Lipids Flashcards
What is the head and tail of a FA made of
Tail: hydrocarbon
Head: carboxylic acid
What are FFA bound to in blood?
Albumins
What the difference between Cis and trans bonds
Cis - chains are on the same side while trans bonds are on the opposite
Glycerol lipids
- are basically TAGS
- glycerol back bone + ester linkages
Fat digestion in the mouth
Released by sublingual salivary gland
And the enzyme released is lingual lipase
Breaks down one bound in triglycerides to produce diglyceride and Fa
Descibe the digestion of lipids in the stomach
- lingual lipase is not broken down by the stomach acid
- gastric lipase does a small amount of break down in the stomach
Describe the digestion in the small intestine
- CCK initiates release of bile acids in the stomach
- fat turns into emulsified fats
Pancreatic and intestinal lipase break down triglycerides into monglycerides, glycerol, fatty acids
Describe digestion in the large intestine
Cholesterol and some fat get trapped in fibre and get excreted
Describe the process of process of lipid emulsification
-Bile acid is released and has affinity for water and fat
- fat is in a place where it is inaccessible to lipase
- bile attaches onto fat to become emulsified in to water which make it more accessible to lipases
Lingual lipase
Sn-3
Gastric lipase
- medium chain FA
- SN-3
Pancreatic lipase
Sn-3 or 1
Pancreatic lipase A2
Hydrolzes sn-2 and PC hydrolyzes phophotidycholine and FFA
Pancreatic Cholesterol esterase
–non specific esterase
- Fatty acids on cholesterol esters, fatty acids at all positions on TG, PL, esters of fat soluble vitamins.
How does absorption occur
- Lipids must cross the unstirred water layer before being absorbed by the enterocyte.
- Mixed micelles are more soluble in the unstirred water layer and easily cross the layer.
What are the 2 processes in which lipid can be absorbed into the enterocyte
- Carrier mediated proteins on the brush border membrane
- Passive diffusion
Where is the NPC1L1?
It’s a protein in which micelles are transported across the brush border membrane into the enterocyte, it’s also a major sterol transporter
How are plant sterols absorbed?
The micelles enter the intro site via the NPC1L1 transporter intro into the enterocyte where it undergoes endosomal sorting and comes out as plant sterols add cholesterol. Then exits the intro site as plant sterols and cholesterol
What is the mechanism of action for phytosterols?
Phytosterols help lessen the cholesterol that it is absorbed into the micelles then enterocyte
Describe the enterohepatic circulation of bile salts?
When bile salts enter the large intestine, it is absorbed into the portal vein where it sent into liver. In the liver, and then goes to the gallbladder, where it is stored and concentrated for use for later.
What are the two processes the enterocyte metabolize lipids?
(I) Monoacylglycerol pathway
(II) Glycerol 3-phosphate pathway
Describe the monoacylglycerol pathway?
Once the enterocyte has monoacylglycerol absorbed into it it uses acyltransferase to add on a fatty acid in order to form a tag
Enzymes for this process are found in the endoplasmic reticulum
Describe the Glycerol 3-phosphate pathway
This process uses glycerol three phosphate to form a diacylglycerol, and then a tag. It occurs when the Meg is not functioning properly
