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Lipids, Three types?
Diverse class of molecules that are insoluble in water
- 2) Phospholipids
- 3) Sterols
Three fatty acid molecules, one glycerol molecule.
- - long chains of carbon atoms surrounded by hydrogen atoms
- - Lengths: short (<6), medium (6-12), long (>13)
- - Level of saturation: amount of hydrogen surrounding the carbon
a three-carbon alcohol that is the backbone of a triglyceride
Saturated, Monounsaturated, and Polyunsaturated fatty acids
- 1) Saturated: hydrogen atoms surrounding every carbon; no double bond
- 2) Monounsaturated: lack hydrogen atoms in one region; have one double bond
- 3) Polyunsaturated: lack hydrogen atoms in multiple locations; have 2+ double bonds
Triglycerides: long chains and bent chains
- - Long-chain: stack well together to a solid form at room temperature.
- - Bent-chain: do not stack well, and therefore are liquids at room temperature.
- The addition of hydrogen atoms to unsaturated fatty acids.
- - converts liquid fats into semisolid; margarine from plant oil
- - often creates trans fatty acids
Essential fatty acids
1) Linoleic: omega-6 fatty acid; vegetables and nut oils; blood clotting and blood pressure
2) Alpha-linolenic acid: omega-3 fatty acid; vegetables, fish, fish oils; inflammation, blood clotting, blood pressure
- - Glycerol backbone, two fatty acids, phosphate
- - soluble in water
- - Made in our bodies
- - Important components of cell membrane
- Lipids containing multiple rings of carbon atoms
- - essential components of cell membranes
- - Made in our bodies
- - Cholesterol is major sterol in body
Fat is essential to many body functions, such as...
- - Cell membrane structure
- - Nerve cell transmissions
- - Protection of internal organs
- - Insulation to retain body heat
Role of Fats
- - Provides flavor and texture to foods
- - Make us feel satiated
- - Not digested and absorbed easily because it's insoluble
Digestion of Fats
- - Mouth-> Lingual lipase digests some triglycerides
- - Stomach-> Mixed, broken into droplets
- - Gallbadder-> Contracts due to secretion of CCK and secretin from the duodenal mucosal cells; releases bile into small intestine
- - Small intestine-> Lipid-digesting enzymes from pancreas convert triglycerides into monoglycerides; also convert dietary cholesterol and phospholipids into their components; Micelles transport lipid digestion products to the enterocytes of the small intestine for absorption
- - Intestinal mucosal cell-> fatty acids reattached to monoglycerides to re-form triglycerides; protein added to form chylomicron
a lipoprotein produced by cells lining the small intestines
How much fat should we eat?
- According to AMDR, 20-35% of calories
- Athletes/highly active people can reduce to 20-25% of calories
- - Saturated fat: 7%
- - Trans fatty acids: absolute minimum
Visible fats and Hidden fats
Visible: those we can see in foods (dressing, chicken skin)
Hidden: added to processed or prepared foods to improve texture or taste
- - Dysfunction of the heart or blood vessels
- - Can result in heart attack or stroke
Three most common forms of CVD
- 1) Coronary heart disease
- 2) Stroke
- 3) Hypertension
- - Artery walls build up lipid deposits and scar tissue, blocking blood flow
- - stiffness is "hardening of the arteries"
- - Heart must work harder to push blood through vessels
Risk factors for CVD
- - Being overweight
- - Physical inactivity
- - Smoking
- - High BP
- - Diabetes
- - High blood cholesterol