Lipid Metabolism Flashcards
Types of Lipids
- Triglycerides: used in energy metabolism
- Phospholipid: structural, blood clotting, myelin sheath, and ALL cell membranes
- cholesterol: precursor of steroid hormones and bile salts. synthesized in the liver
What is a chylomicrons function?
-protein molecule synthesized in the wall of the small intestine that is involved in the transport of dietary triglycerides and cholesterol that have been absorbed in the GI tract.
Transports triglycerides to adipose tissue and skeletal muscle tissue for storage.
Cholesterol taken up by the liver and binds to one of the lipoproteins.
What happens to the cholesterol that is taken up by the liver?
what is the rate limiting step in cholesterol synthesis?
- synthesized into VLDL or is excreted in the bile.
- Rate limiting step is the enzyme HMG-CoA in cholesterol synthesis.
Are cholesterol and triglycerides soluble in plasma? How do they get around?
-cholesterol and triglycerides are insoluble in plasma, they are encapsulated by lipoproteins.
WHat are the 5 types of Lipoproteins? What is their make up? WHats their function?
- Chylomicrons
- Very low density lipoprotein(VLDL)
- Intermediate lipoprotein (IDL)
- low density lipoprotein (LDL)
- high density lipoprotein (HDL)
- top=highest triglyceride content and lowest protein content
- bottom=highest protein content and lowest triglycerides.
Made up of phospholipids and apoproteins, cholesterol and triglycerides in the core.
*the triglyceride and cholesterol content vary.
-Function: transport of cholesterol and triglyceride.
Explain Lipid Metabolism
- dietary lipid intake
- becomes chylomicron that enters blood and transfers triglycerides and cholesterol to adipose and skeletal muscle tissues.
- trigylceride is taken up by these cells and the cholesterol remains.
- cholesterol is taken up by the liver, liver synthesizes it to VLDL or excretes it in the bile.
- VLDL brings its newly endogenously synthesized triglyceride and cholesterol to adipose and skeletal muscle tissue.
- After some triglyceride is dropped off it becomes IDL fragment, which has reduced triglyceride and enriched cholesterol content.
- IDL taken up by liver and recycled to form VLDL or converted to LDL.
-HDL is synthesized in the liver and is responsible for reverse transport of cholesterol from plaques back to the liver where it is excreted.
What two lipoproteins does the liver secrete?
VLDL and HDL
What happens to LDL in the blood?
- LDL is taken up by mfs in the arterial wall and can result in the accumulation of:
- insoluble cholesterol esters
- formation of foam cells
- development of atherosclerosis
What are some things to reduce/increase HDL?
- Reduce: smoking and metabolic syndrome
- increase: regular exercise and moderate alcohol consumption
what is Xanthalasma? Arcus Senilis?
- cholesterol deposits throughout the body
- senilis: sign of high cholesterol that manifests as a white ring around the iris.
What are apoproteins?
Where are they synthesized?
Is there a genetic component to apoproteins?
- apoproteins are part of lipoproteins that control the interactions and ultimate metabolic fate of lipoproteins….regulate lipid transport and metabolism
- synthesized in the small intestine and liver
- yes, if you are apoprotein deficient you are more likely to have lipid deposition in arteriole walls. May have HDL deficiency resulting in promotion of atherosclerosis.
Explain how Atherosclerosis develops
- accumulation of LDL (lipoprotein) within the inner layer of arterial wall.
- chemical oxidation of lipoprotein leads to local INFLAMM involving mfs which ingest lipoproteins and form foam cells.
- accumulation of foam calls contribute to fatty lesion formation which, overtime, progress to fibrous plaques.
- fissure may develop in a plaque exposing underlying tissue to plateletes
- platelet adhesion, activation and aggregation lead to thrombus formation which may partially or completely occlude the vessel.
what is the main carrier or triglycerides? cholesterol? protein?
Triglycerides: VLDL
Cholesterol: LDL
Protein: HDL
saturated fatty acids have what kind of bonds?
monosaturated FA?
Polyunsaturated FA?
- Sat’d FA: have single bonds between carbon atoms
- -animal fat, cococnut oil, milk, butter, cheese
- mono: contain only one double bond
- -olive oil
- Poly: contain two or more double bonds
- -vegetable oil, soybean oil, sunflower oil.
Ketosis:
- what is this?
- when does this occur?
- result of liver converting fat into FA and ketone bodies, used in place of glucose.
- occurs when the rate of formation of ketones by the liver is greater than the ability to use them.
