Where is lipids broken down

Here, the fat components are released and disseminated into the cells of the digestive tract lining. Figure 4. Just as lipids require special handling in the digestive tract to move within a water-based environment, they require similar handling to travel in the bloodstream.

Inside the intestinal cells, the monoglycerides and fatty acids reassemble themselves into triacylglycerols. Triacylglycerols, cholesterol, and phospholipids form lipoproteins when joined with a protein carrier. Lipoproteins have an inner core that is primarily made up of triacylglycerols and cholesterol esters a cholesterol ester is a cholesterol linked to a fatty acid. The outer envelope is made of phospholipids interspersed with proteins and cholesterol.

Together they form a chylomicron, which is a large lipoprotein that now enters the lymphatic system, bypassing the liver, and will soon be released into the bloodstream via the jugular vein in the neck. Entrance into the bloodstream can last up to 14 hours with the peak 30 to 3 hours post-meal.

Cholesterols are poorly absorbed when compared to phospholipids and triacylglycerols. Cholesterol absorption is aided by an increase in dietary fat components and is hindered by high fiber content. This is the reason that a high intake of fiber is recommended to decrease blood cholesterol. Foods high in fiber such as fresh fruits, vegetables, and oats can bind bile salts and cholesterol, preventing their absorption and carrying them out of the colon.

If fat malabsorption persists the condition is known as steatorrhea. Fat cells are located in special depots in your body and there are many different locations, for example, abdominal belly fat or the hips. Also, a small amount of fat is stored in skeletal muscle too. See Figure 4. Once stored in the adipocyte fat cell , the fat will remain there until it is needed to produce energy. Lipolysis is the process by which the triacylglyceride is removed from the lipid droplet with the fat cells, broken into 3 fatty acids and glycerol.

The glycerol is secreted from the cells along with some but not all of the fatty acids. These are transported to the liver where the glycerol may be converted to glucose. The fatty acids may be converted to ketones or transported to other cells and burn to produce ATP. Before the prepackaged food industry, fitness centers, and weight-loss programs, our ancestors worked hard to even locate a meal. They made plans, not for losing those last ten pounds to fit into a bathing suit for vacation, but rather for finding food.

Today, this is why we can go long periods without eating, whether we are sick with a vanished appetite, our physical activity level has increased, or there is simply no food available. Our bodies reserve fuel for a rainy day. One way the body stores fat involves the body transforms carbohydrates into glycogen that is in turn stored in the muscles for energy. Structure of a chylomicron. Cholesterol is not shown in this figure, but chylomicrons contain cholesterol in both the lipid core and embedded on the surface of the structure.

Yet, infants are born with low levels of bile and pancreatic enzyme secretion, which are essential contributors to lipid digestion in older children and adults.

So, how do babies digest all of the fat in their diet? Infants have a few special adaptations that allow them to digest fat effectively. First, they have plenty of lingual and gastric lipases right from birth.

These enzymes play a much more important role in infants than they do in adults. In other words, the mother makes lipases and sends them in breast milk to help her baby digest the milk fats. Amazing, right? Between increased activity of lingual and gastric lipases and the lipases contained in breast milk, young infants can efficiently digest fat and reap its nutritional value for growth and brain development. Studies show that fat digestion is more efficient in premature infants fed breast milk compared with those fed formula.

Even pasteurized breast milk, as is used when breast milk is donated for feeding babies in the hospital, is a little harder to digest, because heat denatures the lipases. Skip to content Lipid digestion and absorption pose some special challenges. Next: Lipid Transport, Storage, and Utilization. Share This Book Share on Twitter. They are just special proteins that can break large molecules into small molecules.

Different types of enzymes can break down different nutrients:. Carbohydrates are digested in the mouth , stomach and small intestine. Carbohydrase enzymes break down starch into sugars. The saliva in your mouth contains amylase, which is another starch digesting enzyme. If you chew a piece of bread for long enough, the starch it contains is digested to sugar, and it begins to taste sweet.

Proteins are digested in the stomach and small intestine. Protease enzymes break down proteins into amino acids. Digestion of proteins in the stomach is helped by stomach acid , which is strong hydrochloric acid.