Journey of Fat Digestion

Overview

• Follow the journey of fat from a cheeseburger.
• Focus on digestion, transportation, and storage in the body.

Initial Digestion

1. Mouth
   • Chewing breaks down the food.
2. Esophagus
   • Food travels down to the stomach.
3. Stomach
   • Churning and mixing with stomach acid.
4. Small Intestine
   • Main site for nutrient absorption, including fats.

Absorption in Small Intestine

• Lined with specialized epithelial cells (nutrient absorption).
• Contains enzymes called lipases (break down fats).
• Lipases require an aqueous environment, but fats are hydrophobic.

Role of Bile

• Bile (from the liver) acts like a detergent.
• Emulsifies fats, increasing surface area for lipases to act.
• Lipases cleave triacylglycerides (TAGs) into glycerol and fatty acids.

Reforming TAGs and Formation of Chylomicrons

1. Small Intestine Cells
   • Reform TAGs.
2. Lipoproteins
   • Pack TAGs into lipoproteins.
   • Chylomicron: a type of lipoprotein used for transport.

Transport to Tissues

1. Lacteals (lymphatic capillaries)
   • Chylomicrons are transported here.
2. Lymphatic Vessels
   • Travel through lymphatic vessels to regions near the neck/shoulder.
   • Empty into veins via left and right thoracic ducts.

Recap

• Digestion in the mouth, stomach, and small intestine.
• Absorption via epithelial cells with the help of bile and lipases.
• Reforming TAGs and transport as chylomicrons through the lymphatic system.
• Journey continues in the blood vessels (to be covered in the next video).