lipoprotein metabolism

Question 1

what is a lipoprotein

Answer 1

lipid transporters in blood and lymph

Question 2

where are lipids absorbed

Answer 2

jejunum

Question 3

when happens after FA are absorbed into intestine

Answer 3

FA re-esterified to monoglycerides to produce triglycerides

Question 4

what are the two circulating forms of lipids

Answer 4

albumin - non esterified fatty acids

lipoproteins - phospholipids, TAG, cholesterol and cholesteryl esters

Question 5

what are the main functions of lipoproteins

Answer 5

transport water -immiscible lipids within the blood stream
delivery of cholesterol to peripheral tissue
reverse transport of cholesterol

Question 6

what is the structure of a lipoprotein

Answer 6

hydrophobic lipid core

hydrophilic surface layer - phospholipid heads and apolipoproteins

Question 7

what is the function of apolipoproteins

Answer 7

help stabilization of the structure
activator/inhibitor of lipoprotien lipases
interactions with specific receptor

Question 8

what are the three lipases and where are they found

Answer 8

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

Question 9

what is cholesterol used for?

Answer 9

component of membranes
precursor of steroid hormones
precursor of bile salts

Question 10

describe the formation of early atherosclerosis

Answer 10

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

Question 11

what is postprandial lipemia PPL

Answer 11

an increase in serum lipid concentration after food intake

Question 12

increased PPL is associated with which diseases

Answer 12

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

Question 13

how much exercise if sufficient to reduce PPL

Answer 13

30 min brisk walking

Question 14

what affect does exercise have on endothelial function

Answer 14

improve endothelial function and improve vascular thickness

Question 15

what are the sources of FA’s

Answer 15

adipose tissue - broken down by hormone-sensitive lipase HSL
intramuscular triglyceride broken down by HSL
plasma triglyceride from chylomicron

Question 16

what is a chylomicron and what is its function

Answer 16

small fat globule made from lipid and protein
found in blood and lymph
transports lipids from small intestine to adipose tissue

Question 17

when is lipid mobilisation at its highest

Answer 17

between 25 and 65% Vo2 max

plasma FFA and intramuscular triglyceride oxidation decreases after 85% VO2 max

Question 18

what is the main metabolite at 85% VO2 max

Answer 18

muscle glycogen

Question 19

what changes occur in lipid mobilisation as exercise increased from light to moderate intensity

Answer 19

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

Question 20

what happens to lipid mobilisation when exercise increases from moderate to intense

Answer 20

adipose tissue fails to increase lipolysis rate further
decrease in plasma FFA
increased muscle glycogen utilisation
increased intramuscular triglyceride oxidation