L4-Lipids Flashcards
What are considered part of the non-membrane lipids?
- Fatty acids
- Triaclyglycerols
- Steroids
- Cholesterol esters
What are considered part of the membrane lipids?
- glycerolphospholipids
- sphingolipids
- cholesterol
What does a fatty acid look like?
simplest form.
- polar, carboxylic acid head
- nonpolar, methyl group tail
What type of fatty acids is the omega naming system used for?
Long-chained polyunsaturated fatty acids
What are some examples of saturated fatty acids?
animal meats, butter, whole milk, tropical plant oils
- stearic acid
What are some examples of monounsaturated fatty acids?
olive oil, canola oil, nuts
-oleic acid
What are some examples of polyunsaturated fatty acids?
fatty fish, seeds, nuts, grains, veggies
-omega 3&6
What is the formation of trans fatty acids?
structurally similar to saturated fatty acids even with a double bond
- double bond H atoms are across from each other
What are the two essential fatty acids?
Omega 3 and omega 6
-Omega 3 is a precursor for growth and development (linolenic acid)
-Omega 6 is a precursor for arachoidonic acid
(linoleic acid)
Phytanic acid is what type of lipid?
A branched fatty acid
Contains a methyl group on the third carbon
This methyl means it is broken down through a-oxidation
What is caused by a deficiency in a-hydroxylase?
Refsum disease
- phytanic acid accumulates in the blood and tissues which causes neuronal damage
- treat with a diet low in phytanic acid
What is the storage form of fatty acids called?
Triaglycerides
What are the components of TAGs?
- 3 activated fatty acids (as fatty acylCoA)
- 1 glycerol
What is the basic structure of a steroid?
A tetracyclic ring structure
What is the basic structure of a cholesterol ester?
The polar group of cholesterol is esterified to a fatty acid
-> non polar molecule
What are the three types of amphipathic molecules?
glycerolphospholipids, sphingolipids, cholesterol
What are the hydrophobic and philic regions of glycerolphospholipids?
phobic- 2 long chain fatty acids
philic-phosphate group+alcohol
What are the phobic and philic regions of sphingomyelins
phobic- ceramide ( fatty acid+sphingosine)
philic-phosphate group plus choline
What are the phobic and philic regions of glycosphingolipids?
phobic- ceramide (fatty acid+sphingosine)
philic- carbohydrate group
What are the phobic and philic regions of cholesterol?
phobic- rigid steroid ring + nonpolar tail
philic- OH- group
What enzymes produced in the mouth and stomach breakdown fats?
lingual lipase and gastric lipase
—-> primary target are short chain FFA (
Lipids stimulate the secretion of what from the small intestine?
CCK and secretin
What is the function of CCK?
Delays gastric emptying, promotes satiety
-stimulate the release of bile sale and pancreatic enzymes
What is the function of secretin?
Stimulates the pancreas to release HCO3-
—-> neutralizes acidic chyme
What is the first step of emulsification?
spraying chyme through narrow pyloric sphincter
How do bile salts function?
They stabilize the lipid droplets in solution and prevent them from coalescing
Pancreatic lipase break TAGs down into what?
a monoglyceride and 2 fatty acids
What are mixed micelles formed of?
disk shaped clusters of amphipathic lipids
-bile salts make up the edges of the “coin”
How do micelles transport lipids to the enterocytes?
They bump into the border and dump their contents into the enterocytes but remain in the lumen to be recycled
How are TAGs and Cholesterol esters transported?
They must be reassembled and packaged into chylomicrons and enter the lymphatic system
What are chylomicrons?
Lipid droplets composed of monolayer amphipathic lipids
- the largest of the lipoproteins
-enter the blood stream 1-2 hours after a meal
(the lymphatic system drains into the blood at the thoracic duct)
How to short and medium chain FFa enter the blood stream?
They are transported to the enterocyte as is. They bind to albumin and go directly to the liver for energy metabolism
What is steatorrhea?
increased lipid in the feces
What are come causes for lipid malabsorption?
- low bile salts
- low pancreatic enzymes
- decrease in absorption
What is Olestra?
made from sucrose to which fatty acids have been esterified
-heat stable, not digested, lost in stool with other fat soluble nutrients
What is Simplesse?
Made from microparticulated proteins from milk and eggs
- not heat stable so used in ice cream
- half the calories of fat
What is orlistat (xenical/alli)?
A drug for obesity
- inhibits pancreatic lipases
- fat is then lost in the stool
