - bilirubin

Question 6

scribe the formation of gallstones

Answer 6

caused by an imbalance in the chemical makeup of bile inside the gallbladder

cholesterol gallstone - formed due to a consequence of altered hepatocellular and gallbladder function - overproduction of cholesterol by the liver is a major metabolic precedent of cholesterol gallstones - could be due to obesity / drugs

pigment gallstones - brown / black - formed of calcium bilirubinate and are usually associated with biliary infection

Question 7

what is jaundice

Answer 7

excessive quantities if either free / conjugated bilirubin accumulate in ECF - causes yellow discolouration of the skin, sclera and mucous membrane

Question 8

what are the types of jaundice

Answer 8

pre-hepatic (haemolytic) - excessive breakdown of RBC
excessive unconjugated bilirubin

hepatic - hepatocyte damage (cirrhosis, drugs, hepatitis)
excess conjugated / unconjugated bilirubin

post hepatic - obstructive,
excess conjugated bilirubin, obstruction of passage into into duodenum
enters circulation and into urine (very dark) - due to gallstones, carcinoma,

Question 9

what coagulation factors are synthesised in the liver

Answer 9

fibrinogen
prothrombin
factor (V, VI, IX, X, XII)
vitamin K is essential for the formation of prothrombin and factors II, VII, IX, X

coagulation factors are needed for the clotting process - defect could lead to uncontrolled bleeding

Question 10

what substances can be toxic to the body

Answer 10

bilirubin
ammonia
hormones (steroid hormones)
drugs and exogenous toxins (paracetamol, aspirin, ethanol)

Question 11

what is the process of eliminating toxins from the body by the liver

Answer 11

phase 1- oxidation and reduction in smooth ER - catalysed by CYP450
mainly to make substrates into polar compounds

phase 2- conjugation to make them water soluble

not all drugs use both phases
elimination via ATPase pumps