9 Questions
What are biomolecules that are soluble in organic solvents like hexane and insoluble in water?
Lipids
Which type of lipids can be broken down into simpler molecules by hydrolysis?
Hydrolysable
Cholesterol is a non-hydrolysable lipid.
True
HDL is also known as ______ cholesterol.
Good
Match the following lipoproteins with their descriptions:
VLDL = Secreted by the liver and export triglycerides to peripheral tissues LDL = Product of intravascular metabolism of triglyceride-rich lipoprotein, VLDL HDL = Protective lipoproteins participating in reverse cholesterol transport
What are the two main types of lipids based on their hydrolysis properties?
Hydrolysable and non-hydrolysable lipids
What are the products obtained upon hydrolysis of triglycerides?
Free fatty acid and glycerol
Chylomicrons are primarily composed of ________.
triglycerides
HDL is often referred to as 'good cholesterol'.
True
Study Notes
Lipid Metabolism
- Lipids are biomolecules that are soluble in organic solvents like hexane and insoluble in water.
- There are two types of lipids:
- Hydrolysable: can be broken down into simpler molecules by hydrolysis through an enzyme (Lipoprotein lipase).
- Examples: triglycerides, free fatty acid (FFA)
- Non-hydrolysable: cannot be broken down into simpler molecules by hydrolysis.
- Example: cholesterol, a steroid used for vitamin D production
- Hydrolysable: can be broken down into simpler molecules by hydrolysis through an enzyme (Lipoprotein lipase).
Lipoproteins
- Lipoproteins are composed of protein and lipids.
- Lipids cannot travel in the bloodstream on their own and need to be bound to proteins.
- Structure of lipoproteins includes:
- Triacylglycerol (another term for triglycerides)
- Cholesteryl esters
- Phospholipids (must be hydrophilic)
- Free cholesterol
- Apoproteins
Types of Lipoproteins
- Chylomicrons:
- Largest lipoproteins
- Primarily composed of triglycerides (80-90%)
- Originate in the small intestine from exogenous dietary fat
- Responsible for the transport of dietary lipids into circulation
- Very Low-Density Lipoproteins (VLDL):
- Secreted by the liver and export triglycerides to peripheral tissues
- Composed primarily of triglycerides (50-70%)
- Derived endogenously from the liver
- Intermediate-Density Lipoproteins (IDL):
- Intermediate in the catabolism of VLDL to LDL
- Remnants of VLDL after depletion of triglycerides
- Average cholesterol content: 30%
- Average triglyceride content: 40%
- Low-Density Lipoproteins (LDL):
- Product of intravascular metabolism of triglyceride-rich lipoprotein, VLDL
- Catabolized chiefly in hepatocytes and other cells by receptor-mediated endocytosis
- Content is primarily cholesterol
- High-Density Lipoproteins (HDL):
- Protective lipoproteins
- Participate in reverse cholesterol transport (tissue -> liver)
Physiological Role of Plasma Lipoproteins
- Transport lipids between tissues
- Events in hemostasis:
- Liberation: complex -> simple
- Absorption: happens in small intestine (surface area increases)
- Distribution: no organ involvement (blood is responsible)
- Metabolism: liver
- Excretion: kidney
- Response: once reabsorb, returns to SC, antagonism; agonism
Physiology of Handling Lipids
- Liver: handles both exogenous and endogenous pathways
- Outside liver: extrahepatic
- Primary site of metabolism: liver
- Primary site of absorption: small intestine
Bile Acid Synthesis
- Sources of cholesterol for bile acid synthesis:
- Primary: De Novo cholesterol biosynthesis
- Alternative: increased HDL, increased hepatic LDL receptors
- Site: Liver (at night)
Dyslipidemia
- Refers to the condition of abnormal lipid levels in the bloodstream
- A major risk factor for coronary heart disease
- Also known as Hyperlipoproteinemia or Hyperlipemia
Atherosclerosis
- The process of forming atheromas, plaques in the inner lining of the arteries
- May lead to coronary artery disease
Coronary Artery Disease
- A condition correlated with high plasma lipid levels of cholesterol and/or triacylglycerol-containing lipoprotein particles
- Primary risk factors:
- Hyperlipidemia
- Hypertension
- Smoking
- Overweight
- Sedentary lifestyle
Lipid Metabolism
- Lipids are biomolecules that are soluble in organic solvents like hexane and insoluble in water.
- There are two types of lipids:
- Hydrolysable: can be broken down into simpler molecules by hydrolysis through an enzyme (Lipoprotein lipase).
- Examples: triglycerides, free fatty acid (FFA)
- Non-hydrolysable: cannot be broken down into simpler molecules by hydrolysis.
- Example: cholesterol, a steroid used for vitamin D production
- Hydrolysable: can be broken down into simpler molecules by hydrolysis through an enzyme (Lipoprotein lipase).
Lipoproteins
- Lipoproteins are composed of protein and lipids.
- Lipids cannot travel in the bloodstream on their own and need to be bound to proteins.
- Structure of lipoproteins includes:
- Triacylglycerol (another term for triglycerides)
- Cholesteryl esters
- Phospholipids (must be hydrophilic)
- Free cholesterol
- Apoproteins
Types of Lipoproteins
- Chylomicrons:
- Largest lipoproteins
- Primarily composed of triglycerides (80-90%)
- Originate in the small intestine from exogenous dietary fat
- Responsible for the transport of dietary lipids into circulation
- Very Low-Density Lipoproteins (VLDL):
- Secreted by the liver and export triglycerides to peripheral tissues
- Composed primarily of triglycerides (50-70%)
- Derived endogenously from the liver
- Intermediate-Density Lipoproteins (IDL):
- Intermediate in the catabolism of VLDL to LDL
- Remnants of VLDL after depletion of triglycerides
- Average cholesterol content: 30%
- Average triglyceride content: 40%
- Low-Density Lipoproteins (LDL):
- Product of intravascular metabolism of triglyceride-rich lipoprotein, VLDL
- Catabolized chiefly in hepatocytes and other cells by receptor-mediated endocytosis
- Content is primarily cholesterol
- High-Density Lipoproteins (HDL):
- Protective lipoproteins
- Participate in reverse cholesterol transport (tissue -> liver)
Physiological Role of Plasma Lipoproteins
- Transport lipids between tissues
- Events in hemostasis:
- Liberation: complex -> simple
- Absorption: happens in small intestine (surface area increases)
- Distribution: no organ involvement (blood is responsible)
- Metabolism: liver
- Excretion: kidney
- Response: once reabsorb, returns to SC, antagonism; agonism
Physiology of Handling Lipids
- Liver: handles both exogenous and endogenous pathways
- Outside liver: extrahepatic
- Primary site of metabolism: liver
- Primary site of absorption: small intestine
Bile Acid Synthesis
- Sources of cholesterol for bile acid synthesis:
- Primary: De Novo cholesterol biosynthesis
- Alternative: increased HDL, increased hepatic LDL receptors
- Site: Liver (at night)
Dyslipidemia
- Refers to the condition of abnormal lipid levels in the bloodstream
- A major risk factor for coronary heart disease
- Also known as Hyperlipoproteinemia or Hyperlipemia
Atherosclerosis
- The process of forming atheromas, plaques in the inner lining of the arteries
- May lead to coronary artery disease
Coronary Artery Disease
- A condition correlated with high plasma lipid levels of cholesterol and/or triacylglycerol-containing lipoprotein particles
- Primary risk factors:
- Hyperlipidemia
- Hypertension
- Smoking
- Overweight
- Sedentary lifestyle
This quiz covers the basics of lipid metabolism, including the characteristics of lipids, types of lipids, and lipoproteins.
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