Chapter 5: The Lipids

list the functions of lipids in the body:

1)provide energy 2)insulate against temperature extremes, 3)protect against shock, and 4) help the body use carbohydrate and protein efficiently

Dietary Requirements: Dri and 2005 dietary guidelines

20 to 35 percent of the daily energy from fat. Less than 10% from saturated fat and less than 300 milligrams from cholesterol.

what is the RDA for sterols?

300 miligrams per day? on page 141

Lipids and health: cancer

Although cancer is not caused by dietary fats, they promote cancer once it has arisen.

explain the DRI for fat, saturated fat and essential fatty acids

DRI for fat: 20 to 35% saturated fat: less than 10% of kcal from sat fat essential fatty acids:basically the 20 to 35%

Lipids and health: cardiovascular disease

Elevated LDL is a major risk factor for cardio vascular disease. trans fats, saturated fats and solid fats clog arteries, increase LDL and lower HDL.

what are the functions of cholesterol in the body? is it essential? what is the recommended dietary intake? what foods are rich in cholesterol?

Functions of cholesterol include bile acids, sex hormones, adrenal hormones and vitamin d. recommended intake is less than 300 miligrams. Meats, eggs, seafood and poultry, and dairy contain cholesterol. Body does need cholesterol, but it makes its own so it doesn't need outside cholesterol.

cholesterol

Good cholesterol refers to the way the body transports cholesterol in the blood. 90 percent of the cholesterol is found in cells. the body makes and uses cholesterol.

lipoprotein lipase:

Lipoprotein lipase helps with lipid metabolism. it hydrolyzes triglycerides from circulating lipoproteins, releasing fatty acids, diglycerides, and monoglycerides into the adipose cells. Then they become reassembled inside the cell.

what are lipoproteins? identify the types found in the body and their functions. (4)

Lipoproteins are clusters of lipids associated with proteins that serve as transport vehicles for lipids in the lymph and blood. 1)chylomicrons: transport triglycerides from intestinal cells to rest of body) 2)VLDL: made by liver cells (lipid synthesis), transports lipids to various parts of body. 3)LDL: circulate thruout body for energy for cells of all tissues.(implicated in heart disease) 4)HDL: takes cholesterol from body back to liver.

Bile

The bile enters SI from the gall bladder, it emulsifies fat. most bile is reabsorbed into SI and recycled. Some bile is trapped by dietary fibers in the large intestine and excreted. The proper excretion of bile reduces blood cholesterol.

triglycerides and fatty acids: degree of saturation

The degree of unsaturation influences the firmness of fats at room temperature. Most polyunsaturated fats vegetable oils are liquid at room tempreature and the more saturated animal fats are soild. saturated fats spoil less quickly

Digestion of the tryglyceride

The enzymes turn the tryglyceride into a monoglyceride. occasionally enzymes remove all three fatty acids leaving a free molecule of glycerol.

what are mono and polyunsaturated fatty acids? how do they differ from saturated fatty acids? what foods are sources of each type of unsaturated fatty acids?

They are unsaturated fatty acids which means they are missing hydrogens and have double bonds. They differ from saturated fatty acids because they are healthier, become rotten quicker. Example of monounsaturated fats are avocado, buts, oils (canola), olives. Example of polyunsaturated fats are mayo, seeds, fish, oil (flaxseed)

name two essential fatty acids needed by the body and the health benefits of each. List foods that are good sources of each.

Two essential fatty acids are omega 3 and omega 6. omega 3 acids are essential for normal growth, visual activity, and cognitive development. taking omega 3's will help reduce inflammation, prevents blood clots, lower blood pressure. omega 6 plays a role in brain function

lipid bilayer

a cell membrane is made up of phospholipids called a bilayer. The fatty acid tails orient themselves away from the watery fluid and the glycerol and phosphate heads are attracted to the watery fluids.

Phospholipid

a compound similar to a triglyceride but having a phosphate and choline (or another nitrogen-containing compound) in place of one of the fatty acids

what are saturated fatty acids? what foods are high in saturated fats?

a fatty acid carrying the maximum possible number of hydrogen atom. A saturated fat is composed of triglyceride in which most of the fatty acids are saturated. cocoa butter, palm oil, bacon, butter, cheese, coconut, chocolate, ice cream. most animal fats are high in saturated fat. steraic acid is a saturated fatty acid

saturated fatty acid

a fatty acid carrying the maximum possible number of hydrogen atoms. a saturated fat is composed of triglyceride in which most of the fatty acids are saturated.

lecithin

a phospholipid that is a constituent of the cell membrane. Because it is soluable in both water and fat, they can help fat soluble substances, including vitamins and hormones, to pass easily in and out of cells.

atheroscelerosis

a type of artery disease characterized by plaques (accumulations of cholesterol containing material) on the inner walls of the arteries. it causes heart attacks and strokes.

hydrophilic

allows them to dissolve in water

Lipid digestion in SI

bile brings fat into the water by surrounding it, thus it is emulsified. After emulsification more fat is exposed to enzymes thus letting fat digestion to be more efficient.

Fatty acids

can be saturated or unsaturated. OR organic compounds composed of a carbon chain with hydrogens attached and an acid group (COOH) at one end and a methyl group (CH3) at the other end.

what other health conditions besides cardiovascular disease are linked to dietary fat consumption?

cancer and obesity

lipid transport from the small intestine through chylomicrons

cells all over the body remove triglycerides from the chylomicrons as they pass by.

exogenous

cholesterol from outside the body (from foods)

Sterols

compounds containing four ring carbon structure with side chains attached. Most well known sterol is chelosterol.

Triglyceride

contains one molecule of glycerol and three fatty acids

roles of phospholipids

emulsifiers, helps with absorption in and out of cell,

glycerol

every triglyceride contains one molecule of glycerol and three fatty acids.

Lipid digestion in the stomach

fat floats at the top of water as the stomach contracts and turns food into chyme pushing it through the pyloric sphincter. Little pieces of fat is exposed to the gastric lipase enzyme, then most goes to SI.

Lipids and health: obesity

fat has more kcal per gram, thus it can can weight gain if someone is not active. cutting fat could be good for losing weight, however if it is replaced with carbohydrates then it doesn't really matter.

digestion of phospholipids

fatty acids are removed by hydrolysis.

essential fatty acids

fatty acids that the body requires but cannot make, and so must be obtained from the diet; both linoleic acid (omega 6) and linolenic acid (omega 3) are essential fatty acids

Emulsifier

food industry used phospholipids as an emulsifier. OR a substance with both water soluble and fat soluble portions that promote the mixing of oils and fats in watery solutions.

trans fatty acids

hydrogens next to the double bonds are on opposite sides of the carbon chain. Hydrogenation produces trans fatty acids.

lipid absorption of large molecules

larger molecules such as monoglycerides and long chain fatty acids are emulsified by bile (bile surrounds fatty acid) forming micelles. The micelles diffuse into the intestinal cells where the monoglycerides and long chain fatty acids reassemble into new tryglycerides.

Define the term lipid and describe the types of lipids that are important in nurtition

lipids are composed of carbon, hydrogen and oxygen. books defn: a family of compounds that includes triglycerides, phospholipids and sterols. they are insoluable in water. Important in nutrition: Polyunsaturated fatty acids (omega 3 and omega 6) and monounsaturated fats.

Transport from the liver: VLDL

lipids made in the liver and those collected from chylomicron remnants are packaged with proteins as a vldl (Very low density lipo protein) and shipped to other parts of the body.

Transport from the liver: HDL

made by liver to remove cholesterol from the body, carry it to liver for recycling or disposal.

endogenous

made inside the body

Unsaturated fatty acids

may have one or more points of unsaturation - that is, they may be monounsaturated or polyunsaturated. a fatty acid that lacks hydrogen atoms and has at least one double bond between carbons. an unsaturated fat is composed of triglycerides in which most of the fatty acids are unsaturated.

Polyunsaturated fatty acids

omega 3 (linolenic acid) fatty acids and omega 6 (linoleic) fatty acids. Both of these the body cannot make. Vegetable oils, which are liquid at room tempreature.

Sources of cholesterol

only those from animals contain significant amounts of cholesterol. (meats, eggs, seafood, poultry and dairy products.)

explain hydrogenation and why lipids are hydrogenated during food manufacturing. How are hydrogenated fats identified in food products

points of unsaturation are saturated by adding hydrogen molecules. Hydrogenation protects against oxidation (prolonging shelflife) by making polyunsaturated fats more saturated. it also alters the texture of foods by making them more solid. If something says that it is a trans fatty acid then it has probably been hydrogenated, because very little trans fat naturally exists naturally.

what are the Lipid functions in the body (5)

provide energy (fat provides 9kcal) which is extremely efficient storage energy, insulate against extreme temperatures (layer of fat insulates the body from extreme temp), protect against shock (cushion for bones and vital organs), maintain cell membranes. Lastly they are a carrier of fat soluble vitamins

what are some of the known risk factors for cardiovascular disease? Describe how the different types of fat affect risk factors for cardiovascular disease

saturated fats increase LDL and LDL increases the risk of heart disease. saturated fats also contribute to heart disease by promoting blood clotting. Trans fat and heart disease also have a negative association.

Functions of sterol

serves as the starting material for the synthesis of bile acids, sex hormones, adrenal hormones, and vitamin D. It is also structural component of cell membranes.

Lipid absorption of small molecules

small molecules such as glycerol and short/medium chained fatty acids can easily diffuse into the intestinal cells/blood stream.

lipoproteins

solve the bodys challenge of transporting fat through the watery bloodstream. one of these clusters of lipids is called chylomicrons. there are four main types of lipoproteins.

Hydrogenation

some or all of the points of unsaturation are saturated by adding hydrogen molecules. it protects against oxidation (thereby prolonging shelflife) by polyunsaturated fats more saturated. It also alters the texture of foods by making liquid vegetable oils more solid.

adipose tissue:

the body's fat tissue; consists of masses of triglyceride-storing cells.

What happens if the carbon chain is shorter

the softer it is at room temperature.

micelles

tiny spherical complexes of emulsified fat that arise during digestion. fat is surrounded by bile.

what is the goal of fat digestion

to dismantle triglycerides into small molecules the body can absorb and use (monoglycerides, fatty acids, and glycerol)

chylomicrons

transport vehicle in the intestinal cells. they are packed with tryglyceride, other lipids and protein. They then are released into the lymphatic system. At the thoracic duct near heart they are absorbed into blood stream. they are the largest and lease dense.

hydrophobic

water fearing

lipid digestion in the small intestine

when fat enters the SI, CCK (hormone cholecystokinin) gets released which signals the gallbladder to release its stores of bile. The bile pair up with amino acid. The amino acid end if hydrophilic and the sterol end is hydrophobic. Thus the biles acts as an emulsifier. Then they encounter lipase enzymes from the pancreas and SI.

Transport from the liver: LDL

when the VLDL becomes smaller and smaller as it moves throughout the body, cholesterol becomes the main lipid and lipoproteins becomes smaller and more dense. Thus becoming an LDL: Low density lipoprotein: loaded with cholesterol, but containing relatively few triglycerides. The functions of LDL are use triglycerides, chol, and phospholipids to make energy, hormones and build membranes.