Lecture 9: Lipid metabolism :
• Fats - calorically dense - 9kcal/gram
• However these molecules must be metabolized aerobically in the Mitochondria.
• Slowest form of energy production because they need to be liberated either from
adipose tissue or the liver. In addition the process takes much longer than metabolizing
• Hydrophobic molecules, therefore they need to be transported by something in order to
get through the polar blood.
• Adipose cells 95% triglycerides
• These are virtually an inexhaustible form of energy
Consumption to absorption in intestinal cells:
1. Consume dietary fat
2. Large triglyceride droplet forms - so that it does not touch the water
3. Bile salts are added to break up the triglycerides - emulsification ( this increases the
surface area of the lipids, creating smaller fat molecules)
4. Emulsification allows for the pancreatic lipase to hydrolyze the triglycerides into
monoglycerides and free fatty acids.
5. Bile salts are added forming micelles which aid in the absorption of the monoglycerides
and free fatty acids.
6. After passive diffusion of the monoglycerides and free fatty acids into the intestinal cell
they are resynthesized into triglycerides -esterification
7. They aggregate and are coated with a lipoprotein to form water soluble chylomicrons.
8. These are then extruded from the basal membrane - exocytosis.
9. Put into lymph tissue because chylomicrons cannot diffuse into the