Lipids Flashcards
What are lipids?
A compound that is souble in a ORGANIC solvent, but insoluble in water or hydrophobic.
What is the function of lipids?
Provision of energy, structure and cell signaling.
Function of lipids .2
Provide calories needed to meet the body’s energy needs.
Function of lipids .3
Source of essential fatty acids needed for cell membranes, skin, cardiovascular and brain health.
Why is phospholipids important?
Phospholipids are essential for the structure of cell membranes and form membrane of lipoproteins -> make transport of lipids in the blood possible.
Functions of lipids:
Maintain body temperature, absorption of fat-soluble vitamins (A,D,E,K),
What is Adipose tissue?
The site of fat storage in the body –> excess triglycerides are stored –> needed for energy during fasting.
What is cholesterol?
Used to produce steroid hormones (oestrogens & androgens), bile acids, vitamin D and glucocorticoids (cortisol)
Types of Lipids?
Triglycerides, phospholipids, sterols.
What is triglycerides?
Composed of three fatty acids eterified to a glycerol backbone.
Fatty acid is a chain of..
methyl (CH3-) and carboxyl (-COOH) end
How are fatty acids characterized?
By their degree of saturation and length of the carbon chain.
Short chain?
2-6 carbons
Medium-chain?
7-14 carbons
Long-chain
> 14 carbons
Longer-chain
20-26 carbons
Example of organic solvent
Oil, alcohol and etanol.
DIffer in: Chain length (no.of carbons)
Higher melting point
Differ in: unsaturation (no. of double bonds)
Lower melting point
Differ in: position and geometry (cis or trans) of double bonds.
All health effects.
What does it mean when a fatty acid is saturated?
All the carbons in the chain have hydrogen atoms for each available bond –> no double bonds
What does it mean when a fatty acid is unsaturated?
Has at least ONE carbon missing a hydrogen atom –> causing a double bond to form.
What is essential fatty acid?
Fatty acids that cannot be synthesized by the body and must be consumed in the diet.
Example of essential fatty acid?
Linoleic acid (18:2;w-6) and a-linolenic acid (18:3;w-3)
What does phospholipid have?
Two fatty acids & phosphate group.
What does phospholipids form?
Form a lipid bilayer –> key for the structure of cell memebranes
The phospholipid head is…
Hydrophilic
The 2 fatty acids are..
Hydrophobic
Structure of sterols:
Four-membered ring
The sterol in humans is?
Cholesterol
Foods high in unsaturated fat:
Nuts, seeds, olives/olive oil and avocados
Foods high in monounsaturated fat
Olive oil, almond, avocados
Foods high in polyunsaturated fat
Nuts, seeds, vegetable oils, oily fish
Where do we find TRANS unsaturated fatty acids?
Present in very small amount in dairy products
How is trans fat created?
Hydrogenation –> double bonds in unsaturated fatty acids are changed from the cis to trans –> making vegetable oil into solid fat.
Where do we find trans fat?
Margarines, snack foods and prepared desserts.
How many percent of dietary fat is absorbed
90-95%
What is absorbed direcly into the blood?
Glycerol and small-& medium - chain fatty acids.
What is absorbed into the enterocytes?
Long-chain fatty acids, cholesterol and monoglycerides.
What is not soluble in water?
Fat
Lipid transport: how is triglycerides packaged?
Packed along with cholestrol and phospholipids into CHYLOMICRONS.
How does chylomicrons transport triglycerides?
From the enterocyte to the muscle and adipose tissues.
Lipid transport: What happens if the body is at rest?
Triglycerides are taken up by adipose tissue for storage.
Lipid transport: What happens if the body is active?
Muscle tissue will oxidize fatty acids to provide energy –> Beta-oxidation
How is lipoproteins classified?
By their density
The density names:
VLDL (very low-density lipoproteins), LDL (low-density lipoproteins) and HDL (high-density lipoproteins)
VLDL transport:
Triglycerides from the liver to the muscle & adipose tissue.
LDL transport:
Cholestrol from the liver to body tissues.
HDL transport:
Cholestrol from the tissues back to the liver.
What is essential fatty- acid deficiency:
A issue that can arise from a severe restriction of fat intake.
What cannot be synthesized by the human body?
The long-chain omega-3 and omega-6 fatty acids.
What are the symptoms of deficiency?
Poor wound healing, visual problems, neuropathy, susceptibility to infection, decreased growth in children.
The most prevalent outcome of excess caloric intake from fat
Obesity
High fat intake and high saturated fat intake can cause:
various cancers (colorectal & breast cancer)
Reduction in saturated fat intake can result in?
14% reduction in cardiovascular risk.
