MIDTERM LEC: LIPIDS AND LIPOPROTEINS Flashcards
are basically fats
Lipids
Biological function of lipids:
- Fuel
- Insulation
- Protect or cushion internal organs
- Building blocks of other substances in the body
- Constituent of cell walls
comprises 95% of lipids in food and human body
Triglycerides
major class of dietary lipids
Triglycerides
lipids that are solid at RT
FATS
lipids that are liquid at RT
OILS
Phospholipids FORMS:
- 70% Lecithin/Phosphatidylcholine
- 20% Sphingomyelin
- 10% Cephalin
not used for energy
Cholesterol
- precursor of steroid hormones
Cholesterol
constituent of cell membranes
Phospholipids
building blocks of lipids
Fatty Acids
Lipoproteins
Lipoproteins
5 TYPES Lipoproteins
- Chylomicrons
- Very Low Density Lipoprotein
- Intermediate Density Lipoprotein
- Low Density Lipoprotein
- High Density Lipoprotein
Most dense to the least (based on density):
HDL > LDL > VLDL > Chylomicron
function: transport TAG absorbed from the intestine to adipose, cardiac & skeletal muscle
Chylomicron
Heaviest to lightest (based on Molecular Weight):
Chylomicron > VLDL > LDL > HDL
Chylomicron
- Contains:
85-92% TAG
6-12% phospholipids
1-3% cholesterol
1-2% proteins
Responsible for post-prandial turbidity of sample
Chylomicron
- Lipoprotein made in the liver
Very Low Density Lipoprotein (VLDL)
Second hightest TAG content
Very Low Density Lipoprotein (VLDL)
function: Endogenous transport of TAG; body’s internal transport mechanism for lipids
Very Low Density Lipoprotein (VLDL)
VLDL remnant
Intermediate Density Lipoprotein (IDL)
similar to LDL wherein it transports TAG, fats and cholesterol and can also promote the growth of atheroma
Intermediate Density Lipoprotein (IDL)
Responsible for fasting hyperlipidemic turbidity of
sample
Very Low Density Lipoprotein (VLDL)
function: enables fats and cholesterol to move within water-based solution of the bloodstream
Intermediate Density Lipoprotein (IDL)
products of VLDL and IDL metabolism
Low Density Lipoprotein (LDL)
most cholesterol-rich
Low Density Lipoprotein (LDL)
function: principal cholesterol and fat transport in blood
Low Density Lipoprotein (LDL)
known as the “bad cholesterol” because it is involved in the progression of CVD like atherosclerosis or stroke
Low Density Lipoprotein (LDL)
metabolism: 40-60% cleared by hepatic LDL receptors; the rest are taken up by non-hepatic (scavenger) receptors such as macrophages
Low Density Lipoprotein (LDL)
smallest and densest
High Density Lipoprotein (HDL)
most abundant in apolipoproteins
High Density Lipoprotein (HDL)
phospholipid is the main lipidic content
High Density Lipoprotein (HDL)
function: reverse cholesterol transport; transport of excess cholesterol from tissues and cells back to the liver
High Density Lipoprotein (HDL)
known as the “good cholesterol” because it protects against heart disease
High Density Lipoprotein (HDL)
metabolism: synthesized in the liver and intestine
High Density Lipoprotein (HDL)
are proteins that bind lipids to form lipoprotein
Apolipoproteins
They serve as enzyme cofactors and receptor ligands and they also regulate the metabolism of LP and their uptake in tissues
Apolipoproteins
Main protein in HDL; Activator of LCAT for esterification
Apo A-1
VLDL, LDL
Apo B-100
Chylomicrons
Apo B-48
- Lipemia clearing factor
- Activates LPL, targets TAG and removes CM
after meal
Apo C-II
- VLDL, LDL, HDL
- Increased in Alzheimer’s Dx
Apo E
Lipid Storage Diseases:
- NIEMANN-PICK DISEASE
- TANGIER’S DISEASE
- TAY-SACH’S DISEASE
- ANDERSON’S DISEASE
- SITOSTEROLEMIA
Accumulation of sphingomyelin in the bone marrow, spleen and lymph nodes
NIEMANN-PICK DISEASE
- Complete absence of HDL (HDL: 1-2
mg/dL) - Clin cx: orange or yellow discoloration
of tonsils and pharynx
TANGIER’S DISEASE
- Deficiency of hexosaminidase A
- Accumulation of sphingolipids in the brain
TAY-SACH’S DISEASE
Chylomicron-retention disease
ANDERSON’S DISEASE
Plant sterols absorbed and accumulated in the blood and tissues
SITOSTEROLEMIA
Lipid Disorders:
- 1: Hyperchylomicronemia
- 2a: Familial hypercholesterolemia
- 2b: Familial combined hyperlipidemia
- 3: Familial dysbetalipoproteinemia
- 4: Familial hypertriglyceridemia
- 5:
- Abetalipoproteinemia/ Bassen-Kornzweig Syndrome
LPL deficiency (Low cardiac risk, eruptive
xanthoma, recurrent pancreatitis)
1: Hyperchylomicronemia
Defective or deficient LDL receptors (High cardiac risk, xanthelasma, tendon xanthoma, corneal arcus, hypothyroidism, nephritic syndrome)
2a: Familial hypercholesterolemia
Most common (High cardiac risk)
2b: Familial combined hyperlipidemia
Low cardiac risk
4: Familial hypertriglyceridemia
Accumulated VLDL (Eruptive and palmar xanthomas)
3: Familial dysbetalipoproteinemia
Low cardiac risk, eruptive xanthoma
5:
Defective apo β synthesis (Cerebral ataxia, acanthocytosis, fat malabsorption)
Abetalipoproteinemia/ Bassen-Kornzweig Syndrome
INCREASE IN 1: Hyperchylomicronemia
- TAG
- CHYLOMICRONS
ONLY NORMAL IN 1: Hyperchylomicronemia
- CHOLESTEROL
- LDL
- VLDL
INCREASE IN 2a: Familial hypercholesterolemia
- CHOLESTEROL
- LDL
INCREASE IN 3: Familial dysbetalipoproteinemia
- TAG
- CHOLE
- VLDL
NORMAL IN 3: Familial dysbetalipoproteinemia
- CM
- LDL
NORMAL IN 2a: Familial hypercholesterolemia
- TAG
- CM
- VLDL
ONLY NORMAL IN 2b: Familial combined hyperlipidemia
- CM
- TAG, CHOLE, LDL, VLDL (INCREASE)
ONLY NONE IN 4: Familial hypertriglyceridemia
CM
INCREASE IN 4: Familial hypertriglyceridemia
- TAG
- VLDL
NORMAL IN 4: Familial hypertriglyceridemia
- CHOLE
- LDL
ONLY NONE IN 5:
CHOLE
INCREASE IN 5:
- TAG
- CM
- VLDL
DECREASE IN Abetalipoproteinemia/ BassenKornzweig Syndrome
- TAG
- CHOLE
ONLY NORMAL IN 5:
LDL
Abetalipoproteinemia/ BassenKornzweig Syndrome NOT FOUN IN PLASMA
- CM
- LDL
- VLDL