Chapter 6 Lipids
cholesterol
most well known sterol essential to health found in foods derived from animals (egg yolk, liver, meat, poultry, dairy products made from cream or whole milk are rich sources of the lipid)
embolus
- thrombus or part of plaque that breaks free and travels through blood stream - lodges in artery can create same serious consequences as stationary thrombus
The Dietary Guidelines for Americans (Acceptable Macronutrient Range - AMDR) recommends that adults should keep daily fat intake
between 20 and 35% of total calories
CVD
cardiovascular disease - heart disease, stroke, disease of blood vessels - 28% of deaths
Although considered the "silent disease," hypertension can increase the risk of ______.
heart failure stroke kidney disease
healthy arteries
smooth lining
lymphatic system
transports chylomicrons to thoracic duct where they enter bloodstream though left subclavian vein in chest
plant sterols and stanols
- structurally similar to cholesterol - lipids occur naturally in small amounts in grains fruits vegetables nuts seeds and legumes - compete with cholesterol for intestinal absorption - reduces amount of cholesterol absorbed - good to combats elevated blood cholesterol levels
thrombus
- when blood clots forms too easily - fixed bunch of clots that remain in place and disrupt blood flow - partially closes of artery's lumen
essential fatty acid
- linoleic acid and alpha-linolenic acid - body cannot synthesize these two essential fatty acids
which is easier to digest lipids or carbs
carbs because they are water soluble
omega-3 fatty acid
- PUFA (omega fat) - contains first c-c double bond at third carbon from omega end of the molecule
AI for alpha-linolenic acid
1.6 g/day for men and 1.1 g/day for women
AI for linolenic acid
17 g/day for men and 12 g/day for women
Which of the following tests should a doctor perform to determine a person's risk for developing atherosclerosis?
Check blood pressure Request lipoprotein profile Test triglyceride levels
lacteals
Chylomicrons are too large to be absorbed directly into the bloodstream and must pass through the larger openings of lacteals, which are lymphatic system vessels in each villus.
gallstones
Small crystals that form from bile in the gallbladder - main component is cholesterol
how are fatty acids transported through the bloodstream
as part of lipoproteins
what foods supply good sources of linoleic acid
pecans, almonds, avocado
bile salts
compounds in bile that aid in emulsification in the small intestine
CLA
conjugated linoleic acid
Compared to foods made with unprocessed plant oils, partially hydrogenated oils are less likely to go rancid because
contain fewer double bonds
tropical oils
contain more saturated than unsaturated fatty acids
fatty acids and cis fatty acids
most naturally occurring unsaturated fatty acids
fat malabsorption
poor absorption of fat soluble vitamins
steatorrhea
presence of lipid in stool - to prevent this and maximize fat absorption individual with missing or damaged gallbladder should eat smaller more frequent meals - avoid high fat meals
small intestine
primary site of lipid digestion and absorption
liver
produces bile
chylomicron
specific type of lipoprotein formed in enterocytes - transports the most triglycerides
gallbladder
stores bile
lipoproteins
water-soluble structures that transport lipids through the bloodstream
choline
water-soluble, vitamin-like compound; component of lecithin
sources of trans fat conjugated linoleic acid (CLA)
whole milk, butter, meat form grass-fed cows
high risk individuals of gallstones
women, over age 40, family history of gallstones, overweight, obese, those who lose weigh rapidly. American Indians and Mexican-Americans
low-density lipoprotein (LDL)
- VLDL becomes LDL - transports cholesterol and other lipids to tissues - cells remove LDL from bloodstream and use its lipids to make vital substances and structures - transports most cholesterol
what foods supply good sources of alpha linoleic acid
fatty fish, salmon, tuna
lipid storage diseases
genetic conditions that cause lipid accumulation in cells which damages tissues
end products of lipid digestion
glycerol, fatty acids, monoglycerides, cholesterol, and phospholipid fragments - later reassembled
pancrease
secretes lipase into small intestine to aid in digestion of fat
enterohepatic circulation
the process of recycling bile from the large intestine back to the liver to be reused during fat digestion 1. liver makes bile from cholesterol 2. stores bile until needed, then secretes bile into small intestine 3. duodenum receives bile from gallbladder, bile facilitates lipid digestion 4.ileum absorbs bile salts from bile, soluble fiber reduces absorption of bile salts 5. hepatic portal vein, bile salts return to liver bile salts absorbed in ileum of small intestine, bile salt travels through blood to liver, liver recycles used bile salts to make new bile - to reduce this soluble fiber
functions of lipids
- absorb fat soluble vitamins and phytochemicals - cushion body against bumps and blows - form/maintain cell membranes - participate in cell signaling - insulation - produce steroid hormones - provide and store energy (triglycerides) - enhance flavor, texture, and aroma of food
List the steps of dietary fat absorption from absorption in the small intestine and ending with entrance into the lymphatic system.
- absorption of glycerol, monoglycerides, and fatty acids into small intestinal cells - triglycerides are reassembled - triglycerides are packed into chylomicrons - chylomicrons enter lymphatic system
source of SFAs
- animal foods contain higher percentages of SFAs than most plant foods
gangrene
- artery to limb blocked tissue in extremity die
hypertension
- atheroscleosis contributes to hypertension - chronic condiiton - highe blood pressure even when person is relaxed - major risk factor in developing atherosclerosis and heart disease - work harder to circular blood through abnormally stiff arteries - elevated blood pressure can cause hardened arteries to tear/burst
lipases
- break down triglycerides and phospholipids - fat digesting enzymes because they can be absorbed
oxidation
- chemical process that alters compound's structure - saturated/trans fatty acids tend to go rancid because they are less likely to oxidizi
steps of atherosclerosis
- damage occurs in blood vessel lining - plaque deposited - plaque accumulates - pressure in artery increased - clot or spam in plaque clogged artery leads to heart attack
rich sources of lecithin
- egg yolks liver wheat germ peanut butter and soybeans - most abundant phospholipid in food - contains choline
source of MUFAs
- olive oil
high-density lipoprotein (HDL)
transports least triglycerides carries the most protein
functions of phospholipids in the body
needed for normal functioning of nerve cells aid in fat digestion and absorption form lipid bilayer of cell membranes
myocardial infraction
- heart attack - brain cells that are nourished by vessel die
fatty acids
- hydrocarbon chain - one end of the fatty acid has methyl group - other end is carboxylic acid
arterial plaques
- interferes with circulation because it narrows artery and block opening (lumen) - cause clots to form by roughening the smooth arterial surface and slowing blood flow. rupturing plaque causing a clot formation to repair rupture.
passages of fats in digestive system
- lipase in saliva mixes with food - food enters stomach - acidic stomach activates lipase - small intestine major site of digestion - fatty chime leaves stomach and enters small intestine simulates hormone secretion of CCK and secretin - secretin stimulates liver to produce bile and pancreas to secrete pancreatic juice to neutralize stomach acid - CCK signals pancreas to secrete digestive enzymes (pancreatic lipase) - CCK triggers gallbladder to release stores bile and sphincter that controls flow of bile and pancreatic juice and duodenum to opn
sources of polyunsaturated fats
corn oil and soybean oil
To meet the Dietary Guidelines for Americans recommendation for fat intake, an individual should ______.
emphasize foods such as fish, nuts, and vegetable oils balance intake of low-fat and high-fat foods
lipoprotein lipase
enzyme in walls of capillaries breaks down triglycerides in the chylomicron into fatty acids and glycerol
lipid digestion in small intestine
fatty chyme stimulates release of CCK, CCK signals pancreas to secrete digestive enzymes including pancreatic lipase, into duodenum, pancreatic lipase digests triglycerides and converts them into monoglycerides and 2 fatty acid molecules
According to the Dietary Guidelines, cholesterol intake should be ______.
limited
fat digestion occurs when
lipase breaks triglycerides down to monoglycerides bile from the gallbladder is present
production of bile via liver and storage of bile via gallbladder aids in what
lipid digestion by emulsifying lipids
triglyceride
lipid that has three fatty acids attached to three-carbon compound called glycerol
pancreatic phospholipase
removes fatty acid from second position of phospholipid molecule
pancreatic lipase
removes two fatty acids from each triglyceride molecule
The most common forms of cardiovascular disease in the US include ______.
stroke, heart disease
emulsifier
substance that keeps water-soluble and water-insoluble compounds mixed together
atherosclerosis
- lipid hardening - most cases of heart disease and stroke result from this - chronic process that affect artery function - caused by decreased aterial blood flow and arteriosclerosis - long-term disease process in which plaques build up inside the arterial walls - is a condition that can inhibit the blood flow and permanently damage the kidneys, eyes, legs, heart, and brain.
sterols
- lipid that have more chemically complex structure than triglyceride and phospholipid
triglycerides in foods
- mixture of unsaturated/saturated fatty acids - olive and cheeses - type of fatty acid (SFA, MUFA, and PUFA) often predominates
partial hydrogenation
- most of trans fat in processed food resulted from this - food manufacturing process that adds H atoms to some unsaturated fatty acids in liquid vegetable oil - converts cis to trans fatty acids - decrease rancidity (unappetizing odor and taste) - increase shelf life of a product - convert liquid oils to more solid fats
The major adverse health conditions associated with consuming high amounts of fat are _____.
- obesity - stroke - heart disease - certain cancers
PHOs
- partially hydrogenated oils - oils that contain these artificial fats - foods mad with PHOs can be stored for longer periods than foods that contain cis fatty acids because they have fewer double bonds
how does an emulsifier work?
- prevents fat from coalescing by using shell of water molecules - isolates individual fat droplets
arteriosclerosis
- reduced arterial wall flexibility - hardening of arteries - results from injury - ART IS SYMPTOM OF ATH - a loss of arterial flexibility or "hardening of the arteries"
classification of fatty acids
- saturated fatty acid - unsaturated fatty acid
classes of lipids
- triglycerides - phospholipids - sterols (ex. cholesterol)
ghee
- type of clarified butter - alternative to cooking oil - does not contain water or milk proteins - solid at room temp - higher smoke point
According to the Dietary Guidelines to reduce risk for cardiovascular disease, saturated fats should contribute
no more than 10% of total kilocalories.