16. Lipids
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- Where does fat digestion occur?
- In the small intestine
- What enzyme in the small intestine allows for fat digestion?
- Pancreatic lipase
- What allows H2O-soluble pancreatic lipase to act on lipids?
- Emulsification with bile acids
- What particular bile salt is important in emulsification?
- Lecithin
- What does pancreatic lipase do to lipids?
- Breaks into monoglyceride and 2 free fatty acids.
- What are micelles?
- Aggregates of FFA's, monoglycerides, and bile acids -> allows solubility of the fat digestion products.
- What is the purpose of micelles?
- Uptake of fat digestion products from the small intestine into the enterocytes
- What is the result of poor fat digestion in the intestine?
- Steatorrhea
- What is fat when it is eaten?
- Triglyceride
- What happens after enterocytes uptake micelles? (2 possibilities)
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1. Re-esterification of mono-glyceride+FFA to Triglyceride
2. Formation of chylomicrons - What are chylomicrons made of?
- Triglyceride, Cholesterol, Cholesterol esters, surrounded by Protein and phospholipids.
- What are chylomicrons a specific class of?
- Lipoproteins
- Where do chylomicrons go after formation in enterocytes?
- To the lymphatic sytem, to the thoracic duct, into circulation.
- What are the target tissues of chylomicrons?
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-Liver
-Muscle
-Adipose tissue - What are the normal body functions of lipids?
-
-Hormones
-Energy
-Digestion
-Membrane components
-Insulate nerves - What happens to chylomicrons in circulation when they reach the tissue?
- They get broken down to energy and chylomicron remnants for storage or energy use.
- What enzyme is responsible for chylomicron breakdown in circulation?
- Lipoprotein lipase
- What is Cholesterol made from?
- Acetyl Co-A
- Where is cholesterol made?
- In the liver and gut
- What are 4 sterol derivatives?
-
-Hormones (steroids)
-Bile salts (by the liver)
-Vitamin D
-Cholesterol - What are the 5 classes of lipids?
-
1. Sterol derivatives
2. Fatty acids
3. Glycerol esters
4. Sphingosine derivatives
5. Terpenes - What are the terpenes?
- Vitamins A, K, and E
- Where is esterification of chylomicrons done? (going back)
- In the vascular component
- What 2 enzymes catalyze esterification?
-
-LCAT (lecithin)
-ACAT (acyl) - Which apolipoprotein may be associated with increased risk of Coronary artery disease (CAD)?
- Apolipoprotein B
- What methods are useful in measuring lipoproteins? (2)
-
-Ultracentrifugation
-Electrophoresis - What apolipoprotein is the major one in HDL?
- Apo A
- What is the more protective lipoprotein?
- HDL
- What apolipoprotein is the major on ein LDL?
- Apo B
- Which lipoprotein is associated with high risk of CHD?
- LDL
- List the lipoproteins:
-
-Chylomicron
-VLDL
-IDL
-LDL
-HDL - What is the source of chylomicron?
- the intestine
- What is the source of VLDL?
- the liver
- What is the source of IDL and LDL?
- VLDL
- What is the source of HDL?
- VLDL and Chylomicrons
- Where is HDL synthesized?
- In the liver and intestines
- Which lipoprotein has the highest percent of tryglyceride?
- VLDL
- Which lipoprotein has the highest percent of cholesterol?
- LDL! not hdl
- What makes HDL so heavy?
- It has the highest percent of protein
- what lipid is important in fetal development?
- DHA - from omega-3 fatty acids
- How does DHA aid fetal develpment?
- It provides structural fatty acid in brain gray matter and retinal tissue - important for brain and eye maturation.
- What are the 4 general types of methods for lipid analysis?
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1. Plasma appearance
2. Cholesterol measurement
3. HDL measurement
4. LDL measurement - What are specifications for evaluating plasma appearance?
- Store at 4'C overnight; can use EDTA plasma
- What are the 2 types of methods for total cholesterol measurement?
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1. Enzymatic
2. Chemical - What is the principle of the enzymatic cholesterol method?
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1. Cholesterol is broken down to produce peroxide;
2. Peroxide is broken down by 2a) Peroxidase -> color
2b) Catalase -> NADPH - What are 2 chemical methods for cholesterol measurement?
-
1. Liebermann-Burchard
2. Abell - which chemical method has higher sensitivity?
- Abell
- What is a drawback to the Liebermann-Burchard method?
- It uses caustic reagents - H2SO4 and acetic anhydride.
- What are 2 types of methods for HDL measurement?
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1. Ultracentrifugation
2. Precipitation - List 4 reagents that will precipitate HDL:
-
1. Heparin-Manganese Chloride
2. Dextran Sulfate
3. Phosphotungstate
4. Polyethylene glycol - What is the preferred amt of HDL in the body, high or low?
- HIGH - it helps prevent CHD
- What are 2 options for measuring LDL?
-
1. Direct assay
2. Calculation - What is the calculation for LDL?
- Friedwald calculation
- What are limitations for doing the Friedwald calculation?
- Can only be done on fasting specimens, with Triglyceride levels above (?) 400
- What is the Friedwald calculation?
- LDL = Total Chol - (Try/5)+HDL
- How is LDL directly measured?
- Enzymatically
- What is the WHO classification of hyperlipidemias based on?
- Plasma appearance, Cholesterol levels, Triglyceride levels, and electrophoretic patterns.
- How many WHO classes are there?
- 5
- What pattern follows the WHO classes?
-
1 = Reference, Clear plasma
Type 1 = Milky
Type 2a = Clear
Type 2b = Clear-Turbid
Type 3 = Turbid
Type 4 = Turbid-Opaque
Type 5 = Super milky - What is Niemann-Pick disease?
- Deficiency of enzyme Sphingomyelinase
- What results from Niemann -Pick disease?
- Excess sphingomyelin in the liver, spleen, brain, and bone marrow
- Who is primarily affected by Niemann-Pick?
- Children; usually die within several years.