Lipids 1

what is the definition of a lipid

A soluble in organic solvents

what are 3 examples of a lipid

Ether, Benzene, Chloroform

what are 3 major classes of lipids that are inportant in nutrition

-Fatty acids

-Mono-di- and triacylglycerols

-sterols

what are some other examples of lipids

-waxes

-Resins

-Essential oils

what is a Fatty acid

Carboxylic acid with hydrocarbon chains between 4- 36 carbons

what is a saturated Fatty acid

No double bonds

What is a Unsaturated Fatty Acid

it has one or more double bonds

Palmitic acid

(16:0)

16 carbons

0 double bonds

Oleic acid

(18:1 cis-9)

18 carbons

1 double bond in cis cinfiguration at c9

palmitic acid

Oleic acid

what is the lipid number

14:0

what is the lipid number

16:1 cis-9

stearic acid

C18:0

Linoleic Acid

C18:2

Linolenic Acid

C18:3

Omega-3

Double bond at 3rd carbon from end of chain

What is an example of a omega-3

a-linolenic acid

(18:3 (n-3)) OR 18:3 all cis 9,12,15

what is this

a-Linolenic acid 18:3 (n-3)

what is a conjugated linoleic acid

family of 28 isomers of linoleic acids

-has alternating double bonds and single bonds

-can be cis or trans

what are intermediates of biohydrogenation in the rumen

conjugated linoleic acid

Rumenic acid

18:2 cis-9, tans-11

what is a monoacylglycerol

1FA

what is a diacylglycerol

2FA

what is a triacylglycerol

3FA

what are majior forma of fat storage in animals (in adipocyted and seeds)

Mono-di- and triacylglycerols

what do sterols contain

a fused carbon ring

what is the most abundant sterol in animal tissue

Cholesterol

what is cholesterol a component of

cell membranes

what are some other examples of sterols

-bile acid

-progesterone

-estrogen

What is the function of Lipids

Great source of energy

what are some chracteristics of lipids

-calorically dense

-High digestible (>80%)

Are a-linolenic and linoleic acid essential explain

Yes they are essential

• cannot be synthesized, animals lack desaturase enzymes to form unsaturated bonds

what happens with deficiency in a-linolenic and linoleic acid

can cause dermatitis, skin lesions, poor growth, reproductive failure

what do a-linolenic and linoleic serve as

as precursor for longer and more unsaturated polyunsaturated fatty acids (PUFA)

what is conditionally essential if not enough a-linolenic and linoleic acid for synthesis

EPA, DHA, AA( arachidonic acid)

what is the most abundant n-3 PUFA in brain and retina

DHA

Which ones are precursours of the signaling molecules eicosanoids

EPA & AA

what is specially about cats

AA is non-conditionally essential (need AA in diet)

• canot be synthesized from linoleic acid

is conjugated linoleic acid essential

not really

why is conjugated linoleic acid (CLA) not essentail but important

• in animals it is protective benefit against cancer, diabetes,obesity

• In humans, benefits are smaller or inconclusive

where does digestion begin

in small intestine

where does bile enter and what it do

enters duodenum from gallbladder and emulsifies lipids

• decreases lipid droplet size

• increases SA for enzymatic digestion

-These solve problem that enzymes are soluble in water but lipid is not

how does digestion continue

with hydrolysis of triacylglycerols

• involves lipases released by pancrease and small intestine

What does digestion and absorption of lipids yield

Free FA

• Glycerol

• Monoacylglycerols

what happens with micells in digestion and absorption of lipids

Free FA and monoacylglycerols packed into miclells

what other lipids do micells include

-Cholesterol

-Fat soluble vitamins

-Bile salts

where does absorbtion of lipids happen

In Jejunum and ileum

what happens during absorption of lipids

FA and monoacyglycerol move out of micelles

-Then absorbed by diffusion (can cross through membrane without transporter)

where does transport and depsition of lipids take place

in small intestine (enterocytes)

What is formed in small intestine in Transport and deposition

Triacylglycerols are reformed

( FA re-esterify to glycerol or monocylglycerols)

-Lipoproteins (chylomicrons) are formed

(triacylglycerols, cholesterols and phospholipids are combined with apolipoproteins)

What is the lymphatic system and what is it part of

it is part of transport and deposition

• and is when chylomicrons move from enterocytes into lymphatic systems

after the lymphatic system where do chylomicrons go and what happens

into bloodstream

• where lipoprotein lipase converts triacylglycerols to FA and glycerol which occurs on endothelial surface of capillaries

what is peripheral tissue

part of tranport and depostition of lipids

-FA enters and oxidized/re esterified for storage

what are the main recipients of Peripheral tissues

• skeletal muscle, adipose tissue, and mammary gland main recipients

what does the liver do in terms of Transport and deposition of lipids

takes up remnants of chylomicrons

-Mostly depleted of FA but still contain cholesterol and apolipoprotein

what is a summary of how lipids are transported and deposition

1) small intestine

2) lymphatic system

3) bloodstream

4) peripheral tissue

5) liver

what is the carrier of lipids

chylomicrons (lipo protein)

what pathway is the transport and depostion of lipids an example of

Exogenous pathway (coming from diet than absorbed)

what is the first step in the Endogenous pathway

Liver

-excess FA re-esterifies into triacylglycerols(excess when to much for oxidation or ketone formation

-Triacylglycerold packed with apolipoproteins into very low density lipoprotein (VLDL)

-VLDL exported into blood

what is teh second step of the endogenous pathway

Blood

• VLDL enters the blood from liver

• FA released by lipoprotein lipase (same as chylomicrons)

what is the 3rd step of endogenous pathway of lipids

Peripheral tissues

• FA taken up(especially by adipose tissue)

what is the 4th step of the endogenous pathway

Blood(again)

-Low density lipoproetein (LDL) formed from VLDL (afetr loss FA)

-LDL releases cholesterol

what is the 5th step of the endogenous pathway of lipids

Peripheral tissue (again)

-Cholesterol taken up

what is the reverse cholesterol pathway

high density lipoprotein(HDL) export lipid from peripheral tissue back to liver

what is LDL

low density lipoprotein

-”bad cholesterol” because correlated with high rates of atherosclerosis

-Related to export of cholesterol from liver to peripheral tissues

what is HDL

high density lipoprotein

-”good cholesterol” correlated eith low rates of atherosclerosis

-related to export of lipid from peripheral tissues to liver

how much triglycerides do chylomicrons have

85-95%

how much triglycerides do HDL have

2-7%

how much triglycerides do LDL have

4-8%

what are the 3 diffrent pathways FA are absorbed through the intestine and tranposted to tissues

Exogenous pathway

-Endogenous pathway

-reverse cholesterol transport