Lipids Flashcards
1
Q
Lipids?
A
- biological molecules that are insoluble in aqueous solution and soluble in organic solvents
- fats, essential to the body
2
Q
Major functions of lipids?
A
- serve as structural components of biological membranes
- provide energy reserves, predominantly in the form of triacylglycerols
- both lipids and lipid derivatives serve as vitamins and hormones
- lipophilic bile acids aid in lipid solubilization
- protects nerves and internal organs as thermal covering
- essential for growth
3
Q
Fluid mosaic model of cell membrane? (4)
A
- phospholipid bilayer with many proteins, some integral to the membrane, others attached more loosely
- many other components such as cholesterol and attachment sites for extracellular environment (glycoproteins) and intracellular cytoskeleton
4
Q
What are fatty acids?
A
- long chain hydrocarbons with carboxyl on one end
- carboxyl end is acidic
- the rest is defined by the number of carbons in the hydrocarbon region and the degree of unsaturation
5
Q
Degree of unsaturation?
A
-the presence or absence of C=C double bonds in the hydrocarbon region
6
Q
Unsaturated fatty acid? (5)
A
- has double bonds
- oleic acid
7
Q
Saturated fatty acids? (5)
A
- has only single bonds
- stearic acid
- palmitic acid
- mostly derived from diet
8
Q
Monounsaturated fatty acids? (5)
A
have only one double bond
9
Q
polyunsaturated fatty acids? (5)
A
have more than one double bond
10
Q
Terminology? (6)
A
pic
11
Q
Effects of double bonds? (7)
A
- presence of double bonds gives hydrocarbon region a distinct bend
- saturated are linear
- carbons can be counted from carboxyl end (C2 = alpha, C3= beta)
- can be counted from methyl end (methyl C is omega 1)
12
Q
Where are saturated fatty acids found? (8)
A
- found in dairy and meat and some plant oils (coconut, palm, palm kernel)
- stack together to make solid form at room temp
13
Q
Where are unsaturated fats found? (8)
A
- liquid oils at room temp
- because of bends, they do not stack well and are in liquid form
14
Q
What determines the properties and functions of lipids?
A
- depend on fatty acid chain length (number of carbons) and degree of unsaturation (the more the double bonds the more unsaturated)
- vary among fatty acids
15
Q
What are the most common properties of fatty acids?
A
- an even number of carbons
- between 14-24 carbons
- most common are 16 and 18 carbon fatty acids
16
Q
What conformation do unsaturated fatty acids normally have?
A
- cis
- naturally occurring plants oils remain liquid at ambient temps because of the cis double bonds cause a curved configuration and prevents packing into crystal form
17
Q
What controls membrane fluidity?
A
-controlled by fatty acid composition and cholesterol content
18
Q
What are the classifications of fatty acids? (12)
A
- short chain
- medium chain
- long chain
- very long chain
- because of various lengths, they are digested and metabolized differently
19
Q
Short chain fatty acids sources? properties?
A
- sources: bovine milk, swiss cheese, plants silage
- water soluble nature
- more readily absorbed in the stomach than other fatty acids
- 2 to 3 carbons
20
Q
Medium chain fatty acids sources? properties?
A
- sources: butter fat, coconut and palm kernel oils
- preferentially transported via portal vein to the liver because of their smaller size and greater solubility compared to longer chains
- for entry into mitochondria, medium chains are not carnitine dependent
- 4 to 11 carbons
- fairly soluble in water
21
Q
Long chain fatty acids sources? properties?
A
- sources: animal fats, vegetable and marine oils
- due to size and increased hydrophobic character, long chains are absorbed and metabolized more slowly than short and medium chains
- they need carnitine shuttle for their transport to mitochondrial matrix
- 12 to 20 carbons
- water insoluble
22
Q
Very long fatty acids sources? properties?
A
- sources: plant oil, peanut oil
- exclusively oxidized in peroxisomes
- more than 20 carbons
- water insoluble
23
Q
Why is cows milk not recommended to infants under 12 months old?
A
- because it contains mostly short and medium chains fatty acids and not long chain (palmitic, oleic, linoleic)
- long chain fatty acids play a vital role in brain development in the first year
- long chain polyunsaturated fatty acids play a vital role in overall development of immunity in infants
24
Q
What is the effect of chain length on melting point in saturated fatty acids? (15)
A
- the longer the chain length, the higher the melting point
- fatty acids with melting points above room temp will be solid at room temp (22 degrees C)
25
Q
What is the effect of degree of unsaturation on melting point in unsaturated fatty acids? (17)
A
- the larger the degree of unsaturation (more double bonds) the lower the melting point
- monounsaturated and polyunsaturated fatty acids contribute to membrane fluidity
- most membranes (except brain) adapt to diet induced changes
26
Q
What do diets enriched with monounsaturated fatty acids do for health?
A
- reduce total cholesterol and LDL levels
- LDL is bad cholesterol, HDL is good - cardioprotective effects
- blood pressure lowering effects
- improve insulin sensitivity
- provide anti thrombotic effects
27
Q
What foods are high in monounsaturated fatty acids?
A
- plant oils (canola oil, flaxseed oil, olive oil, peanut oil, pesto sauce, safflower oil, sesame oil, soybean oil, sunflower oil, walnut oil)
- meat fat (pork, beef)
- nuts and seeds (almonds, brazil nuts, natural peanut butter, dry roasted cashews, dry roasted peanuts, dry roasted sunflower seeds, hazelnuts, macadamia nuts, pecans, pine nuts, pistachios, roasted pumpkin seeds, sunflower seeds, walnuts)
- avocado
- olives
- dark chocolate
28
Q
What are DHA and Arachidonic Acid and why are they important?
A
- DHA (docosahexanoic acid synthesized in liver and brain) and Arachidonic Acid
- both are crucial to optimal development of brain and eyes
- important in infant nutrition, routinely added to infant formula
- AA is a major constituent of membrane phospholipids and an important precursor to biological compounds that regulate
29
Q
What are essential fatty acids? (19)
A
- they are polyunsaturated that are essential to humans because the body cannot introduce double bonds past carbon 9 (counting from carboxyl end)
- mammals do not have enzymes (desaturases) that introduce double bonds at C12 and C15, but plants synthesize them both from oleic acid
- Linoleic acid (LA)
- alpha Linolenic acid (ALA)
30
Q
Linoleic acid (LA)? (19)
A
- essential fatty acid
- omega 6, 18:2 (9, 12)
- safflower, soybean, corn, peanut, sunflower oils
- found in egg, meats, grains, nuts, most plant seeds, and some plant oils
- can be desaturated and elongated to arachidonic acid
- LA -> AA, GLA
31
Q
alpha linolenic acid (ALA)? (19)
A
- essential fatty acid
- omega 3, 18:3 (9, 12, 15)
- fish, walnuts, pine nuts, flaxseed, wheat germ, green leafy veggies, soy and canola oil
- found in some plant oils (soybean, linseed, flax)
32
Q
What are two important omega 3 fatty acids? why?
A
- EPA, 20:5 (5, 8, 11, 14, 17)
- DHA, 22:6 (4, 7, 10, 13, 16, 19)
- they are metabolic derivatives of ALA and necessary for synthesis of a number of regulatory compounds in body
- may reduce risk of heart attack
- fish oils contain EPA and DHA
- ALA -> EPA, DHA
33
Q
What do the essential fatty acids (LA, ALA) combine with and form? (22)
A
- combine with cholesterol
- form eicosanoids and steroid hormones
34
Q
Once ingested, LA (omega 6), what can it be converted into? function? (23)
A
- may be converted into certain polyunsaturated acids:
- gamma linolenic acid (GLA)
- eicosatrienoic acid
- eicosatetraenoic acid (AA)
- these compounds affect key cell and physiological processes in the body ranging from cell signaling to inflammation
35
Q
What do omega 3 fatty acids function in? (23)
A
- essential in growth and development throughout human life cycle
- should be included in diet
- inhibit tissue eicosanoid biosynthesis and reduce inflammation
36
Q
Arachidonic acid function?
A
-major constituent of membrane phospholipids and an essential precursor to a number of biological compounds known as eicosanoids that regulate body function, such as immunity, blood clotting, blood pressure
37
Q
eicosanoids function?
A
- derived from 20 carbon AA
- modifications of AA from prostaglandins, the inflammatory hormones that aspirin interferes with
- leukotrienes are produced in the body from AA by the enzyme 5-lipoxygenase
38
Q
Essential fatty acids deficiency side effects?
A
- hemorrhagic and scaly dermatitis
- skin dryness and atrophy
- weakness
- impaired vision
- tingling sensations
- mood swings
- edema
- high blood pressure
- high triglycerides
- hemorrhagic folliculitis
- hemotologic disturbances (sticky platelets)
- immune and mental deficiencies
- impaired growth
39
Q
High omega 6/omega 3 ratio in modern diets? what does it lead to?
A
- modern ratio is 15:1
- excessive omega 6 has been linked with pathogenesis of many diseases, including cardiovascular disease, cancer, inflammatory and autoimmune disease
- a 2:1 ratio has been associated with reduced mortality from cardiovascular disease, suppressed inflammation in patients with rheumatoid arthritis, decreased risk of breast cancer
40
Q
Structure of cis vs trans unsaturated fatty acids? (25)
A
- trans are produced when naturally occurring cis are altered chemically by partial hydrogenation
- after this process, cis is changed to trans
- cis has 2 carbons on the same side of the double bond
- trans has 2 carbons on opposite sides of double bond
- so the trans resembles the linear packing of saturated fatty acids
41
Q
What increases membrane fluidity?
A
- warmth because lipid molecules have more kinetic energy
- more unsaturated fatty acids which prevent lipids from packing close together
42
Q
Nerve transmission relation to membrane fluidity?
A
- nerve transmission relies on ion pumping
- when membranes are not fluid, this interferes with ion channels (transmembrane proteins) and prevents passage of ions
- this is how local anesthetics such as lidocaine work
43
Q
How does cholesterol affect membrane fluidity?
A
- the steroid ring helps to stiffen the membrane, making it less fluid and preventing other lipids from packing tight
- trans fatty acids that are incorporated into the cell membranes create denser membranes that alter the normal functions of the cell
44
Q
Why is fat an essential part of a nutritious diet?
A
- we need a minimum amount in order to provide adequate levels of essential fatty acids and fat soluble vitamins
- during rest and prolonged exercise, fat is our primary source of stored energy for maintaining cell function
45
Q
What effect does reducing saturated and trans fat in our diet have?
A
- consuming saturated and trans fat, they are deposited in cell membranes and replace cis unsaturated fatty acids
- this makes membrane less fluid
- reducing these fats has a cholesterol lowering effect and a decreased risk for cardiovascular disease and obesity
46
Q
What are most of the lipids consumed by humans in the form of?
A
- in the form of triglycerides (triacylglycerols, TG)
- the rest consist of cholesterol, cholesterol esters, free fatty acids, phospholipids
47
Q
Triacylglycerol function?
A
-TG is the major form of fat stored in adipose cells -they are highly concentrated metabolic energy storage (main constituents of vegetable oils and animal fats) because they are anhydrous and exclude water
48
Q
Structure of triglyceride? (28)
A
- TG consists of 3 Carbon glycerol backbone and 3 fatty acids
- glycerol is an alcohol composed of 3 carbon atoms
- each other 3 fatty acids within each TG can be different sizes and can be either saturated or unsaturated
49
Q
order of packing in TG? (29)
A
- each fatty acid in TG can be different sizes and can be either saturated or unsaturated
- saturated fatty acids have a straight configuration and usually pack into a solid crystal at ambient temps
- highly ordered packing of fatty acid chains is disrupted by the presence of cis double bonds
- TG with only saturated fatty acids stack well together to make solid fat at room temp
- TG with monounsaturated fatty acids sandwiched between 2 saturated fatty acids don’t stack well because of the bend, these stay liquid at room temp
50
Q
composition of various fats in butter, vegetable oil, and margarine? (30)
A
-vegetable oil can be partially hydrogenated to more trans fat, doesnt make it any healthier than saturated fats
51
Q
What does a diet high in saturated fat and cholesterol result in?
A
- increased LDL, decreased HDL which promotes cardiovascular disease and cancer growth
- trans fats also raise levels of trigclyeride in blood
- promotes insulin resistance, linked to diabetes, hypertension, and cardiovascular disease
- animal fats and tropical oils high in myristic acid (C14:0) and low in linoleic acid increase cholesterol levels
52
Q
What can oils high in linoleic acid such as grape seed oil, sunflower oil, and safflower oil do for health?
A
-play a significant role in reducing blood cholesterol levels when consumed regularly in diet
53
Q
What is the most important use of lipids in the cells?
A
- formation of membranes
- membranes contain amphipathic with a hydrophobic end and a hydrophilic end
54
Q
What are the two general classes of lipids?
A
- Neutral uncharge lipids (non polar)
- Amphipathic lipids (polar)
55
Q
Neutral uncharged lipids (non polar) examples? (35)
A
- Triacylglycerol (TG)
- cholesterol esters (CE)
57
Q
Further classification of lipids? (33)
A
- further classified based on chemical backbone
- TG and glycerophospholipids (phospholipids) have a backbone of 3 carbon glycerol
- Glcyosphingolipids (glycolipid) and sphingophospholipids (phospholipids) have a backbone of sphingosine
58
Q
Glycerol vs sphingosine backbones? (34)
A
- glycerolipids have glycerol backbone
- sphingolipids have a sphingosine backbone (18C alcohol)
59
Q
Example of Glycerolipids? properties? (37)
A
- Monoacylglycerol (MG- monoglyceride)
- amphipathic (one polar charged end, one uncharged non polar end)
- polar
- membrane lipid
- only one OH group is esterified to a fatty acid
- the other two OH groups are free, giving the structure some polarity
60
Q
Glycerophospholipids? properties? (38)
A
- phospholipids
- amphipathic (polar and non polar ends)
- important part of membrane lipid bilayer of cell
- assist in transporting fat in bloodstream
61
Q
Glycerophospholipid structure? (38)
A
- consist of a glycerol backbone and 2 fatty acids with a phosphate and head group (alcohol: ethanol amine, choline, serine, inositol)
- phosphate group is soluble in water (hydrophilic) giving it its amphipathic property
67
Q
Ceramide structure? (42)
A
- contains sphingosine with a fatty acid joined to it amino group
- sphingomyelin
- glycolipids
68
Q
Sphingomyelin structure? (42)
A
-contains a ceramide and phosphocholine/phosphoethanolamine
69
Q
Glycolipids structure? (42)
A
- or glycosphingolipids
- contain a ceramide and a carbohydrate group (either galactose or glucose)
74
Q
Cholesterol structure? (44)
A
- most common sterol in our diets
- polar lipid with steroid ring system (4 rings)
- hydrophobic but a single OH group allows it to interact with water at a membrane surface, considered amphipathic (polar=unesterified) this OH group can be esterified to a fatty acid to form a cholesterol ester (hydrophobic non polar lipid=esterified)
75
Q
Cholesterol function? (44)
A
- part of every cell membrane, especially neural cells that make up brain, spinal cord, and nerves
- vital to metabolism, situated in the crossroads of several metabolic pathways
- several important sterol compound are synthesized using it including sex and adrenal hormones, bile acids, and vitamin D
77
Q
Cholesterol and related lipids? (45)
A
pic
78
Q
Bile acids structure? where made? (46)
A
- made in the liver peroxisome by cytochrome P450 mediated oxidation of cholesterol
- bile acids have a spacial configuration that gives them a polar side and a non polar side
79
Q
Fat soluble vitamins? (47)
A
- A- retinol
- D- calciferol
- E- alpha tocopherol
- K- phylloquinone, menaquinone
- are absorbed into the intestinal mucosal cells along with the products of lipid digestion
- impaired fat absorption or conditions which alter the proper digestion and absorption of the fat can lead to vitamin deficiency
- excess fat soluble vitamins can lead to toxicity
80
Q
fat soluble vitamin summary? (48,49)
A
both pics
88
Q
What happens to the products of TG digestion by TG lipase? (52)
A
- products of TG digestion (MG and fatty acids) are solubilized into small bile acid micelles
- these micelles deliver MG and fatty acids to intestinal epithelial cells where they are absorbed - within epithelial cells, the fatty acid and MG are reesterified into TG
- TG is packaged into chylomicrons
- chylomicrons are transported out to the lymphatics where they enter the bloodstream
89
Q
Overall process of digestion of fats? (51)
A
- liver produces bile acids
- dietary lipids are emulsified by bile acids in duodenum
- pancreas produces TG lipase, colipase, bicarbonate, cholesteryl esterase, phospholipases
- TG lipase (complex with colipase) breaks down TG in emulsified fat droplet at the surface of the droplet, other enzymes also work
- products of TG digestion (MG and fatty acid) are solubilized in small bile salt micelles
- MG and fatty acids are absorbed in to the intestinal epithelial cells from bile acid micelles
- chylomicrons are formed inside the cell
- chylomicrons are transported out of the cell to the lymphatics and then enter the blood
- products of digestion in small micelles are shuttled over to the brush border
91
Q
Process of bile salts forming micelles? (54)
A
- non polar lipids are emulsified in surrounding aqueous milieu
- bile salts form aggregates of emulsion droplets of lipids
- in the lumen of intestine, pancreatic lipase digest dietary long chain fatty acids to products that amphipathic lipids
- polar lipids are emulsified in surrounding aqueous milieu by amphipathic lipids to form micelles
- amphipathic lipids spontaneously form aggregates to become soluble in water (miscible hydrophilic heads surrounding insoluble hydrophobic tails)
93
Q
Process of biosynthesis of bile acids? where does it occur? (55)
A
- occurs in liver peroxisomes
- first step is hydroxylation of cholesterol to 7alpha-cholesterol by 7alpha-hydroxylase
- eventually, chenocholic acid and cholic acid are the products (2 primary bile acids)
- these products inhibit the first step (product inhibition)
94
Q
Conjugation of bile acids in liver? (57)
A
- prior to secretion, bile acids are conjugated with either glycine or taurine
- this increases water solubility and prevents passive reabsorption once secreted into small intestine - acid groups on bile acids are often converted to salts
- bile salts are a major component of bile
- sodium, calcium, potassium are often used to produce bile salts
- sodium glcyocholate and sodium taurocholate (bile salts)
95
Q
Cholic acid and its relationship to other bile acids? (58)
A
pic
96
Q
chemical structure of the major bile acids found in human bile and feces? (59)
A
pic
100
Q
Recycling of bile acids? (61)
A
- there is a large pool of bile acids in the body (3-5g)
- most are reabsorbed either actively or passively - the majority is recycled as primary or secondary conjugated bile acids by active transport from proximal or distal ileum
- secondary conjugated bile salts happen after flora bacteria dehydroxylate bile salts
- these are taken back to the liver via the portal system and carried on albumin through blood stream - additional bile acids are recycled via passive diffusion after they are deconjugated from amino acids glycine and taurine
101
Q
Excretion of bile acids? (61)
A
-in healthy people, the amount of bile acid synthesized from cholesterol equals the amount of bile salts excreted (.8g/day, 5%)
102
Q
Ways that the sterol ring is eliminated? (64)
A
- they are converted to bile acids, but not reabsorbed and the excreted int feces
- they are secreted as intact cholesterol into bile and then eliminated to feces
103
Q
Bile acid chelators? (64)
A
- some types of dietary fibers, ion exchange resins like cholestyramine, block reabsorption of bile acids
- since more cholesterol is converted to bile acids response, this helps to eliminate significant quantities of cholesterol from the body
104
Q
Cholesterol absorption inhibitors? (64)
A
- class of compounds that prevent the uptake of cholesterol from small intestine into circulatory system
- example: ezetimibe
107
Q
Gastric lipase function? (66)
A
- acid stable lipase degrading short and medium chain fatty acids
- accounts for 30% of total TG hydrolysis
- this initial hydrolysis is slow
- important because some of the water immiscible TGs are converted to products that possess both polar and and non polar groups
111
Q
TG lipase (pancreatic) function? (67)
A
- cuts ester bonds at primary alcohol of TG (1 and 3 position)
- major products are 2-MG and fatty acids
113
Q
Colipase function? (68)
A
- bile salts inhibit lipase
- colipase binds lipase anchoring it at the lipid aqueous phase, bringing it into contact with the oil droplet
- and orienting the enzymes active site toward its substrate
- lipase activity is increased by binding to the colipase
- colipase is secreted as a zymogen, procolipase, which is activated by trypsin in the intestine
114
Q
Cholesteryl esterase function? (69)
A
- degrades cholesteryl esters to cholesterol and one fatty acid
- esterase activity is increased in the presence of bile salts
115
Q
phospholipase function? (70)
A
- degrades phosphatidylcholine in two steps to one free fatty acid and lysophosphatidylcholine
- then to glycerophosphoylcholine and 2 free fatty acids
- phospholipase A2 is secreted as a zymogen and is activated by trypsin in the intestine
- its activity is greatly increased in the presence of bile salts
116
Q
Summary of lipid digestion? (71)
A
pic
118
Q
Lipid digestion in the duodenum? (73)
A
- in the duodenum, relatively large emulsified droplets become coated with bile salts
- lipid droplets contain mostly TGs, cholesterol, CE, PLs, and fat soluble vitamins
- digestive enzymes work at the oil water interface to release free fatty acids and 2-MG at the surface
- crowding occurs at the surfaces due to non polar molecules becoming more polar
- this allows molecules at the surface to pinch off into small micro droplets, called micelles
- micelles carry products of digestion to the microvilli where they are absorbed into intestinal epithelial cells (mixed micelles are smaller and contain products of digestion: free fatty acids, lysophospholipids, 2-MG, cholesterol, fat soluble vitamins)
- the micelles bud off from the large lipid droplets after digestion and move toward the brush border membrane of intestinal mucosal cells where lipids are absorbed
120
Q
Cholecystokinin (CCK) function? (74)
A
- cells in the mucosa of the jejunum and lower duodenum produce a small peptide called CCK
- when partially digested lipids and proteins enter the upper small intestine, CCK acts on the gall bladder and exocrine cells of pancreas, causing them to release bile salts and digestive enzymes respectively
- CCK also decreases gastric motility, resulting in a slower release of gastric contents into small intestine
121
Q
Secretin function? (74)
A
- in response to low pH in the chyme entering the intestine, secretin is released
- causes the pancreas to secrete bicarbonate to neutralize the pH of intestinal contents
122
Q
Where do micelles that are in the intestinal lumen go? (75)
A
- they come into contact with the epithelial cell membranes
- the products of lipid digestion pass out of the micelle through the membrane and into the cell
- in the cell, lipids are resynthesized and packaged with specific proteins into chylomicrons
- chylomicrons enter the lymphatic system and then pass from intestinal lymph ducts to the thoracic duct to vessels supplying lungs
- essential fatty acids are needed for surfactant production in lungs
- dietary fats are also transported to muscles, adipose tissue, and liver
123
Q
what do short and medium chain fatty acids require for absorption? (77)
A
- they do not require bile salts for absorption
- they do not need to be packaged into chylomicrons
- they directly enter the portal blood and are transported to the liver bound to serum albumin
127
Q
Structure and composition of chylomicrons? (79)
A
- chylomicrons are spherical particles consisting of a core of TGs (85%) and cholesterol esters (CE) with a shell of alipoproteins, phospholipids, unesterified cholesterol
- alipoproteins are embedded with their hydrophobic edges oriented toward the core and their hydrophilic edges toward the outside
- the major protein of chylomicron is apoB48
129
Q
Formation of chylomicrons? (81)
A
- TG is produced in the smooth ER of intestinal cells from digestive products, fatty acids and 2-MG
- the protein is synthesized in the rough ER, major protein is apoB48
- assembly of lipoprotein occurs in the Golgi complex
- ApoB organizes the assembly
- picks up Apo A, C, E in plasma
- TG composition resembles dietary intake
- requires phospholipids
131
Q
Further acquisition of protein found in chylomicrons? (82)
A
- newly synthesized chylomicrons (nascent) mature as they receive apoproteins C and E from high density lipoproteins (HDL)
- HDL functions in the transfer of these apoproteins and also in transfer of cholesterol from peripheral tissues to liver
- ApoC also found in VLDL
132
Q
What is the fate of TG in chylomicrons? (83)
A
- TG components of chylomicrons (and VLDLs) are hydrolyzed to free fatty acids and glycerol in the capillaries of adipose tissue and skeletal muscle by the action of lipoprotein lipase
- free fatty acids are then absorbed by cells and the glycerol is returned via blood to the liver (and kidneys)
- glycerol is converted to glycolytic intermediate DHAP
- chylomicrons circulate through blood where they are delivered to a tissue that needs lipids
- within lumen of capillaries in the blood stream, TGs are broken down by lipoprotein lipase to fatty acid and glycerol
- this enzyme is used mostly by adipocytes and muscle cells
- it is secreted and associated with the luminal surface of endothelial cells of capillary walls of most tissues
- high insulin induces increased LPL
- ApoC2 activates LPL
135
Q
chylomicron summary? (83)
A
- chylomicrons are synthesized and packaged in intestinal epithelial cells, secreted into lymph, pass into the blood, and become mature chylomicrons
- on capillary walls, lipoprotein lipase (LPL), activated by ApoC, digests the TG of chylomicrons to fatty acids and glycerol
- fatty acids are oxidized by cells which need them or stored in adipose tissue as TGs
- remnants of chylomicrons are taken up by liver by receptor mediated endocytosis
- lysosomal enzymes digest the remnants, releasing products to be used by liver
