Chapter 5 - Lipids Flashcards
What is the AMDR recommendation for fat?
20-35% of energy consumed
What are lipids?
- a group of organic molecules, most of which don’t dissolve in water
- contribute to texture, flavour, aroma of food
- incl. fatty acids, triglycerides, phospholipids, sterols
What is “good” cholesterol? What is “bad” cholesterol?
"good" = high density lipoproteins (HDL) cholesterol "bad" = low density lipoproteins (LDL) cholesterol
What kind of an impact does soluble fibre have on LDL cholesterol?
fibre lowers LDL b/c it binds to it
What are triglycerides?
The major form of lipid in food & in the body
- consist of 3 fatty acids attached to a glycerol molecule
- these fatty acids determine the physical properties & health effects of the triglycerides we consume
What are fatty acids?
organic molecules made up of a chain of carbons linked to hydrogen atoms w. an acid group at one end
What are phospholipids?
type of lipid containing phosphorous
ex. phosphoglyceride
What are sterols?
types of lipids w. a structure composed of multiple chemical rings
What is a saturated fatty acid?
a fatty acid in which the carbon atoms are bound to as many hydrogens as possible, and which, therefore, contains no carbon-carbon double bonds
- associated w. increased risk of cardiovascular disease
What are monounsaturated fatty acids?
contains 1 carbon-carbon double bond (i.e. some carbons that are not saturated w. hydrogens)
- ex. oleic acid (i.e. olive oil, canola oil)
What are polyunsaturated fatty acids?
contains 2+ carbon-carbon double bonds
- ex. linoleic acid (i.e. corn oil, safflower oil, soybean oils)
What are omega-3 fatty acids?
contains a carbon-carbon double bond b/w the 3rd & 4th carbons from the omega end
- ex. alpha-linolenic acid, EPA, DHA
What are omega-6 fatty acids?
contains a carbon-carbon double bond b/w the 6th & 7th carbons from the omega end
- ex. linoleic acid (safflower, corn oils), arachidonic acid (meat & fish)
What is the ‘cis’ configuration of fatty acids?
when both hydrogen atoms are on the same side of the double bond
- most unsaturated fats
What is the ‘trans’ fatty acid configuration?
when the hydrogen atoms are on opposite sides of the double bond
- trans fats
What is hydrogenation?
the process whereby atoms are added to the carbon-carbon double bonds of unsaturated fatty acids, making them more saturated
- most trans fats come from this process
What are phosphoglycerides?
a class of phospholipids consisting of a glycerol molecule, 2 fatty acids, and a phosphate group - soluble in both water & fat --> important for many functions in the body
What are emulsifiers?
substances that allow water & fat to mix by breaking large fat globules into smaller ones
- ex. egg yolks in cake batter
- an important component of cell membranes in the body
What is a lipid bilayer?
2 layers of phosphoglyceride molecules oriented so that the fat-soluble fatty acid tails are sandwiched b/w the water-soluble phosphate-containing heads
- forms the barrier of a cell that helps regulate which substances can pass into and out of the cell
What is lecithin?
a phosphoglyceride composed of a glycerol backbone, 2 fatty acids, a phosphate group, and a molecule of choline
- req’d for optimal function of cell membranes, memory
- found in eggs & soybeans
What is cholesterol?
a lipid that consists of multiple chemical rings and is made only by animal cells
- a sterol
- necessary in the body, but not in the diet b/c liver manufactures it
What can plant sterols do?
- reduce cholesterol levels in the body by decreasing cholesterol absorption from the diet
What are lipases?
lipid-digesting enzymes
- digestion of dietary fat in small intestine
What are micelles?
particles formed in the small intestine when the products of fat digestion are surrounded by bile acids
- facilitate the absorption of fat
What are lipoproteins?
- transport lipids in the blood
What is the post-prandial state?
the time following a meal when nutrients from the meal are being absorbed
What are chylomicrons?
lipoproteins that transport lipids from the mucosal cells of the small intestine and deliver triglycerides to other body cells
What is lipoprotein lipase?
an enzyme that breaks down triglycerides into fatty acids and glycerol as chylomicrons circulate in the blood
- attached to the cell membranes that line the blood vessels
What are VLDLs?
very-low-density lipoproteins
- assembled by the liver; carry lipids from the liver & deliver triglycerides to body cells
What are LDLs?
low-density lipoproteins
- transport cholesterol to cells
- elevated LDL cholesterol increases risk of cardiovascular disease
What is an LDL receptor?
a protein on the surface of cells that binds to LDL particles and allows their contents to be taken up for use by the cell
What are HDLs?
high-density lipoproteins
- pick up cholesterol from cells and transport it to the liver so that it can be eliminated from the body (reverse cholesterol transport)
- high level of HDL decreases risk of cardiovascular disease
- “good” cholesterol
What is adipose tissue?
tissue found under the skin and around body organs that is composed of fat-storing cells
- most of the lipids in the human body are triglycerides stored in this tissue
- also insulates the body from changes in temp & provides a cushion to protect internal organs against shock
What are essential fatty acids?
fatty acids that must be consumed in the diet b/c they cannot be made by the body or cannot be made in sufficient quantities to meet needs
- ex. omega-3 fatty acids, omega-6 fatty acids
- essential to the formation of the phospholipids that give cell membranes their structure & functional properties
What are eicosanoids?
regulatory molecules (incl. prostaglandins & related compounds) that can be synthesized from omega-3 and omega-6 fatty acids - help regulate blood clotting, blood pressure, immune function, other body processes
What is beta-oxidation?
- 1st step in the production of ATP from fatty acids
- breaks the carbon chain of fatty acids into 2-carbon units that form acetyl-CoA & releases high-energy electrons that are passed to the electron transport chain
What is hormone-sensitive lipase?
an enzyme present in adipose cells that responds to chemical signals by breaking down triglycerides into free fatty acids & glycerol for release into the bloodstream
- when less energy is consumed than is needed
What is the glucose/fatty-acid-cycle?
the inverse relationship b/w blood glucose & free fatty acids
- when blood glucose levels are high, as in the post-prandial state, free-fatty-acid levels are low
- in the fasting state when blood glucose levels decline, free-fatty-acid levels increase
What is essential fatty acid deficiency?
a condition characterized by dry scaly skin & poor growth that results when the diet does not supply sufficient amounts of the essential fatty acids
- rare
What is atherosclerosis?
- a type of cardiovascular disease
- build up of fatty material in the artery walls, reducing their elasticity and eventually blocking blood flow
What is atherosclerotic plaque?
cholesterol-rich material that is deposited in the arteries of individuals with atherosclerosis
- consists of cholesterol, smooth-muscle cells, fibrous tissue & eventually calcium
What is oxidized LDL cholesterol?
- formed when cholesterol in LDL is oxidized by reactive oxygen molecules
- key in the development of atherosclerosis b/c it contributes to the inflammatory process
