Lipid Digestion and Absorption L3

• Gastric lipase is a digestive enzyme secreted in the mouth, but it starts working in the stomach due to the requirement of an acidic medium.
• Small intestine is where the main lipid digestion takes place, with the enzymes produced in the pancreas being the primary contributors.
• The key enzymes involved in lipid digestion in the small intestine are: Pancreatic Lipase, Co-lipase, Cholesterol esterase, Phospholipase A2, and Lysophospholipase.
• Pancreatic lipase is responsible for breaking down triacylglycerides into fatty acids and glycerol, with co-lipase aiding in its activity. Cholesterol esterase hydrolyzes cholesterol esters into free cholesterol and fatty acids. Phospholipase A2 acts on phospholipids to produce lysophospholipids and free fatty acids, while lysophospholipase converts lysophospholipids into glycerophospholipids and fatty acids.
• Lipases in the stomach (gastric lipase and lingual lipase) hydrolyze the triacylglycerides with short to medium chain fatty acids, enabling their digestion and absorption.
• Neonates and patients with pancreatic insufficiency rely on acid lipases for milk fat digestion due to their inability to produce or absorb sufficient pancreatic secretions.
• Bile salts play a crucial role in the digestion process by emulsifying dietary lipids, increasing their surface area, and making them available for enzyme digestion.
• Pancreatic lipase and co-lipase are essential for the degradation of triacylglycerides, while cholesterol esterase is responsible for cholesterol ester degradation. Phospholipids are digested by phospholipase A2 and lysophospholipase.
• Pancreatic insufficiency, commonly observed in cystic fibrosis, is caused by defective CFTR (cystic fibrosis transmembrane conductance regulator) and results in decreased secretion of chloride, increased reabsorption of sodium and water, and the thickening of pancreatic secretions, which eventually blocks the pancreatic duct, preventing the enzymes from reaching the intestine and causing malnutrition.
• Cholecystokinin (CCK) and secretin are two hormones that control the lipid digestion process by stimulating the release of bile and pancreatic enzymes, decreasing gastric motility, and neutralizing the pH of the small intestinal contents.

Explore the biochemical aspects of lipid digestion, including organs involved, enzymes required, and end products. Study the synthesis, secretion, and fate of chylomicron, as well as the clinical manifestations of diseases related to lipid digestion and absorption.