Introduction to Lipids

Question 1

Energy Storage

Answer 1

cellular energy is stored short term (labile)
there is a limit of how much ATP can be stored
energy is stored long term as large, stable efficient energy precursors - carbs and fats

Question 2

Fatty Acids

Answer 2

single straight carbon chains + COOH

some have double bonds - unsaturated

Question 3

Cholesterol

Answer 3

essential components of cell membranes
precursors of bile acids, steroid hormone and vitamin D
made in liver or from diet
major emphasis on recycling - endogenous pathway

Question 4

Cholesterol Esters

Answer 4

a large portion of plasma cholesterol is esterified (75%)
broken down by lipases to free cholesterol and fatty acids
cholesterol is amphipathic, but hydrophobic when esterified

Question 5

Ketone bodies

Answer 5

made from acetyl CoA during fasting by liver
lasts for 5 hours
acetoacetic acid and beta-hydroxybutyric acid
Acetone is a waste product, made by decarboxylation

Question 6

Double Bonds

Answer 6

unsaturated chains have a lower melting point so are more liquid at body temp - increase in fluidity
most natural fatty acids cis - create a kink which interferes with stacking and solidification
fatty acids in diet affect plasma cholesterol and triglyceride levels - saturated fats are bad (more LDL)

Question 7

Exogenous Pathway

Answer 7

gut to liver and periphery
lipids from diet packaged by s intestine into chylomicrons
chylomicrons taken up by liver

Question 8

Endogenous Pathway

Answer 8

liver to periphery

lipid from liver packaged into VLDL

Question 9

Reverse Cholesterol Transport

Answer 9

Periphery to liver
occurs when lipid supplies in liver are being exhausted
a sign of reduced body lipid
HDL in blood indicates reverse path activity

Question 10

Bile Production

Answer 10

Liver to gut
Bile released into cystic duct
Cholesterol converted into bile acids
Most bile acids are reabsorbed by gut and returned to the liver

Question 11

Enzymes and Receptors

Answer 11

needed to mover fats in and out of blood vessels
e.g. lipoprotein lipase - metabolises TG to fatty acids and glycerol (TG needs to be metabolised to remove triglycerides from VLDL and move TG across capillary membrane)

Question 12

LDL
HDL
VLDL
IDL

Answer 12

can get incorporated in atheromas, storage for excess cholesterol, dangerous.
lower cv risk, lipid transport from fat to liver, appears when cholesterol is being used up.
signifies risk of atheromas, used in exogenous and endogenous pathway, removes TG from periphery.
results from VLDL losing TG to periphery, IDL will become LDL, sign of CV risk

Question 13

Hypercholesterolaemia

Answer 13

High fasting levels of plasma cholesterol, increased risk of arteriosclerosis, due to a combination of environmental and genetic factors
treated with statins

Question 14

metabolic syndrome

Answer 14

group of risk factors leading to increased risk for CAD, stroke, T2 diabetes. Main causes - insulin resistance and central obesity.
includes increased BP