digestion of lipids

• lipids are hydrolysed by lipase with the help of bile salts
• lipase enzymes catalyse the breakdown of lipids into monoglycerides and fatty acids. this involves the hydrolysis of ester bonds
• lipases are made in the pancreas, they work in the small intestine
• bile salts are produced by the liver and emulsify lipids - they cause the lipids to form small droplets
• several small lipid droplets have a bigger surface area than a single large droplet
• the formation of small droplets greatly increases the surface area of lipid that's available for lipases to work on
• once the lipid has been broken down, the monoglycerides and fatty acids stick with the bile salts to form tiny structures called micelles
• big lipid droplet + bile salts > emulsification = small lipid droplets > lipase digestion of lipid > micelles (monoglycerides and fatty acids)
• bile salts bind to the fatty liquid and break the droplets into smaller ones via emulsification
• micelles help to move monoglycerides and fatty acids towards the epithelium for absorption
• 1. micelles contain bile salts, fatty acids and monoglycerides
  2. micelles bring fatty acids and monoglycerides to the cell lining of the ileum
  3. fatty acids and monoglycerides absorbed by diffusion
  4. triglycerides and then reformed in the cells at the endoplasmic reticulum and golgi apparatus
  5. vesicles then move to cell membrane
• golgi apparatus processes triglycerides and combines them with proteins. vesicles are formed and the triglyceride is transported to the cell membrane
• droplets being formed increases the surface area for lipase action, so faster hydrolysis of lipids
• micelles carry fatty acids and monoglycerides to the epithelial cell