L15: Lipids Flashcards
What are lipoproteins
Lipids bound to apoproteins to become transported in the blood
What are the classes of lipoproteins
Chylomicrons
VLDL
HDL
What are the 2 transport pathway of lipids
Exogenous
Endogenous
Describe the process of the exogenous pathway
1) chylomicron goes into the lymph after enterocytes
2) chylomicron enters the blood
3) apoproteins of the chylomicron recognise the epithelial cell of adipose tissue and bind to it
4) lipoprotein lipase breaks down triglycerides in the chylomicron into fatty acids
5) fatty acids are absorbed
6) remainder of chylomicron known as chylomicron remnant goes to the liver to become absorbed
Describe the process of the endogenous pathway of the liver
1) in the liver cholesterol (from exogenous pathway or from synthesis) and triglyceride is stored
2) triglyceride and cholesterol esters are released out of the liver in lipoproteins called VLDLs
3) VLDLs reach muscle and fat tissue
4) triglycerides in the VLSL are hydrolysed by lipoprotein lipase to give LDL
5) LDLs are taken bake into the liver by binding to LDL receptors on hepatocytes
Describe the endogenous pathway process of extra-hepatic sources
1) epithelial cell turnover releases cholesterol
2) cholesterol is absorbed by lipoprotein called HDL
3) cholesterol esters within the HDL are transferred to LDLs
4) LDLs get taken up by hepatocytes by binding to LDL receptors
How are cholesterol synthesised in hepatocytes
Acetly coA is converted to MVA by HMG coA Reductase
MVA is stored as cholesterol
What is the most common lipoprotein that cholesterol is found in
LDL
What is hyperlipidemia
High levels of lipids in the form of lipoproteins
What are the types of hyperlipidemia
Primary
Secondary
What is the cause of primary hyperlipidemia
Genetic
What is the cause of secondary hyperlipidemia
Due to metabolic disorders such as diabetes, hypothyroidism
What is the consequence of hyperlipidemia
Atherosclerosis
What is atherosclerosis
Blood clot that affect the arteries
What are the 7 classes of drugs that can be used to treat hyperlipidemia
HMG coA Reductase inhibitors PSK9 Inhibitors Fibrates Bile-acid binding resins Exetimibe Nicotinic Acid Fish oil
What is the role of HMG coA Reductase
1) Inhibit HMG coA reductase enzyme in the endogenous pathway to reduce cholesterol synthesis in hepatocytes
2) Reduced cholesterol synthesis increases LDL receptor transcription
3) This lowers the cholesterol levels in the blood
What class of drug is a HMG coA Reductase
Statin
Name 2 examples of statins
Atorvastatin
Pravastatin
What is the role of PSK9 inhibitors
1) Bind to LDL receptors
2) increase LDL receptors
3) remove LDLs from the blood
What is the role of fibrates
1) fibrates activate nuclear receptors
2) increase lipoprotein lipase enzyme
3) VLDLs, triglycerides decrease
Name 2 fibrates
Bezafibrate
Gemfibrozil
What is the role of bile acid binding resins
1) bile acid binding resins bind to bile acid
2) bile acid cannot be recycled and absorb cholesterol
3) LDL receptors increase
4) cholesterol and LDL levels decrease
What is the role of ezetimibe
1) Bind to a receptor NCP1L1
2) cholesterol is not absorbed in the intestine
What is the role of nicotinic acid
Reduces the levels of triglyceride in the liver
