What is the process of fat absorption in the intestine?

Fat absorption in the intestine involves emulsification, hydrolysis, micelle formation, and absorption into enterocytes.

In the small intestine, dietary fats undergo a process of digestion and absorption. The first step in this process is emulsification, which is facilitated by bile salts produced by the liver and stored in the gallbladder. Bile salts surround fat droplets and break them down into smaller droplets, increasing the surface area for the action of digestive enzymes. This process is crucial as it allows lipase, an enzyme produced by the pancreas, to effectively break down the fats.

The next step is hydrolysis, where pancreatic lipase breaks down triglycerides, the main dietary fat, into monoglycerides and free fatty acids. This process is aided by co-lipase, another enzyme produced by the pancreas, which binds to lipase and allows it to anchor onto the fat droplet surface.

Following hydrolysis, the monoglycerides and free fatty acids form complexes with bile salts, creating structures known as micelles. Micelles are tiny, spherical complexes that are soluble in water, allowing them to move freely in the watery environment of the small intestine.

The final step in fat absorption is the uptake of micelles by the enterocytes, the cells lining the small intestine. The micelles come into contact with the enterocyte membrane, where they release their contents. The monoglycerides and free fatty acids then diffuse into the enterocytes. Once inside, they are reassembled into triglycerides and packaged with proteins and cholesterol into particles called chylomicrons.

The chylomicrons are then released into the lymphatic system, bypassing the liver, and eventually enter the bloodstream, where they deliver triglycerides to the body's cells for energy use or storage. This comprehensive process ensures that the body can effectively utilise the fats consumed in the diet.