Lipids Part 2 Flashcards
_______Lipids
Are bonded to other types of molecules
Complex
• Consist of a core of hydrophobic lipids surrounded by amphipathic proteins, phospholipids, and cholesterol
Lipoproteins
Composed of both lipids and proteins, called
apolipoproteins
T or F
• Larger LPP particles have larger core regions (contain relatively more TAG and cholesteryl ester)
True
T or F
The larger the LPP, the more lipid relative to CHON, therefore, lighter in density
True
Lipoproteins
Cassification
(based on ultracentrifugation)
- Chylomicrons [chylos]
- Very-low-density LPP [VLDL]
- Low-density LPP [LDL}
- High-density LPP [HDL]
80% - 90% triglycerides, 2% protein
Chylomicrons
55% - 65% triglycerides,
10% cholesterol,
5% - 10% protein
VLDL
10% triglycerides,
50% cholesterol,
25% protein
LDL
5% triglycerides,
20% cholesterol,
50% protein
HDL
• Location: surface of LPP particles
• Functions:
– Help maintain the structural integrity of LPP
– Serve as ligands for cell receptors
– Act as activators and inhibitors of the various enzymes that modify LPP particles
• Contain “Amphipathic helix”
Apolipoproteins
– Major protein on HDL
– Measure of anti-atherogenic HDL present in plasma
Apo A-I
– Is a large protein with MW 500 kD
– Principal protein on LDL, VLDL, and Chylomicrons
Apo B
Apo B 100 saaa?
LDL
VLDL
Apo B 48
Chylomicrons
Apo B-100
– Is found on…
– Ligand for the LDL receptor
LDL and VLDL
– Exclusively found in chylomicrons
Apo B-48
Apo E
– Found in (3)
– Serves as a ligand for the LDL receptor and the chylomicron remnant receptor
– Apo E2, Apo E3, Apo E4
LDL, VLDL, and HDL
Major lipoproteins
Chylomicrons
VLDL
LDL
HDL
Minor or abnormal lipoproteins
IDL
Lp (a)
Lp (x)
Beta VLDL
Chylomicrons
Account for the_____ of postprandial plasma
Readily float to the top of stored plasma and form a_____ layer – chylous, turbid, milky, cloudy, lipemic plasma/serum
Produced by the____
Deliver dietary (exogenous) lipids to…
turbidity
creamy
intestine
hepatic and peripheral cells
VERY LOW DENSITY LIPOPROTEIN
Contain
apo B-100, apo E, and apo C
VLDL
Produced by the____
Rich in___ like chylomicrons
Account for most of the____ observed in fasting hyperlipidemic plasma specimens but do not form a top, creamy layer
Major carriers of endogenous (hepatic derived) triglycerides
Transfer TAG from the liver to___
liver
TAG
turbidity
peripheral tissue
LOW DENSITY LIPOPROTEIN
• Contains apo
B-100 and apo E
• Primarily formed as a consequence of the lipolysis of VLDL
• Readily taken up by cells via the LDL receptor
– Accounts for the reason that elevated LDL levels promote atherosclerosis
• Significantly smaller than VLDL and chylomicrons
LDL
Smallest and the most dense
Synthesized by both the _____
Can exist either as disk-shaped or as spherical-shaped particles
HIGH DENSITY LIPOPROTEIN
liver and intestine
– Most active form in removing excess cholesterol from peripheral cells
DISCOIDAL HDL
– HDL2
• Larger in size and richer in lipid than HDL3
• May be more efficient in delivering lipids to the liver
– HDL3
SPHERICAL HDL
• Intermediate Density Lipoprotein
• Lipoprotein (a)
• LpX Lipoprotein
• ẞ-VLDL Lipoprotein or Floating ẞ Lipoprotein
Minor:
Abnormal:
• Formed through the metabolism of VLDL in circulation; lipid content, size, and density of IDL is intermediate between VLDL and LDL
Intermediate Density Lipoprotein
• is similar to LDL in terms of density and overall composition, and can be thought of as an LDL particle to which apo(a) has been added, linked to apoB-100 via a disulfide bond
Lipoprotein (a)
• is an abnormal lipoprotein found in patients with biliary cirrhosis or cholestasis, and in patients with familial lecithin/cholesterol acyltransferase (LCAT) deficiency
LpX Lipoprotein
• is an abnormal lipoprotein that accumulates in type 3 hyperlipoproteinemia
ẞ-VLDL Lipoprotein / Floating ẞ Lipoprotein
T or F
Serum lipoprotein concentrations differ between adult men and women
True
T or F
Men and women both show a tendency toward increased total cholesterol, LDL cholesterol, and triglyceride concentrations with age
True
T or F
Circulating levels of total cholesterol, LDL cholesterol, and triglycerides in young children are generally much lower than those seen in adults
True
Diseases associated with abnormal lipid concentrations
DYSLIPIDEMIA
2 CATEGORIES: Dyslipidemia
– Hyperlipoproteinemias
– Hypolipoproteinemias
HYPERLIPOPROTEINEMIA
3 SUBDIVISIONS:
hypercholesterolemia
hypertriglyceridemia
combined hyperlipidemia
• Most closely linked to heart disease
• Increased in LDL cholesterol
• Genetic abnormalities
Hypercholesterolemia
Individuals synthesize intracellular cholesterol normally, but lack, or are deficient in, active LDL receptors
FAMILIAL HYPERCHOLESTEROLEMIA
• Result of an imbalance between synthesis and clearance of VLDL in the circulation
• Life-threatening abnormality because it can cause acute and recurrent pancreatitis
Hypertriglyceridemia
• Presence of elevated levels of serum total cholesterol and triglycerides
• Considered at increased risk of CHD
Combined Hyperlipoproteinemia
– TYPE III HYPERLIPOPROTEINEMIA (Fredrickson Classification
FAMILIAL DYSBETALIPOPROTEINEMIA
– Currently thought to confer increased risk of CHD and CVD
– Can block plasminogen, forming clots along the arterial wall that will not be dissolved
Lp(a) Elevation
• Are abnormalities marked by decreased lipoprotein concentrations
HYPOLIPOPROTEINEMIA
Hypolipoproteinemia (2)
– Hypoalphalipoproteinemia
– Hypobetalipoproteinemia
– Indicates an isolated decrease in circulating HDL
–______ Disease
Hypoalphalipoproteinemia
Tangier
Hpoalphaproteinemia
• HDL concentrations as low as
• Total chole as low as
1-2 mg/dL (0.03 – 0.05 mmol/L)
50 – 80 mg/dL (1.3 – 2.1 mmol/L)
mutations in the ABCA1 gene or the ABCA1 transporter, which mediates the first step of the reverse choesterol transport pathway
Hypoalphalipoproteinemia
• is a disorder consisting of low levels of LDL cholesterol or apolipoprotein B
Hypobetalipoproteinemia
LCAT deficiency (2)
Complete (homozygous
Mild (heterozygous)
• Corneal clouding
• Nephropathy
• Hemolytic anemia
• HDL deficiency
• Fish-eye
– Complete (homozygous)
– Mild (heterozygous)
