Lipids Flashcards
Steatorrhea is lipid malabsorption due to defects in
bile secretion
pancreatic function
cell uptake
Cholesterol esters are digested into
cholesterol
free Fatty acids
products of lipid absorption form …………….. with bile salts
mixed micelles
Dietary lipids are INSOLUBLE and are therefore packed into
chylomicrons
for export
Chylomicrons are released by exocytosis into
lymph then into the blood
What happens when blood chylomicrons reach tissue?
TAG in chylomicrons is hydrolysed to FA and glycerol (by lipoprotein lipase)
Chylomicrons depleted of TAG are called
chylomicrons remnants
lipoprotein lipase is found in the
capillaries of skeletal muscle and adipose tissue
resulting FA (from chylomicron breakdown)) is used for
energy
re-esterified to TAG for STORAGE
Omega 3 FA are derived from
linoleic acid
Omega 3 lowers ………….. and prevents …………..
cholesterol
atherosclerosis
Phospholipids consist of
2 FA
phosphate group
TAG is digested in the………. by………….
small intestine
pancreatic ligase
Unsaturated
one or more double bond`
saturated
no double bonds
Good fats
polyunsaturated FA (veg oil)
Bad fats
saturated FA (beef)
essential FA
linoleic and linoleic acid
lipids give us what vitamins?
A D E K
In adipose cells TAG are stored as
droplets
TAG is the most efficient
storage form of fuel
How are FA release from stored TAG in adipose tissue?
by hormone sensitive lipase
High plasma glucose and insulin promote
Dephosphorylation of lipase
HSL activated in response to
epinephrine
Lipoproteins
esterified FA
Free FA transported through the blood in complex with
serum albumin
Chylomicrons are TAG
rich
VLDL are TAG
rich
LDL is cholesterol
rich
BAD Cholesterol
HDL is cholesterol and protein
rich
GOOD cholesterol
free esterified FA leaves the adipocyte and binds to albumin
transported to tissue where it is
activated by CoA derivative then OXIDISED
beta oxidation pathway degrades FAs
two carbons at a time
beta oxidation of FA produces
Acetyl CoA
NADH + FADH2 (sources of energy)
Beta oxidation of FA occurs in the
mitochondrial matrix
3 stages of beta oxidation
activation
transport
degradation
Transport of FA into the
mitochondria
FA is activated to form ……… in the ………….
fatty acyl CoA
cytoplasm
CAT-1 (carnitine fatty acyl-transferase) is inhibited by
malonyl CoA
Carnitine from our
diet
lysine + methionine (liver/kidney)
Carnitine shuttle transports …….. from outside to the inside of the……..
long-chain fatty acyl CoA
mitochondria
CAT-1 deficiency
hypoglycaemia
improves with IV glucose
t
therapy for CAT-1 deficiency is to give
medium chain FA that do not require CAT for mitochondrial transport
Degradation 4 step
dehydrogenation (FADH2)
hydration
dehydrogenation (NADH)
thiolysis (acetyl CoA)
Thiolysis produces Acetyl CoA to feed into the
TCA cycle
7 beta oxidations would produce …….. acetyl CoA
8
1 glucose molecules creates
32 ATP
beta oxidation is less efficient in the
peroxisome
Animal cannot convert FA to
glucose
excess acetyl CoA from fat metabolism can be converted into
ketone bodies
which muscles use ketone bodies as fuel?
cardiac and skeletal
uncontrolled diabetes gives
ketone bodies
Where do we get FA?
Acetyl CoA
diet
Carnitine shuttle only occurs when….
citrate concentration in the mitochondria is too high
FA synthesis requires
Acetyl CoA and NADPH
Acetyl CoA carboxylase (ACC) is needed for formation of
malonyl CoA
ACC is activated by……….. and deactivated by …………
citrate
palmitoyl CoA
How many NADPH needed for plamitate synthesis?
14
Acetyl CoA —> FA —-> TAG —->
VLDL —> adipose tissue
Cholesterol is the starting material for the synthesis of
steroid hormones
Cholesterols
component of the cell membrane
made mainly in the liver
found in animal only
Acetyl CoA –> cholesterol –> vit D/ steroid hormones etc etc
Statins lower…
LDL levels
eicosanoids
signalling molecules
eicosanoids are derived from
omega 3 or 6 FA
eicosanoids regulate
inflammatory response
pain and fever
blood pressure
