• Dietary lipids: TAGs, phospholipids, and cholesterol esters
  • Not readily absorbed by enterocytes due to:
    • Hydrophobic properties
    • Large molecular size
  • First broken down by lipases in the mouth, stomach, and intestinal lumen and packaged into micelles
  • Micelles
    • A spherical-shaped aggregation of surfactant molecules in a colloid
    • Composed of an outer layer of hydrophilic (polar) heads and an inner hydrophobic (nonpolar) core
    • Enclose lipids and fat-soluble vitamins, forming a package
    • Readily absorbed by the membranes of enterocytes → deliver internal contents to the cell
• Bile release: Once a lipid enters the intestinal lumen, bile is secreted into the lumen to emulsify the lipid contents.
  • Emulsify: mechanically disrupt these large fat globules into smaller droplets, increasing the surface area exposed to digestive enzymes like pancreatic lipase.
• Pancreas secretion: The pancreas secretes pancreatic lipase, colipase, and cholesterol esterase, which hydrolyze the lipid into cholesterol, fatty acids, and 2-monoglyceride molecules.
• Absorption of short-chain and medium-chain fatty acids: pass the enterocytes → released to the hepatic portal vein → liver → enter the general circulation and bind albumin