Lipids Flashcards
What are the functions of fats?
- Energy stores
- Muscle fuel
- Padding
- Insulation
- Cell membranes (major material)
- Raw materials (converted to other compounds like hormones, bile, vit D)
What is the base unit of lipids?
Fatty acids
What are fatty acids?
chain of carbons with hydrogen atoms along the chain and at one end (methyl) and carboxyl group at the other end
What is the length of a carbon chain?
14-24 carbons
What is saturation?
– refers to the number of H atoms the carbons in the fatty acid are holding
– max number of H, without carbon-carbon double bonds = saturated fatty
acid (SFA)
– SFA do not have double bonds in between the long hydrocarbon chain
What is unsaturated?
– addition of a double bond in between the long hydrocarbon chain, where
2 hydrogen atoms are missing
– 1 double bond, monounsaturated fatty acid (MUFA)
-– more than 1 double bond (more than 4 hydrogen atoms are missing),
polyunsaturated fatty acid (PUFA) (e.g. linoleic acid in plant seeds and
oils)
Location of double bond
Count from methyl end
true or false: Two fatty acids cannot be synthesized in the body
true: it needs to be obtained in the diet
Where is alpha-linolenic acid found in?
flaxseed and flaxseed oil
Where is EPA and DHA that is made from ALA fouund?
fatty fish and fish oils
What are the three subclasses of lipids found in food and in the human body?
- Triglycerides
- Phospholipids
- Sterols (cholesterol)
What are trigluycerides?
- Chief form of fat in foods: 95%
of all fats consumed in our diet - Major storage form of fat in the
body - They are composed of – Three fatty acid molecules
What makes up a triglyceride?
three fatty acid molecules and one glycerol molecule
What is glycerol made up of?
3-carbon alcohol that is the backbone of a triglyceride
What are saturated fatty acids?
- Can be packed together tightly
-Solid at room temp - Animal fats, coconut oil and butter
What are unsaturated fatty acids?
-Do not stack together well
-Liquid at room temp
-Plant oils
What is high in monosaturated fats?
Olive oil and canola oil.
What are high in polyunsaturated fats?
safflower and sunflower and corn oil -> High in omega-6
What is hydrogenation?
The addition of hydrogen atoms to monounsaturated or polyunsaturated fatty acids
- Converts liquid fat into solid
-Creates trans fatty acids
What is an example of a naturally occuring trans-fatty acid?
Conjugated linoleic acid
What is a phospholipid?
- Major component of cellular membrane
Hydrophilic
soluble in water (head group)
Hydrophobic
soluble in lipid (fatty acid tails)
What percentage does phospholipids and sterols make up of dietary lipids?
5%
What is the most common phospholipid?
Lecithin
What is lecithin made up of?
glycerol with two fatty acids and a phosphate group and a molecule of choline
Lecithin is used as what by the food industry?
An emulsifier (chocolate, margarine)
What is a sterol?
Lipids containing multiple rings of carbon atoms
What are the main functions of sterols?
-Emulsify fat (cholesterol in bile)
- Chemical messenger
-Bone metabolism
True or false: Most sterols are manufactured in our bodies and are not essential?
True: they are not an essential component of our diet
Where is cholesterol synthesized?
in the liver
What are plant sterols?
found naturally in fruits and vegetables, nuts, seeds and oils, legumes and in fortified foods e.g.
margarine, orange juice, yogurts etc
How much of sterols a day is good to improve blood cholesterol?
2g/day
Why are fats not digested and absorbed easily?
Since they are insoluble in water
What is limited digestion?
when fats occurs in the watery environments of the mouth or stomach
Where does most of the digestion of fats occur?
Small intestine
Digestion of lipids in mouth
- Melts hard fats
- lingual lipase secreted from sublingual salivary gland: Slight hydrolysis for most fats
Digestion of lipids in the stomach
- churning action mixes fat with water and acid
What is gastric lipase?
access and hydrolyses a small amount of fat
Digestion of lipids in the small int.
– bile emulsifies fat (bile
release from gallbladder
triggered by Cholecystokinin CCK)
What breaks down emulsified fat?
pancreatic and intestinal lipase
- triglycerides into glycerol and fatty acids
What happens when fat and cholesterol are trapped in fibre?
exits in poop
What is enterocyte?
Absorbs digestive products
True or false: Medium and short-chain fatty acids absorbed in the small intestine
False: they are absorbed directly into the blood
Where do short and medium-chain fatty acids move through?
move through the enterocyte and evert circulation through the capillaries
Where are short and medium-chain fatty acids transported?
they are transported by the protein albumin and they will be carried to the liver by the portal vein
How are chylomicrons transported?
they are too large to fit through the pores in the capillaries so they are transported through the lymphatic system
What do lipids bundle with for transport?
proteins
What are the 4 types of lipoproteins?
- chylomicrons
- very-low density lipo (VLDL)
- low density lipo (LDL)
- high density lipo (HDL)
What are chylomicrons?
-the lipoproteins that transport lipids from the intestinal cells into the body.
What picks up chylomicron remnants?
Liver cells
What is VLDL?
the type of
lipoproteins made
primarily by liver cells to
transport lipids to adipose
and muscle tissue;
composed primarily by
triglycerides.
What is LDL?
LDL carry cholesterol
and triglycerides from
the liver to the cells of
the body (peripheral
tissues) and are
composed primarily of
cholesterol.
What is HDL?
the type of
lipoproteins that
transport cholesterol
back to the liver from
peripheral cells;
composed primarily of
protein.
Total lipid DRI
20%-35% of daily caloric intake
important source of energy (9 kcal/g)
n-6 fatty acids
essential fatty acid (linoleic acid)
DRI: 5%-10% of daily caloric
intake (11-22 g in 2000 kcal
diet)
n-3 fatty acids
essential fatty acid along with DHA and EPA
DRI: 0.6%-1.2% of total daily caloric
intake (2.2 g in 2000 kcal diet)
What is good about fatty acids omega-3?
potent protectors against heart disease
Benefits of EPA and DHA?
1.protect heart health
2. lower blood triglycerides
3. prevent blood clots
4. lower BP
5. Defend against inflammation
Where is cholesterol only found?
animal products (eggs, beef)
What is the recommended amount of cholesterol for healthy people?
300mg/day
Where does cholesterol leave liver?
- incorporated into bile, stored in
gallbladder and delivered to intestine - Transported to all body cells via the
bloodstream
- Transported to all body cells via the
