NU 250 Exam 1 (Chapter 3: Lipids)

What is the function of Cholesterol (Sterol)?

(builds) a. required for normal body function and can be synthesized in the liver. it is a nonessential compound b. precursor to steroid hormones c. formation of bile acids d. component of brain and nerve tissue; and cell membranes e. cholesterol occurs naturally in animal foods but not plant foods f. food sources contain cholesterol: egg yolk, meat, whole milk, and cheese, liver and organ meats g. recommended intake is no more than 300mg/day

What is the end product of lipid digestion?

Free fatty acids and monoglycerides

What are the major food sources of saturated fats, polyunsaturated fats, and monounsaturated fats?

1. Saturated Fats: Primary sources include animals, including beef, poultry, pork, lamb, luncheon meat; egg yolks; and dairy products (milk, butter, and cheeses); only plant source palm and coconut oils (often called tropical oils) and cocoa butter. 2. Monounsaturated fatty acid (MUFA): A fatty acid containing one point of unsaturation. a. Primary sources include olive oil, peanuts (peanuts and peanut oil), avocado, and canola oil 3. Polyunsaturated fatty acid (PUFA): A fatty acid with two or more points of unsaturation. a. Sources: vegetable oils (corn, safflower, wheat germ, canola, sesame, and sunflower), fish, and margarine

Identify the (3) main classes of lipids

1. Triglycerides: the chief form of fat in foods and body fat; made up of (3) units known as fatty acids and a backbone unit of glycerol. 2. Phospholipids: Similar to triglycerides, but has a phosphorus-containing acid in place of one of the fatty acids. Phospholipids are present in all cell membranes. 3. Sterols: lipids that have a structure similar to that of cholesterol

What is the function of phospholipids?

A. form important parts of cell membranes B. They form a double-layered sheet (lipid bilayer)- it orients the water- soluble, phosphate- containing "head" towards the aqueous (water) environments inside and outside the cell, ad orients the fatty acid "tail" to form the lipid center of the membrane. C. Phospholipids act as emulsifiers (compounds that enable water and fats to mix. D. Bile contains phospholipids as well as cholesterol which aids in the absorption of fats in the body E. The body produces all the phospholipids it needs- they are not essential components of the diet Example: Lecithin is a common example of a phospholipid, and it is often used an an additive in many foods for the purpose of emulsification (salad dressings (lecithin keeps the oil and vinegar from separating) eggs act as emulsifiers- preventing fat and water from separating in baking batter)

How is lipid absorbed into the blood stream?

Absorption and Transport into Blood. The major products of lipid digestion - fatty acids and 2-monoglycerides - enter the enterocyte by simple diffusion across the plasma membrane. A considerable fraction of the fatty acids also enter the enterocyte via a specific fatty acid transporter protein in the membrane.

Recommended intakes of fat (AMDR)?

Acceptable Macronutrient Distribution Range (AMDR) for fat: 20% to 35% of total kcalories

State the important functions of body lipids

Body Lipids: A. Storage source of energy -However, fatty acids are the preferred fuel of the heart muscle. B. Thermal insulation - layer of fat just beneath the skin assists in temperature regulation. C. Protection of vital organs from damage. D. Transmission of nerve impulses - lipids surround nerve fibers. Form membrane structure - help transport nutrients, metabolites, and waste in and out of cells. E. Carrier of fat-soluble vitamins to the cells. F. Lipoproteins - carries fat soluble material to and from liver. G. Precursors of other substances.

Differentiate between a saturated fatty acid and an unsaturated fatty acid as to chemical, structure and food sources.

Saturated fatty acids contain fatty acids that carry the maximum possible number of hydrogen atoms (having no points of unsaturation). Unsaturated fatty acids is a triglyceride that contains one or more unsaturated fatty acids.

Identify the essential fatty acids - Omega-6 (food sources) and Omega-3 (food sources); what are their functions; and food sources for ALA, DHA, and EPA.

Two essential polyunsaturated fatty acids for humans: 1. Linoleic Acid (omega-6) (Good source: vegetable oils) 2. Alpha-linolenic acid (omega-3) (Good Source: nuts esp. walnuts, flaxseeds) Two other important types of omega-3's: 1. Eicosapentaenoic acid (EPA) 2. Docosahexaenoic acid (DHA) (Best source of EPA and DHA is fish oil.) Essential fatty acid deficiency (including fats into your diet can prevent these) A. May result from following a fat-free diet B. Linked to health problems including: >Hair loss >Infertility >Low blood platelet levels >Impaired vision >Compromised brain function >Growth retardation in children

Define LDL cholesterol and HDL Cholesterol and health effects associated with each.

1. LDL: Low density lipoproteins a. Transport cholesterol from the liver to the tissues. b. Elevated LDLs promote atherosclerosis. c. Cause buildup of fatty plaque in blood vessels. 2. HDL: High density lipoproteins a. Return cholesterol from the cells to the liver for excretion. b. Slow or prevent the progression of atherosclerosis and lower cardiovascular risk.

What is hydrogenation?

A. The process of converting unsaturated fats to saturated fats by adding hydrogen B. Changes unsaturated liquid oils into solid fats such as margarine or shortening

What is trans fat? Are they more harmful to heart health than saturated fats?

A. When oils are partially hydrogenated to produce more solid fats, the normal bend can change such that the two structural parts are on opposite sides of the bend. B. This form is called a trans fatty acid, meaning "opposite side." C. Trans fatty acids are found in breads, cakes, cookies, crackers, margarine, and frozen potato products. D. Trans fatty acids decrease high-density lipoprotein (HDL). cholesterol levels and increase low-density lipoprotein (LDL) cholesterol levels. E. More harmful to the heart.

State the important functions of dietary lipids

Dietary Lipids: A. Provide fuel for energy; fats yield 9 kcal/g. B. Supply essential fatty acids - must be obtained from food. C. Support absorption of the fat-soluble vitamins - fats must be present in the food mix in the small intestine to enable absorption of vitamins A,D, E, and K. D. Add to food palatability. Promote satiety - with slower gastric emptying. Three Main Classes of Dietary Lipids: 1. Triglycerides - the chief form of fat in foods and body fat; made up of three units known as fatty acids and a backbone unit of glycerol. 2. Phospholipids - similar to triglycerides, but has a phosphorus-containing acid in place of one of the fatty acids. Phospholipids are present in all cell membranes. 3. Sterols - lipids that have a structure similar to that of cholesterol.

What is the function of triglycerides?

Store unused calories and provides the body with energy.

Differentiate between a fatty acid and a triglyceride.

lipids containing saturated fatty acids are solids at room temperature, whereas lipids containing unsaturated fatty acids are liquids. A triacylglycerol, or triglyceride, is formed when three fatty acids are chemically linked to a glycerol molecule