biochem of liver Flashcards
what does retinol binding protein do
transport vitamin A
what are the functions of plasma proteins
maintenance of osmotic pressure transport hydrophobic substances pH buffering enzymatic eg blood clotting immunity
what does vit A deficiency cause
visual impairment
name two alpha globulins
retinol binding protein and ceruloplasmin
name two beta globulins
transferrin and fibrinogen
what does transferrin trnasort
Fe3+
what is transferrin an indicator of
iron deficiency
what is fibrinogen
inactive form of fibrin
involved in blood clotting
what does albumin do
regulate the oncotic pressure of blood
what stimulate the production of albumin
insulin
when are albumin levels low
liver disease
starvation or low protein diet
how does albumin bind molecules
multiple hydrophobic clefts - low affinity but high capacity
what endogenous substances does albumin transport
fatty acids, bilirubin and thyroid hormones
what exogenous substances does albumin transport
drugs eg aspirin
how is iron transported
Fe3+ bound to transferrin
how is iron stored
in cells bound to ferritin
how is copper transported in blood
bound to ceruloplasmin
are steroid and thyroid hormones hydrophobic or philic
hydrophobic
what are lipoproteins core composed of
hydrophobic molecules - cholesterol esters adn triglycerides
what are lipoproteins shell composed of
apoproteins and polar lipids
describe the exogenous pathway of lipid transport
ingested TG and cholesterol are combined with apoproteins to form chylomicrons.
via lymphatic system chylomicrons enter bloodstream and go to muscle and adipose tissue
hydrolysed by LPL yielding fatty acids which enter the tissues
liver takes up residual chylomicron residues and breaks them down to give cholesterol
what is the function of VLDL
Transport of endogenous fat to peripheral cells
describe the endogenous pathway
liver forms VLDL which are hydrolysed by LPL yielding FFA which go to tissues and VLDL becomes IDL and then LDL
LDL only now has apo B100
LDL taken up by liver mainly, the rest distributes cholesterol to the peripheral tissues
HDL role
cholesterol is removed from tissue by HDL which is made from Apo A1 etc
it accumulates cholesterol and transfers it to VLDL, LDL and IDL which return it to the liver
what does the liver store
vitamins A D and B12
iron
where does iron come from
breakdown of Hb
what does cholesterol do to cell membranes
harden them
where is cholesterol stored
lipid droplets - core of the molecule
where is the main site of cholesterol synthesis
liver
where is cholesterol also synthesised
intestine, adrenal cortex and gonads
what does HMG CoA reductase catalyse the formation of
mevalonic acid
what is vitamin D
a product of cholesterol
what does vitamin D do
regulate calcium and phosphorus metabolism
what is the most abundant form of Vitamin D in the body
D3
name 3 steroid hormones
corticosteroids
androgens
esterogens
where are corticosteroids made
adrenal cortex
where are androgens made
testis
where are estrogens made
ovary
what is the main product of cholesterol
bile salts
how are bile salts recycled
enterohepatic circulation
in electrophoresis which globulins separate the slowest
gamma - heaviest
beta
alpha
albumin
how can cells regulate their cholesterol uptake
inc LDL receptors when they need more
