Lipids Cholesterol
• Unsaturated steroid alcohol
Fats
• Most complex
• Biochemical compounds medically referred to as lipids
• Contain 4 rings: A, B, C, D
• Mostly C-H bonds
• Amphipathic
• Calorie - unit of energy
o Only hydroxyl group in A ring is hydrophilic
o Present: Joles
• Found in surface of lipid layers
• Functions:
• Synthesized in liver
o Rich source of energy/storage of excess
• Precursor of 5 major classes of steroids
calories
Progestin
o Hormone or hormone precursor
Glucocorticoids
▪ Adrenal steroids are from cholesterol Mineralocorticoids
o Structural cell component Androgen
o Insulation • Can exist in an esterified form (cholesterol ester)
• Dyslipidemia = abnormal lipoprotein concentration • Not readily catabolized by the cell
• Plasma lipids = lipoproteins = atherosclerosis • Converted in the bile → bile acids → cholesterol,
o LDL = lechon de leche cholic acid
o Leading cause of death • Can be converted to Vitamin D3 (active form)
o From 7-dehydrocholesterol
Major Lipids
• Fatty Acid Lipoproteins
• TAG • Composed of lipids and proteins (apolipoproteins)
• Phospholipids • Class of proteins synthesized by the liver or intestines
• Cholesterol • There proteins form a "transport vesicle" with the
lipids to facilitate lipid circulation
Fatty Acid • 10-1200 nm
• Short-chained, 4-6 carbon chain • Size variation is attributed to TAG and cholesterol
• Medium chain 6-12 content
• Long chain 12-26 • The bigger the LP, the higher the lipid content
• Small amount is present in plasma in un-esterified o ↑ density = ↑ protein = ↑ lipid o ↑ lipid = ↑ size
form o ↑density = ↑ size
• Derived from the hydrolysis of TAG • Core
• Reference Value 9-15 mg/dL o Triglyceride
o Cholesteryl ester (esterified form)
Triglycerides • Surface
• 3 molecules of fatty acids, 1 molecule of glycerol o Free cholesterol
• Hydrophobic o Phospholipid
• Do not contain charges
o Apolipoproteins
• Main storage lipid of man (95%)
▪ Responsible for synthesis and
• Predominant form: glyceryl ester
breakdown of lipoproteins
• Allows the body to store long-carbon chain
▪ Activator and inhibitors of enzyme
• Used in fasting state
▪ Also called, Lipid exchange mediator
• Synthesize 60-130 g daily
• Fractions
• Resynthesized in intestine and combine with
o Chylomicrons
cholesterol and Apolipo-b-protein
• Fat found in food is is 1-2% o VLDL
• 2 kinds: o LDL
o HDL
Saturated Solid at RT
Unsaturated w/ bends and kinks Oil at RT Lipid Metabolism
1. Emulsification of fats
Phospholipid a. Food is ingested
• Contain 2 fatty acids b. Proteins and sugars are degraded by salivary
• Most abundant lipids derived from phosphatidic acid enzymes
• Originated in liver and intestines c. Fat cannot be digested in the mouth. Initial
• Formed by 2 conjugations digestion occurs in the stomach. Most digestion
o Fatty acid occurs in intestines.
o Phosphorylated glycerol d. Gallbladder contracts releasing bile acids.
• Amphoteric ▪ Large fat globule (bile acids) → micelles
, • Short →
• Lipid carrier protein →
• Liver
• Long →
• TAG →
• Chylomicrons →
• Lymph
▪ Monoglycerol
•TAG →
•Chylomicrons →
•Lymph
2. Exogenous Pathway
o Use of chylomicrons
Chylomicron
• Density: <0.93 g/mL
• High lipid content; larger
• Cholesterol poor
• Contains apo B-48
• Largest LP and least dense
• Presence of chyle (chylous sample)
• Rich in exogenous TAG (85-95%)
• Poor in cholesterol
• Packed with dietary lipids in the intestines VLDL / pre-beta lipoprotein
• Of dietary origin • Density: 0.93-1.006 g/mL
• Contribute to turbidity of specimen • Smaller than chylo
• Seen in postprandial plasma • Rich in endogenous TAG
• Fasting samples should not be chylous, but may be • Produced in the liver and has apo B-100, apo E, and
lipemic apo Cs
• Principal role: • Cause turbidity in fasting hyperlipidemic plasma
o Delivery of dietary lipids to the liver and • Not of dietary origin
peripheral cells • Lower L:P ratio compared to chylo
▪ Nascent chylomicrons - newly • Pathway
synthesized chylos o VLDL to IDL to LDL
▪ Apo E allows chylos to enter liver o LDL is one of the major cholesterol transporter
▪ Apo CII activates LPL
▪ Hydrolysed by lipoprotein lipase to form
chylomicron remnants
LDL / beta lipoprotein
• Density: 1.019-1.063 g/mL
• 50% of total LP's in plasma
• Contains apo B-100
• Unsaturated steroid alcohol
Fats
• Most complex
• Biochemical compounds medically referred to as lipids
• Contain 4 rings: A, B, C, D
• Mostly C-H bonds
• Amphipathic
• Calorie - unit of energy
o Only hydroxyl group in A ring is hydrophilic
o Present: Joles
• Found in surface of lipid layers
• Functions:
• Synthesized in liver
o Rich source of energy/storage of excess
• Precursor of 5 major classes of steroids
calories
Progestin
o Hormone or hormone precursor
Glucocorticoids
▪ Adrenal steroids are from cholesterol Mineralocorticoids
o Structural cell component Androgen
o Insulation • Can exist in an esterified form (cholesterol ester)
• Dyslipidemia = abnormal lipoprotein concentration • Not readily catabolized by the cell
• Plasma lipids = lipoproteins = atherosclerosis • Converted in the bile → bile acids → cholesterol,
o LDL = lechon de leche cholic acid
o Leading cause of death • Can be converted to Vitamin D3 (active form)
o From 7-dehydrocholesterol
Major Lipids
• Fatty Acid Lipoproteins
• TAG • Composed of lipids and proteins (apolipoproteins)
• Phospholipids • Class of proteins synthesized by the liver or intestines
• Cholesterol • There proteins form a "transport vesicle" with the
lipids to facilitate lipid circulation
Fatty Acid • 10-1200 nm
• Short-chained, 4-6 carbon chain • Size variation is attributed to TAG and cholesterol
• Medium chain 6-12 content
• Long chain 12-26 • The bigger the LP, the higher the lipid content
• Small amount is present in plasma in un-esterified o ↑ density = ↑ protein = ↑ lipid o ↑ lipid = ↑ size
form o ↑density = ↑ size
• Derived from the hydrolysis of TAG • Core
• Reference Value 9-15 mg/dL o Triglyceride
o Cholesteryl ester (esterified form)
Triglycerides • Surface
• 3 molecules of fatty acids, 1 molecule of glycerol o Free cholesterol
• Hydrophobic o Phospholipid
• Do not contain charges
o Apolipoproteins
• Main storage lipid of man (95%)
▪ Responsible for synthesis and
• Predominant form: glyceryl ester
breakdown of lipoproteins
• Allows the body to store long-carbon chain
▪ Activator and inhibitors of enzyme
• Used in fasting state
▪ Also called, Lipid exchange mediator
• Synthesize 60-130 g daily
• Fractions
• Resynthesized in intestine and combine with
o Chylomicrons
cholesterol and Apolipo-b-protein
• Fat found in food is is 1-2% o VLDL
• 2 kinds: o LDL
o HDL
Saturated Solid at RT
Unsaturated w/ bends and kinks Oil at RT Lipid Metabolism
1. Emulsification of fats
Phospholipid a. Food is ingested
• Contain 2 fatty acids b. Proteins and sugars are degraded by salivary
• Most abundant lipids derived from phosphatidic acid enzymes
• Originated in liver and intestines c. Fat cannot be digested in the mouth. Initial
• Formed by 2 conjugations digestion occurs in the stomach. Most digestion
o Fatty acid occurs in intestines.
o Phosphorylated glycerol d. Gallbladder contracts releasing bile acids.
• Amphoteric ▪ Large fat globule (bile acids) → micelles
, • Short →
• Lipid carrier protein →
• Liver
• Long →
• TAG →
• Chylomicrons →
• Lymph
▪ Monoglycerol
•TAG →
•Chylomicrons →
•Lymph
2. Exogenous Pathway
o Use of chylomicrons
Chylomicron
• Density: <0.93 g/mL
• High lipid content; larger
• Cholesterol poor
• Contains apo B-48
• Largest LP and least dense
• Presence of chyle (chylous sample)
• Rich in exogenous TAG (85-95%)
• Poor in cholesterol
• Packed with dietary lipids in the intestines VLDL / pre-beta lipoprotein
• Of dietary origin • Density: 0.93-1.006 g/mL
• Contribute to turbidity of specimen • Smaller than chylo
• Seen in postprandial plasma • Rich in endogenous TAG
• Fasting samples should not be chylous, but may be • Produced in the liver and has apo B-100, apo E, and
lipemic apo Cs
• Principal role: • Cause turbidity in fasting hyperlipidemic plasma
o Delivery of dietary lipids to the liver and • Not of dietary origin
peripheral cells • Lower L:P ratio compared to chylo
▪ Nascent chylomicrons - newly • Pathway
synthesized chylos o VLDL to IDL to LDL
▪ Apo E allows chylos to enter liver o LDL is one of the major cholesterol transporter
▪ Apo CII activates LPL
▪ Hydrolysed by lipoprotein lipase to form
chylomicron remnants
LDL / beta lipoprotein
• Density: 1.019-1.063 g/mL
• 50% of total LP's in plasma
• Contains apo B-100
