Lesson 5: Lipids Flashcards
What are the 4 types of lipids?
Fatty Acids
Triglycerides
Phospholipids
Cholesterol
Why are lipids necessary?
Enhance flavor
Increase intestinal absorption of fat-soluble vitamins and phytochemicals
Contribute to satiety
Which fat protects the abdominal organs?
Visceral fat
Which fat helps maintain body heat and cushions the body?
Subcutaneous fat
Which fat increases the chances of cardiovascular disease?
Visceral fat
True or False: Fat provides more than twice the energy of carbs and protein
True
True or false: Lipids are the main source of energy when we are at rest
True
Do we store energy mostly as fat or glycogen?
Fat
What is the downside of energy storage as fat?
We can store an unlimited amount
Which lipid is the basic building block of most lipids and is composed of a chain of carbon atoms attached to hydrogen atoms?
Fatty acids
Which lipid is made up of 3 fatty acids?
Triglycerides
Which lipid is made up of 2 fatty acids?
Phospholipid
Which lipid contains no fatty acids and is not used as a source of energy?
Cholesterol
What does each fatty acid contain?
a methyl group at one end
Acid group at another end
Length of short chain FA
2-4 carbons long
Length of medium chain FA
6-12 carbons long
Length of long chain FA
14-24 carbons long
Do saturated fatty acids contain double bonds?
No
Do unsaturated fatty acids contain double bonds?
Yes
What does the double bond cause?
A kink in the chain
What do we called an FA with one double bond within carbon chain?
monounsaturated fatty acid
What do we called an FA with two or more double bonds within carbon chain?
polyunsaturated fatty acid
What determines the shape of a fatty acid?
Saturation
What does saturation also determine?
Behavior of the lipid
Are saturated FAs liquid or solid at room temperature?
Solid (ex: butter)
Are unsaturated FAs liquid or solid at room temperature?
Liquid (ex: oil)
Are omega 3 and 6 essential nutrients?
Yes our body cannot synthesize them so they need to be supplied by the diet.
What kind of fatty acid is linoleic acid?
Omega 6
What kind of fatty acid is linolenic acid?
Omega 3
What are the two other omega 3 fatty acids that can be synthesized from linolenic acid?
DHA (docosahexaenoic acid)
EPA (eicosapentaenoic acid)
In what foods are DHA and EPA rich in?
Fish oils and shellfish
Which omega 3 is essential for the development of the brain and improves learning?
DHA
Which omega 3 lowers blood pressure, reduces clot formation and reduces inflammation?
EPA
What two shapes can unsaturated fatty acids come in?
Cis fatty acid
Trans fatty acid
What is a cis fatty acid?
If H atoms next to a double bond are on the same side of the chain
What is a trans fatty acid?
If H atoms are on opposite sides of the chain
Through what process do unsaturated FAs go from cis-shape to trans-shape?
Hydrogenation
Products made with _________ have a longer shelf life.
Trans fats
Which is the most common lipid found in our food?
Triglycerides
What are triglycerides composed of?
3 fatty acids + 1 glycerol molecule
True or False: FA of triglycerides can be either monounsaturated or polyunsaturated?
False. They can also be saturated
What happens to oils with high amounts of PUFA when deep fried?
Turn rancid
Under prolonged exposure to high heat, what happens to the double bonds in the fatty acid?
they break
What is a free radical?
atom with incomplete valence shell
Why are PUFAs more sensitive to becoming free radicals?
Due to multiple double bonds in the cis-configuration
Why are saturated and monounsaturated fatty acids more heat stable?
They have one or fewer double bonds
What is a diglyceride with a polar end attached to two non-polar hydrocarbon tails?
Phospholipid
Which is the most common phospholipid?
Lecithin
What are the roles of phospholipids?
Major structural component since they make up cell membranes of all living organisms
What do we call the two sheets of phospholipids that make up the cell membrane?
The lipid bilayer
Phospholipids contain a _____________ head and __________ tail.
Hydrophilic head
Hydrophobic tail
Which omega 6 fatty acid is present in the phospholipid bilayer?
Arachidonic acid
What do we call a substance with both water-soluble and fat-soluble portions that promotes the mixing of oils and fats in a watery solution?
Emulsifiers
Where is cholesterol found?
Only in the animal kingdom…not found in plants
Is cholesterol an essential nutrient?
No, the liver can synthesize it
Does cholesterol contain fatty acids? Is it broken down for energy?
No and no
What are the roles of cholesterol in the body?
Synthesis of estrogen and testosterone
Role in vitamin D synthesis
Bile contains cholesterol and is crucial to the digestion of lipids
What does it mean to be hydrophobic?
water-fearing or non-water soluble
What does it mean to be hydrophilic?
water-loving or water-soluble substances
Where does the bulk of chemical digestion of lipids occur?
In the small intestine
Which accessory organs aid in chemical digestion of lipids?
Liver
Gallbladder
Pancreas
What does bile contain?
Cholesterol, salts and lecithin
What hormone is triggered when fat enters the small intestine?
cholecystokinin (CCK)
What does CCK do?
Signals the gallbladder to release it’s store of bile
What does the excretion of bile help do?
Reduce blood cholesterol
Small molecules of digested triglycerides can diffuse easily into intestinal cells so they are absorbed directly into the bloodstream. What about larger molecules?
They merge into spherical complexes called micelles
What are micelles?
Emulsified fat droplets formed by molecules by bile surrounding monoglycerides and fatty acids
Once long chain FAs cross into epithelial cells they get repackaged into _________.
chylomicrons
What is a chylomicron?
lipoprotein that is too large to enter into blood vessels, so it inters the lacteal vessel which delivers it to the left subclavian vein
What are the 4 types of lipoproteins?
Chylomicrons
LDLs
VLDLs
HDLs
What do chylomicrons do?
Transport dietary triglycerides and transport them to fat cells and muscle cells before returning them to the liver.
What are VLDLs?
A product of the liver that contain mostly triglycerides
What happens to VLDLs as they travel through the body?
The body cells remove triglycerides, causing the VLDLs to shrink. Since it has lost triglycerides, the proportion of lipids shift and cholesterol becomes the predominant lipid & lipoprotein density increases. So, they are cholesterol rich remnants called LDLs.
What are LDLs?
Low density lipoproteins composed of cholesterol. They deliver cholesterol to cells but are considered the “bad” cholesterol.
What are HDLs?
High density lipoproteins synthesized in the liver. They are mostly protein and considered good cholesterol.
What do HDLs do?
They scavenge for cholesterol from dead cells and return to the liver.
What is enterohepatic circulation?
The fact that most of the bile released into the small intestine is reabsorbed and sent back to the liver to be reused. Some is also excreted.
Which blood cholesterol is linked to heart disease and increased risk of heart attack?
LDL
Which blood cholesterol has a protective affect?
HDL
What do the following factors do: Weight control Unsaturated fat in the diet Soluble dietary fibers Phytochemicals Moderate alcohol consumption Physical activity
lower LDL/raise HDL
What does the path leading to CVD begin with?
inflammation of the arterial wall
What is a consequence of the immune response (inflammation) to CVD?
Plaque deposits. Arteries harden and narrow
Blood vessels narrow & can become blocked
What do we call the death of cardiac muscle tissue resulting from blockage of one or more coronary arteries?
Heart attack
What do we call partial blockage of the coronary arteries that results in chest pains?
Angina pectoris
What is the death of nervous tissue in brain, usually resulting from rupture or blockage of arteries in head?
Stroke
How can we reduce the risk of CVD?
Increase soluble fiber intake
Limit your fat intake to the AMDR
Increase your risk of omega 3 intake (anti inflammatory effect on body)
If lifestyle changes dont work, can use medications like Statin to interfere with liver’s ability to make cholesterol
What is the AI of omega 3 for women?
1.1 grams/day
What is the AI of omega 3 for men?
1.6 grams/day
