Nutrition Chapter 6: Lipids, Triglycerides, Phospholipids and steroids

LIpases

enzymes that break down lipids

homocysteinuria

a group of conditions caused by gene mutations that cause homocysteine to accumulate in the blood

Cardiovascular disease (CVD)

a group of diseases that affect the heart and blood vessels; includes coronary artery disease, stroke and disease of the blood vessels.

Eicosanoids

a group of long-chain acids with hormone like functions

Embolus

a thrombus or part of a plaque that breaks free and travels through the bloodstream

phospholipid

a type of lipid needed to make cell membranes and for proper functioning of nerve cells;chemically similar to a triglyceride except that one of the fatty acids is replaced by a chemical group that contains phosphorus. -partially water soluble

chylomicron

a type of lipoprotein formed in enterocytes to transport lipids through the bloodstream.

where are plant sterols and stanols found?

grains fruits vegetables nuts seeds legumes

Cis fatty acids

most naturally occurring unsaturated fatty acids hydrogen atoms of the double-bonded carbons are on same side of hydrocarbons chain

Stroke

occurs when a clot blocks an artery in the brain; brain cells that are nourished by the vessel die.

VLDLs

shuttle lipids to adipose tissue cells (cells that store triglycerides)

where does the majority of lipid absorption occur?

small intestine

Enterohepatic circulation

the process that recycles bile salts in the body which is incorporated into new bile

How are long-chain fatty acids absorbed?

requires additional steps. they are packed together with bile, cholesterol and fat-soluble vitamins in micelles. -then when micelles comes close to villi, there contents diffuse into absorptive cells

AHA recommendations for reducing the risk of developing CVD:

sat fat <10% of total kcals limit trans fat intake omega-6 fatty acids 5-10% total energy intake 8 oz of cold-water fatty fish/week limiting consumption of animal foods

Lymphatic system's role

transports chylomicrons to the thoracic duct; where it will enter the bloodstream at the left subclavian vein and circulate through the body

cascade of events following injury of arterial lining:

injured arterial lining becomes inflamed> white blood cells become laden with oxidized LDL particles> arterial plaques (fatty buildup in the artery) form interference of circulation > clots more likely to form

Plants containing soluble fiber

interfere with cholesterol and bile absorption which helps reduce blood cholesterol levels

Oil

less dense than water, so it will rise to the top of a solution

medium-chain fatty acids have how many carbons?

6-12

AI's for alpha-linolenic acid

1.6g/day for men 1.1 g/day for females

long-chain fatty acids have how many carbons?

14-24

olive oil

a rich source of MUFAs

Atherosclerosis

a long-term disease process in which plaque builds up inside arterial walls

Carotid Arteries

convey blood to the brain **atherosclerosis in these arteries can result in reduced blood flow to the brain and increase the risk of stroke

lipid storage diseases

genetic conditions that cause lipid accumulation in cells damaging tissues.

Gallstones

hard particles that can accumulate in the gallbladder or become lodges in one of the ducts carrying bile from the gallbladder to the small intestine

Cholecystokinin (CKK)

hormone that stimulates the gallbladder to release bile and the pancreas to secrete digestive juices

two parts of a phospholipid

hydrophobic end (will not dissolve in water) hydrophilic end (water loving)

Pancreatic Lipase

the digestive enzyme that removes two fatty acids from each triglyceride molecule

Omega

the end of a fatty acid containing a methyl group

hydrogenation

the food manufacturing process that adds hydrogen atoms to liquid vegetable oil, forming trans fat -these foods can be stored for longer because they are less likely to undergo oxidation -raise "bad" cholesterol in the blood -increases risk of heart disease

After absorption:

the fragments are reassembled into triglycerides and phospholipids.

Fat malabsorption

the impaired fat absorption; symptoms include diarrhea, steatorrhea and rapid weight loss

Gaucher disease

the most common lipid storage disease; caused by a deficiency of the enzyme glucocerebrosidase

steatorrhea

the presence of lipid in the stool -can occur if gallbladder is diseased or removed

lipoproteins

play roles in the development of atherosclerosis

hydrocarbon chain

a chain of carbon atoms bonded to each other and to hydrogen atoms.

Prostaglandins

a class of eicosanoids that produce a variety of important effects in the body.

Lipids

a class of nutrients that do not dissolve in water; triglycerides, phospholipids and sterols they dissolve in organic substances

Stearic acid

an 18-carbon saturated fatty acid

homocysteine

an amino acid that may play a role in the development of atherosclerosis

Lipoprotein lipase

an enzyme in capillary walls that breaks down the triglycerides -nearby cells pick up fatty acid s and glycerol to use for energy

carboxylic acid

an organic molecule with a carboxyl group

trans fats

are unsaturated fatty acids that have a double-bond hydrogen atoms of the double bonded carbons are on opposite sides of hydrocarbon chain

will cause HDL levels to decrease

blood concentrations of triglycerides increasing (this may contribute to CVD)

how are fatty acids identified?

by number of carbon atoms bonded and the type of bond between the carbon atoms

Plant sterols and stanols

chemicals found in plants that are structurally similar to cholesterol (these in mass, can help lower Cholesterol levels)

Bile Salts

components of bile; aid in lipid digestion and emulsification

how are short- and medium-chain fatty acids absorbed?

diffuse into the absorptive cells of the villi to enter into the capillary network

other dietary recommendations:

eat soft or liquid margarines trim away fat from meat consume fat-free milk eat food rich in fiber consume less alcohol engage in moderate-intensity physical activity 5 days/week

Where is cholesterol found?

egg yolk liver meat poultry dairy products

Essential fatty acids

fatty acids that must be supplied by the diet; linoleic and alpha-linolenic acid are both essential fatty acids

Thrombus

fixed bunch of clots that remain in place and disrupt blood flow. (partially closes off artery's lumen) **if in heart, person experiences bouts of chest pain.

Myocardial infarction

heart attack-occurs when a thrombus completely blocks blood flow to the heart muscle

Sterols

lipids that have a more chemically complex structure than a triglyceride or fatty acid.

Liquid corn oil

contains a greater proportion of unsaturated than saturated fatty acids.

fat in beef and dairy products

contains more saturated than unsaturated fatty acids

processed foods and margarines

contribute to the largest amounts of trans fats

chronic inflammation can lead to

development of CVD

LDL

"bad" cholesterol conveys lipid to tissue

HDL

"good" cholesterol does not contribute to plaque formation

AI's for linoleic acid

17 g/day for men 12 g/day for women

AMDR for fat =

20-30%

Oxidized LDL

LDL that has ben damaged by free radicals and contributes to atherosclerosis

Arteriosclerosis

a condition that results from plaque build up inside arterial walls and is characterized by loss of arterial flexibility

Dietary Guidelines suggestions on foods:

you should emphasize foods that are rich in polyunsaturated and monounsaturated fatty acids (ie> fish, nuts, and vegetable oil)

Major functions of lipids in the body:

1. providing and storing energy 2. forming and maintaining cell membranes 3. producing steroid hormones 4. insulating the body against cold temperatures 5. cushioning the body against bumps and blows 6. forming body contours 7. absorbing fat-soluble vitamins and phytochemicals

short-chain fatty acids have how many carbons?

2-4

How much does fat contribute to the average American;s daily energy intake (DEI)

33%

essential fatty acids that are precursors to eicosanoids:

Arachidonic acid (AA) Eicosapentaenoic acid Docosahexaenoic acid

Saturated fatty acid (SFA)

a fatty acid that has each carbon atom within the chain filled with hydrogen atoms.

Monounsaturated fatty acids (MUFA)

a fatty acid that has one double bond within the carbon chain

Polyunsaturated (PUFA)

a fatty acid that has two or more double bonds within the carbon chain

Unsaturated fatty acid

a fatty acid that is missing hydrogen atoms and has one or more double-bonds within the carbon chain

Fatty acid

a hydrocarbon chain bound in lipids; one end of the chain forms a carboxylic acid, and one end forms a methyl group.

Cholesterol

a lipid found in animal foods; precursor for steroid hormones, bole and vitamin D

Monoglyceride

a lipid that has one fatty acid attached to a three-carbon compound called glycerol

Triglyceride

a lipid that has three fatty acids attached to a three-carbon compound called glycerol -comprises 95% of lipids in food and body -most contain a mixture of unsaturated and saturated fatty acids; with one type of fatty acid predominating

Diglyceride

a lipid that has two fatty acid attached to three-carbon compound called glycerol

Very-low-density lipoprotein (VLDL)

a lipoprotein made in liver that carries much of the triglycerides in the bloodstream

Low-density lipoprotein (LDL)

a lipoprotein that carries cholesterol into tissue. elevated levels is strongly linked to increased risk of CVD.

High-density lipoprotein (HDL)

a lipoprotein that transports cholesterol away from the tissues to the liver to be eliminated. low levels is linked to increased risk of CVD.

High-sensitivity C-reactive protein (hs-CRP)

a portion produced primarily by the liver in response to inflammation; a marker of CVD

Lipoprotein profile

a series of blood tests to evaluate total cholesterol, HDL and LDL and triglyceride levels. this helps determine a person's risk for developing atherosclerosis

emulsifier

a substance that helps water soluble and water insoluble compounds mix together (a phospholipid is an example of this because it has both a hydro-phobic & philic end )

Cholecyctetomy

a surgery to remove a diseased gallbladder

Glycerol

a three-carbon alcohol that forms the "backbone" of fatty acids

omega-6 fatty acid

a type of polyunsaturated fatty acid with the first double bond at the sixth carbon from the omega end of the molecule (linoleic acid)

Omega-3 fatty acid

a type of polyunsaturated fatty acid with the first double bond at the third carbon from the omega end of the molecule (alpha-linolenic acid)

choline

a water-soluble vitamin like compound and is a component of lecithin. -it is found in egg yolk, liver, wheat germ, parent butter and soybeans (used to form acetylcholine)

Oleic Acid

an 18-carbon monounsaturated fatty acid

Alpha-linolenic acid

an 18-carbon polyunsaturated fatty acid with 18-double bonds; an essential fatty acid.

Linoleic acid

an 18-carbon polyunsaturated fatty acid with two double bonds; an essential fatty acid