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Chapter 5 lipids
Terms in this set (55)
do lipids readily dissolve in water?
types of lipids
1. triglycerides (fat)
3. sterols (cholesterol)
fats are... oils are..
how many kcal do lipids yield?
building blocks of fat; chain of carbons flanked by hydrogens
saturated fatty acids
- no double bonds within the carbon chain- saturated with hydrogen atoms
- solid form at room temperature (butter, lard- mainly animal products)
unsaturated fatty acids
contain at least one double bond
1. monounsaturated fat
2. polyunsaturated fat
one double bond (canola, peanut, and olive oils)
2 or more double bonds (corn, soybean, sunflower, and safflower oils. fish oils too)
has highest amount of unsaturated fat- however, it's a medium chain, so it is processed differently by the body
most common form of fats and oils; 3 fatty acids attached to a glycerol backbone
- built on a glycerol backbone- 2 fatty acids + a phosphate group
- cell membranes
- fat digestion
*Lecithin- main phospholipid added to food to help stabilize products such as ice cream
Are phospholipids an essential nutrient?
no; they can be produced by the body
multi-ringed compound with hydroxyl group; do NOT have a glycerol backbone; plants have sterols, but not cholesterol (animals only)
functions of cholesterol
1. cell membranes- all of our cell membranes have cholesterol; critical to cell membranes
2. sex hormones, vitamin D, and bile— cholesterol is sometimes converted to vitamin D; sex hormones are also produced by cholesterol
how is cholesterol eliminated from the body?
only by the liver
what controls blood cholesterol?
Diet, but also if you build up too much cholesterol, you want to push some into the liver- which is what cholesterol medication does
is cholesterol an essential nutrient?
no; most cholesterol is actually made by the body
what plays a huge role in how much cholesterol goes into the body?
absorption (the egg man)
cholesterol and the brain
large amount of cholesterol in the brain-- so if we lower cholesterol too much, we lower brain cholesterol... could that cause neurological issues?
fat in foods provides
fat replacement strategies
1. engineered fats
3. avoiding rancidity
artificial fats that binds fat-soluble vitamins
*Olestra: undigestible, caused abdominal cramping, and inhibited absorption of vitamins and nutrients
limits shelf life of foods; saturated fat and trans fat lasts longer than unsaturated fat
-the process used to solidify an oil by adding hydrogen (crisco, margarine)
- increases trans fatty acid content
- hydrogens are placed on opposite sides and the chain becomes straight. They're still unsaturated, but the hydrogens are flipped, causing the straight chain
negative effects of trans fats
1. increased blood cholesterol
2. increased heart disease
3. increased inflammation
4. obesity and diabetes?
enzymes that break down triglyceride molecules
digestion of fat in the stomach
*limited digestion takes place in the stomach
1. fat separates from other food components into oil droplets
2. gastric lipase breaks down lipids
where is the primary site of fat digestion?
fat digestion in small intestine
- when fat enters, the gallbladder contracts, releasing bile
- bile acts as an emulsifier
- causes the release of pancreatic lipase
- digests emulsified fat-- fat is broken down into monoglycerides and fatty acids
made up of
, cholesterol, and salts; fatty acids penetrate small intestine like thumbtacks on a styrofoam ball
absorption of fat
1. dietary fat is absorbed into intestinal cells
2. fatty acids and monoglycerides reform into triglycerides and enter into the lymphatic system
balls of fat that transport lipids throughout the body; they are produced in different sizes, and they are how we transport lipids through the bloodstream (since water in blood and oil in fat are incompatible)
-ball of emulsified fat
- made by the small intestine
Are triglycerides present in blood chylomicrons?
- breaks down blood lipoproteins
- composed of fatty acids + glycerol
what happens to chylomicrons when fat is broken down?
what happens to the shrunken chylomicrons?
They go to the liver
- very low density lipoprotein
- made by the liver
- carries mostly fat from the liver
- also broken down by lipoprotein lipase
what happens to the remaining VLDL after lipoprotein is broken down by lipoprotein lipase?
it goes into the bloodstream
- low density lipoprotein
- made by the liver
- transports mostly cholesterol to the cells
- known as "bad cholesterol"
- high density lipoprotein
- made by liver and small intestine
- known as "good cholesterol"
- transports cholesterol from body's cells to the liver for excretion
Which is the most abundant lipoprotein particle?
How can HDL reduce cholesterol in the heart?
when excess cholesterol builds up in the cells of the heart, HDL picks it up and takes it back to the liver
essential fatty acids
- must be consumed in the diet
- needed to produce important biological compounds
- 5% of kcal should come from essential fatty acids
1. omega 6
2. omega 3
- linoleic acid- increases blood clotting and increases immune response; gets converted into arachidonnic acid
- found in plant oils
-alpha-linoleic acid- decreases blood clotting, decreases inflammation; (but only clotting and inflammation associated with heart disease and stroke) gets converted to DHA and EPA
- also lowers blood lipids and helps with brain development and eyesight
- found in fish and plant oils
food sources of alpha-linoleic acid
canola oil, soybean oil, walnuts, flax seeds, shrimp, crab
food sources of DHA and EPA
fatty fish, salmon, tuna, sardines
- diet-induced heart disease- "hardening of the arteries"
- takes many years to develop
- associated with inadequate blood circulation
1. begins (as early as childhood) with accumulation of lipid in the arteries
2. build up gradually enlarges and develops into plaques (lesions) in the arteries of the heart.
3. The cholesterol is dropped into the lesions.
4. This continues until the lesions block blood flow, causing a heart attack
heart attack; when blood flow surrounding the heart is interrupted, causing irregular heartbeat or cessation of heartbeat.
list the steps of fat digestion and absorption starting at the mouth and ending at the small intestine
1. Some lipase is released by the salivary glands and stomach
2. salivary lipase and gastric lipase begin digesting short-chain fatty acids in the stomach
3. Bile emulsifies the fats
4. pancreatic lipase digests long-chain fatty acids and triglycerides
5. triglycerides are broken down and absorbed in the small intestine
place the steps of dietary fat absorption in the order they occur
1. glycerol, monoglycerides, and fatty acids are absorbed from the lumen of the small intestine into the small intestinal cells
2. triglycerides are reassembled within the cells lining the small intestine
3. triglycerides are packaged into chylomicrons
4. chylomicrons enter the lymphatic system
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