4. digestion - Lipids Flashcards
1
Q
outline the process of lipid digestion
A
- large fat droplet is broken down by bile (emulsifier) into smaller components (triacylglycerides)
- triacylglyceride broken down by pancreatic lipase to form triangular shape to form micelles
- micelles get absorbed into cell
- transported into golgi then ER and resynthesised into TAG
- made into a chylomicron (made of TAGs lipids, cholesterols proteins etc) by ER
- apolipoprotein main protein in chylomicron to make a hydrophilic shell to be stable in blood
- chylomicron leaves cell via exocytosis into lacteal (lymphatic circ) then bloof via thoracic duct (bypassing hepatic metabolism)
- as they travel through systemic circulation, TAG taken up by cells
2
Q
name the major constituents of bile and their functions in digestion
A
- water: makes up the bulk of bile and acts as a medium to dissolve and transport the other components. It facilitates the flow of bile through the bile ducts into the small intestine.
-
bile salts: break down large fat globules into smaller micelles, increasing the surface area for the action of pancreatic lipase
-** bilirubin**: waste product from the breakdown of hemoglobin. It is excreted in bile and gives bile its yellow-green color.not directly involved in digestion - phospholipids: Phospholipids aid in the emulsification process. They stabilize the micelles formed by bile salts, helping to keep fats in a digestible form
- cholesterol: Cholesterol is a component of bile and serves as a precursor for bile salt synthesis. doesnt directly aid in digestion
- electrolytes: help maintain the pH of bile
3
Q
why is TAG broken into 2 monoacylglyceride and then resynthesized into TAG
A
monoacylglyceride is more easily absorbed by enterocytes
TAGs are resynthesized to enable their packaging into chylomicrons, which are suitable for transport through the lymphatic system. this is more efficient for transport and storage
4
Q
what enzyme stimulates bile secretion into the intestine
A
CCK
