Chapter 5 - Lipids: Triglycerides, phospholipids, and

Lipid

• the chemical term for fat

• contribute texture, flavor, and aroma to foods

• contain 9kcal per gram

• american diet contains 34% of its energy from it

Sources of fat

cheddar cheese, bran muffin, eggs, beef, salmon, croissant, canola oil, almonds, sunflower seeds, olive oil

Triglycerides

major form of lipid in food and in the body; consists of three fatty acids attached to a glycerol molecules

Monoglyceride

only one fatty acid is attached to the glycerol

Diglyceride

only two fatty acids are attached to the glycerol

Short-chain fatty acids

have fewer than 6 carbons and remain liquid at colder temperatures; ex. milk

Carbon chains of fatty acids

vary in length from a few to 20 or more carbons

Medium-chain fatty acids

range from 6 to 12 carbons and solidify when chilled, but a liquid at room temperature; ex. coconut oil

Long-chain fatty acids

containing between 14 to 22 carbons, are usually solid at room temperature; ex. beef fat

Saturated fatty acids

• contains carbons in a chain that are bound to two hydrogens

• most animal fats and tropical oil contain this

• when exposed to oxygen, the damage is called rancidity

Unsaturated fatty acids

• contains some carbons that are not saturated with hydrogen

• the essential fatty acids omega-3 and omega-6 are this

• contain monounsaturated and polysaturated fatty acids

Trans fatty acids

• can be creating by hydrogenation, which causes some double bonds to become saturated

• have been shown to raise blood cholesterol levels and increase the risk of heart disease

Phospholipids

lipids attached to a phosphate group

Phosphoglycerides

• major class of phospholipids

• lecithin is a type

• acts as emulsifiers

• form a lipid bilayer in cell membranes, helping to regulated what can pass into and out of a cell

Sterols

• a type of lipid found in plants and animals

• do not dissolve well in water

• can help reduce cholesterol in the body

Cholesterol

• a type of sterol found only in animals

• more than 90% of it in the body is found in cell membrane

• diets high in this can increase the risk of heart disease

Sources of cholesterol

eggs, beef liver, salmon, chicken breast

Lipoproteins

• are transport particles for water-insoluble lipids

• are created by combining water insoluble lipids, phospholipids, and porteins

• help transport triglycerides, cholesterol, and fat-soluble vitamins from the small intestine and stored lipids from the liver

Chylomicrons

• a combination of diet-derived triglycerides, cholesterol, phospholipids, and a small amount of protein

• helps to transport long-chain fatty acids into the lymphatic system and into the blood stream without passing through the liver

• deliver triglycerides to the body’s cells

Liver

major lipids producing organ in the body

Very Low-density lipoproteins (VLDLs)

triglyceride produced in the liver incorporated into entities called vldls; transport lipids out of the liver and deliver them to cells in the body

Lipoprotein lipase

a enzyme that removes triglycerides from VLDLs, creating intermediate density lipoproteins (IDLs)

Low density lipoproteins (LDLs)

• contain less triglyceride and more cholesterol than VLDLs and deliver cholesterol to the cells

• if the amount in the blood exceeds the amount that can be used by the cells, it results to high levels

• high levels of this in the blood have been associated with an increased risk for heart disease

High density lipoproteins (HDLs)

• reverse cholesterol transport where the cholesterol is returned to the liver to be eliminated from the body

• high levels in the blood can help prevent cholesterol from depositing int he artery walls

• high levels can reduce heart disease risk

Adipose tissue

• stores the lipids in the body that are triglycerides

• deposits of this tissue help to define body shape, provide stored energy, insulated the bod from temperature changes, protect internal organs against physical shock

Lipids functions in the body

• important for lubricating body surfaces, such as the mucous membranes of the eyes

• cholesterol is used to make several hormones, including sex hormones and cortisol

• polyunsaturated fatty acids help to regulate blood pressure and blood clotting

Essential fatty acids

important for growth, skin integrity, fertility, and the structure and function of the cell membranes

Eicosanoids

made from omega-3 and omega-6 fatty acids; help regulated blood clotting, blood pressure, and immune function

Atherosclerosis

a disease in which lipids and fibrous materials are deposited in artery walls