lipoprotein metabolism Flashcards
what is a lipoprotein
lipid transporters in blood and lymph
where are lipids absorbed
jejunum
when happens after FA are absorbed into intestine
FA re-esterified to monoglycerides to produce triglycerides
what are the two circulating forms of lipids
albumin - non esterified fatty acids
lipoproteins - phospholipids, TAG, cholesterol and cholesteryl esters
what are the main functions of lipoproteins
transport water -immiscible lipids within the blood stream
delivery of cholesterol to peripheral tissue
reverse transport of cholesterol
what is the structure of a lipoprotein
hydrophobic lipid core
hydrophilic surface layer - phospholipid heads and apolipoproteins
what is the function of apolipoproteins
help stabilization of the structure
activator/inhibitor of lipoprotien lipases
interactions with specific receptor
what are the three lipases and where are they found
lipoprotein lipase (LPL) - in capillaries of tissues (muscle/adipose) to release TG for storage or oxidation - induced by insulin hepatic lipase (HL)- similar to LPL but in liver cells pancreatic lipase (PL) - is secreted from the pancreas and responsible for hydrolysing TG for intestinal absorption
what is cholesterol used for?
component of membranes
precursor of steroid hormones
precursor of bile salts
describe the formation of early atherosclerosis
lipid accumulates in intimal space
activiated endothelial cells express adhesion molecules and recruit inflammatory cells, predominantly monocytes
monocytes migrate into the lipid accumulation and differentiate into macrophages which ingest lipid to become foam cells
what is postprandial lipemia PPL
an increase in serum lipid concentration after food intake
increased PPL is associated with which diseases
CHD and obesity
increased FFA in plasma? could be due to lower FFA uptake into muscle due to lack of exercise? lack of FFA oxidation
how much exercise if sufficient to reduce PPL
30 min brisk walking
what affect does exercise have on endothelial function
improve endothelial function and improve vascular thickness
what are the sources of FA’s
adipose tissue - broken down by hormone-sensitive lipase HSL
intramuscular triglyceride broken down by HSL
plasma triglyceride from chylomicron
what is a chylomicron and what is its function
small fat globule made from lipid and protein
found in blood and lymph
transports lipids from small intestine to adipose tissue
when is lipid mobilisation at its highest
between 25 and 65% Vo2 max
plasma FFA and intramuscular triglyceride oxidation decreases after 85% VO2 max
what is the main metabolite at 85% VO2 max
muscle glycogen
what changes occur in lipid mobilisation as exercise increased from light to moderate intensity
initial drop in plasma FFA due to uptake in muscles and lag time in release from adipocytes
followed by increased FFA from adipose tissue release and decreasd re-esterification occurs through HSL and decreased insulin
exercise induced decreased in re-esterification rates and increase in lipolysis
what happens to lipid mobilisation when exercise increases from moderate to intense
adipose tissue fails to increase lipolysis rate further
decrease in plasma FFA
increased muscle glycogen utilisation
increased intramuscular triglyceride oxidation
