Dyslipidaemias: diagnosis, pharmacotherapy and prevention Flashcards
What does cholesterol mean?
- cholos = bile - steros = solid - ol = alcohol
What does atherosclerosis mean?
- atheros = greek work for glue - sclerosis = german for hardening
What is the basic structure of a triglyceride?
- glycerol backbone - three fatty acids
What is a lipoprotein?
- proteins that are soluble in water - able to carry lipids around the body
What are the 3 main components of lipproteins?
1 - cholesterol 2 - triglycerides 3 - apoproteins
What is the primary aspect of lipoproteins that determines the structure and function?
- apoproteins
What is the main element of the core of lipoproteins?
- cholesterol esters - triglycerides
What is the main element of the outer surface of lipoproteins?
- apoproteins - phospholipids - cholesterol free
What is the major difference between free and esterified cholesterol?
- free = biologically active but cytotoxic - ester = safe/protected form for storage
What are the 2 different lipoproteins that we need to be aware of that are commonly measured in the blood?
- low density lipoproteins (LDL) - high density lipoproteins (HDL)
Why are low density lipoproteins (LDL) classed as the bad lipoproteins?
- they contain the majority of the bodies cholesterol - stored in body as fat
Where is the majority of the cholesterol in the body prodcued?
- liver
What is 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA)?
- intermediate precursor of cholesterol
What is the rate limiting step and the target of statins in an attempt to reduce cholesterol synthesis?
- 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase - HMG-CoA converted to Mevalonate
How are bile acids formed?
- synthesised in liver from cholesterol
What is the function of bile acids?
- secreted into GIT by gall-bladder - act as emulsifiers for fat digestion
What is the basic principle of exogenous lipid transport?
- lipids digested in GIT - processed into chylomicrons - absorbed into lymphatic system
Once chylomicrons have been absorbed during exogenous lipid transport, how are triglycerides and fatty acids absorbed by capillaries?
- lipoprotein lipase released from capillaries - triglycerides released from chylomicrons
Once chylomicrons have moved throughout the body, what happens to the remnants of them during exogenous lipid transport?
- remnants rich in cholesterol return to liver - cholesterol and bile are secreted into GIT
What is the basic principle of endogenous lipid transport?
- liver processing of lipoproteins - lipoproteins delivered around the body
In endogenous lipid transport what are the 2 main lipoproteins released from the liver?
- very low density lipoproteins (VLDL) - low density lipoproteins (LDL)
In endogenous lipid transport very low density lipoproteins (VLDL) are created and released from the liver into the circulation. What is the first thing that happens to them in the capillaries?
- lipoprotein lipase is released from capillaries - TAG and fatty acids are released from VLDL and absorbed by capillaries
In endogenous lipid transport once very low density lipoproteins (VLDL) have had most of their TAGs absorbed by capillaries, what do VLDL become?
- intermediate lipoproteins
In endogenous lipid transport what happens to the intermediate lipoproteins that are formed from VLDL?
- enter the liver - processed into low density lipoproteins
In endogenous lipid transport what happens to low density lipoproteins (LDL)?
- LDLs are transported to peripheries - LDL receptors bind to LDL - cholesterol is stored in tissues
What is the reverse pathway involved in lipid transport?
- free cholesterol in tissues is absorbed by high density lipoproteins (HDL) - HDL transport cholesterol to liver for processing
What are the 3 pathways for lipid transport in the body?
1 - exogenous 2 - endogenous 3 - reverse
What is included in total cholesterol, and what is the healthy target?
- LDL and HDL - <5mmol/L - LDL/HDL ratio >3.5
What is the healthy target for LDL?
- <3mmol/L
What is the healthy target for HDL?
- >1.5mmol/L
What is the healthy target for triglycerides?
- 0.5 - 2mmol/L
What is primary dyslipidaemia?
- error in metabolism - generally caused by genetics
What are the 2 most common things affected by primary dyslipidaemia?
- abnormal lipoprotein structure - abnormal lipoprotein receptors