in this video we're going to talk about fat digestion and absorption fat is an important component of our diet it is both a protective and also it contributes to heart disease depending on the type of fat in its complete form the fats are made up of a lot of triglycerides and triglycerides are essentially where you have three fatty acids combined to a glycerol back bone our body needs to break down this structure into its building blocks in order to absorb it into our body and use it as we wish fat breakdown begins in the mouth with lingual lipase and mastication lipase hydrolyzes and breaks down lipids the fats the partially digested lipids travel to the stomach to be further greeted by the gastric lipase the broken down lipids are still in triglyceride chunks which move into the duodenum bringing with it the acidity from the stomach fat droplets and the acidity from the stomach will stimulate the small intestinal cells to produce two important hormones cholecystokinin cck and secretin cck stimulates bile production and secretion cck also stimulates pancreatic enzyme release known as the pancreatic juice secretin on the other hand will stimulate bicarbonate secretion from the pancreas and this is in order to raise the intraluminal ph to approximately 6.5 which is the optimum sort of environment for fat digestion so let's put it all together and look at the lipids that have just entered the small intestine and are going to be exposed to the bile and the pancreatic enzyme lipase bile specifically bile salts help with emulsification of lipids basically coating it and this allows for digestion by the pancreatic lipases pancreatic lipase will help break down the triglycerides further into fatty acids and the monoglycerides and help form what we know as micelles these micelles are essentially a ball composed of the broken down products of fat the building blocks of fat micelles are composed of bile salts the fatty acids the monoglycerides cholesterol and all this is coded also by phospholipids now in this form the monoglycerides and the fatty acids are able to be transported and absorbed across the apical membrane of enterocytes mainly in the proximal two-thirds of the jejunum which is essentially the middle part of the small intestine the bile salts themselves remain in the intestinal lumen because they do not get reabsorbed here they actually reach the terminal ileum where they are actively reabsorbed and enter the portal circulation into the liver and this cycle is known as the enterohepatic circulation entero as in intestine and hepatic as in liver so the bowel salts that are reabsorbed here and are in the liver are then essentially recycled and re-secreted into bile to be used again the fatty acids and the monoglycerides which were absorbed in the jejunum will be packaged up in the cells to form fully mature chylomicrons and these color microns will then bind to the basolateral membrane and is transported to the intestinal lymphatics and from the intestinal lymphatics it will then enter the journal general circulation to be transported around our body now it's also important to know that vitamins such as vitamins a d e and k or addic rely on fat to be absorbed in the jejunum while vitamins b and c are more water soluble and they do not rely on fat absorption or digestion so in summary fat digestion begins with lingual lipase gastric lipase until it enters a small intestine where it gets into contact with bile salts and pancreatic lipase fat is absorbed as fatty acids and monoglycerides in the jejunum the bile salts get recycled through the anterior hepatic circulation fat is packaged up as chylomicrons in the small intestine before being transported via the lymphatics into the general circulation [Music] you