Chapter 6 - Lipids Flashcards
What are the 3 types of fats?
Triglycerides, phospholipids, and sterols
What are the 3 fats composed of?
Carbon, Hydrogen, and Oxygen
Do the fats dissolve in water?
No, they dissolve in organic solvents
Triglyceride
Most common form of lipid in the body and in food; composed of 3 fatty acids bonded to the alcohol glycerol
Esterification
Process of attaching fatty acids to a glycerol molecule, creating an ester bond and releasing water.
Removing a fatty acid is called de-esterifcation and reattaching a fatty acid is re-esterification
Ester
Organic compound that has an O•C group attached to a carbonyl group; product of a reaction between a carboxylic acid and an alcohol; the formation of triglycerides involves forming ester bonds.
Free Fatty Acids
Fatty acid that isn’t attached to a glycerol molecule
Diglyceride
Breakdown product of a triglyceride; consists of 2 fatty acids bonded to a glycerol backbone
Long Chain Fatty Acid
Fatty acid containing 12 or more carbons.
This fatty acid takes the longest to digest and is transported via the lymphatic system
Where are long chain fatty acids found?
In fats from beef, pork, and lamb; most plant oils
Medium Chain Fatty Acid
Fatty acid with 6 to 10 carbons.
Digested rapidly, like glucose; transported via circulatory system.
Where are medium chain fatty acids found?
In coconut and palm kernel oils
Short Chain Fatty Acid
Fatty acid with less than 6 carbons
Digests rapidly; transported via circulatory system
Where are short chain fatty acids found?
In dairy products (butter, whole milk)
Saturated Fattty Acid (SFA)
Fatty acid with no carbon-carbon double bonds
Monounsaturated Fatty Acid (MUFA)
Fatty acid with one carbon-carbon double bond
Polyunsaturated Fatty Acid (PUFA)
Fatty acid with two or more carbon-carbon double bonds
What is the maximum number of bonds a carbon atom can form?
4
What is the maximum number of bonds an oxygen atom can form?
2
What is the maximum number of bonds a hydrogen atom can form?
1
Fatty Acid
Chain of carbons chemically bonded together and surrounded by hydrogen molecules. These hydrocarbons are found in lipids and contain a caarboxyl (acid) group and a methyl group.
Hydrogenation
Addition of hydrogen to some carbon-carbon double bounds, producing some trans fatty acids. This process is used to convert liquid oils into more solid fats.
Both ways of naming fatty acids are based on what?
The number of carbons and double bond locations
Omega (w or n) Naming System
Indicates where the first double bond closest to the methyl (omega) end of the chain occurs
Delta (▲) Naming System
Described fatty acids in relation to the carboxyl end of the carbon chain and indicates the location of all double bonds
Essential Fatty Acids (EFAs)
Fatty acids that must be supplied by the diet to maintain health.
Currently, only linoleic acid and alpha-linoleic acid are classified as EFAs.
Where does the double bond occur on omega-3?
after the 3rd carbon from the methyl end
Where does the double bond occur on omega-6?
after the 6th carbon from the methyl end
Eicosanoids
Hormone-like compounds synthesized from polyunsaturated fatty acids, such as omega-3s and omega-6s
Prostaglandins
Potent eicosanoid compounds that produce diverse effects in the body
What are some fat replacements?
Protein (Dairy Lo) Starch derivatives (Z-Trim) Fiber (Maltrim, Stellar, Oatrim) Engineered Fats Water
Why are fat replacements rarely used?
Not very versatile or practical
What is the role of triglycerides?
concentrated source of energy
insulates and cushions vital organs
helps transport essential nutrients in blood stream
What is the main fuel course for all body cells except the nervous system and red blood cells?
Triglycerides
When you’re resting or doing light physical activity, what percentage of energy burnt is triglycerides?
30-70%
What is the main storage form of energy?
Triglycerides
The fat cell is __% lipid and __% water and portein
80% ; 20%
Visceral Fat
Fat that cushions organs, preventing jostling, injury
What 3 things are important for cell wall structure by keeping the cell wall fluid and flexible?
EFAs, phospholipids, and cholesterol
What are 5 roles of the eicosanoid?
- Regulates cell division rates
- Maintain normal kidney function and fluid balance
- Direct hormones to their target cells
- Regulate flow of substances into and out of cells
- Regulate ovulation, body temperature, immune system function, and hormone synthesis
Phospholipids have the ________ compound, which allows fat to function in a watery environment without clumping together
phosphate
What are the two major roles of phospholipids?
cell membrane component, emulsifier
Emulsifier
Compound that can suspend fat in water by isolating individual fat droplets using a shell of water molecules or other substances to prevent the fat from coalescing
What are the two main emulsifiers?
Bile and lecithin
What is essential to digest fat and transport it through the blood stream?
emulsifiers
Phospholipids are used in foods as…
emulsifiers in food preparation and manufacturing
Phospholipids are found in what?
Egg yolks, wheat germ, peanuts
What do sterols do?
Synthesize many compounds
Cholesterol
- Forms cell membranes
- Allows fat soluble substances in/out of cell
- Forms shell covering chylomicrons (droplets that transport liquids)
- Make bile to emulsify fats
The body absorbs how much consumed cholesterol?
40-60%
Where is cholesterol found?
in foods of animal origin; however, 2/3 of our body’s cholesterol is synthesized by our bodies
What sterols do plants make?
ergosterol (a form of vitamin D) and sitostanol (added to margarines)
What is the RDA for fat?
There is no RDA for fat.
What is the AMDR for total fat?
20-35% of calories
You should consume more of this fat than any other kind of fat.
Unsaturated
Mediterranean Diet
Most fats in this diet are monounsaturated fats.
This diet lowers rate of chronic diseases and is heart healthy.
What is the AI for EFAs?
120 cal for women, 170 cal for men
EFA deficiency leads to..
diarrhea, slowed growth, delayed healing of wounds and infections, and flaky, itchy skin
What is the AI for linoleic acid?
14-17g/day for men, 11-12g/day for women
What is the AI for alpha-linoleic acid?
1.6g/day for men, 1.1g/day for women
Role of the mouth in fat digestion and absorption?
Lingual lipase is secreted.
Little to no fat is digested.
Role of the stomach in fat digestion and absorption?
Gastric lipase is secreted.
Little fat is digested.
Role of the liver in fat digestion and absorption?
The liver produces bile, which is stored and released by the gallbladder into the common bile duct, which empties into the small intestine.
Bile emulsifies fat.
Role of the pancreas in fat digestion and absorption?
Secretes pancreatic lipase, phospholipace, and cholesterol esterase into the common bile duct, which empties into the small intestine.
Pancreatic lipase digests triglycerides.
Phospholipase digests phospholipids.
Cholesterol esterase digests cholesterol.
Role of the small intestine in fat digestion and absorption?
MOST DIGESTION OCCURS HERE
Fat is digested and abosorbed in the duodenum and jejunum.
Bile is reabsorbed in the ileum.
Role of the large intestine in fat digestion and absorption?
Less than 5% of fat passes through and is excreted.
Micelle
Water-solublem spherical structure formed by lecithin and bile acids in which the hydrophobic parts face inward and the hydrophilic parts face outward.
What percent of dietary fat is absorbed/
95%
What percent of bile is recycled?
98%, the rest is excrete in the feces
Lipoprotein
Compound containing a core of lipids with a shell composed of protein, phospholipid, and cholesterol.
Shell lets it circulate in the blood.
Chylomicron
Lipoprotein made of dietary fats surrounded by a shell of cholesterol, phospholipids, and protein.
Apolipoprotein
Protein attached to the surface of alipoprotein or embedded in its outer shell.
What does an apolipoprotein do?
- turn on a lipid transfer enzyme
- assist in binding a lipoprotein to a receptor on a cell surface
- assist enzymes
Chylomicrons and secreted by what?
Lacteals in the intestinal villi
Antioxidant
Compound that protects other compounds, such as unsaturated fats, and body tissues from the damaging effects of oxygen.
anti = against
oxidant = oxygen
Very-Low-Density Lipoprotein (VLDL)
Lipoprotein, created in the liver, that carries both cholesterol and lipids taken up from the blood stream by the liver and those are are newly synthesized by the liver.
Intermediate-Density Lipoprotein (IDL)
Lipoprotein formed as triglyceries are released and make VLDLs more dense.
Low-Density Lipoprotein (LDL)
Lipoprotein in the blood containing primarily cholesterol; elevated LDL cholesterol is strongly linked to cardiovascular diease (CVD) risk
Receptor Pathway for Cholesterol Uptake
Process by which LDL is bound by cell receptors and incorporated into the cell.
Uses LDL receptor B-100.
Scavenger Pathway for Cholesterol Uptake
Process by which LDL is taken up by scavenger cells embedded in the blood vessels. Basically, oxidized LDL is engulfed and digested.
Over time, cholesterol-filled scavenger cells build up on the inner blood vessel walls, especially the arteries, developing what?
Plaque
Atherosclerosis
Build up of fatty material (plaque) in the arteries, including those surrounding the heart
High-Density Lipoprotein (HDL)
Lipoprotein that picks up cholesterol from cells and transfers it in the blood stream to the liver. A low blood HDL value increases the risk of cardiovascular disease.
“Good” cholesterol
Homocysteine
Amino acid no used in protein synthesis but, instead, produced during metabolism of the amino acid methionine.
Homocysteine is likely toxic to many cells, such as those lining the blood vessels.
CVD Risk Factors
- High fat diet
- Age (65)
- Gender (male)
- Genetics
- Race (African)
- High LDL and total blood cholesterol levels
- High blood triglyceride levels (hypertriglyceridemia)
- Hypertension
- Smoking
- Physical inactivity
- Obesity
- Diabetes
- Liver and kidney diseases
- Low thyroid hormone levels
Rancid fats have these two compounds which can damage our cells.
Peroxides and Aldehydes
The FDA defines trans fat free as…
having less than 0.5g/serving of trans fats