Once inside the adipose cells, the fatty acids and glycerol are reassembled into triacylglycerols and stored for later use. Muscle cells may also take up the fatty acids and use them for muscular work and generating energy. As the body calls for additional energy, the adipose tissue responds by dismantling its triacylglycerols and dispensing glycerol and fatty acids directly into the blood.
Upon receipt of these substances the energy-hungry cells break them down further into tiny fragments. These fragments go through a series of chemical reactions that yield energy, carbon dioxide, and water. Learning Objectives Summarize the steps in lipid digestion and absorption.
Explain how lipids are used for energy and stored in the body. From the Mouth to the Stomach The first step in the digestion of triacylglycerols and phospholipids begins in the mouth as lipids encounter saliva. Going to the Bloodstream As stomach contents enter the small intestine, the digestive system sets out to manage a small hurdle, namely, to combine the separated fats with its own watery fluids.
The Truth about Storing and Using Body Fat Before the prepackaged food industry, fitness centers, and weight-loss programs, our ancestors worked hard to even locate a meal. Key Takeaways In the stomach fat is separated from other food substances. In the small intestines bile emulsifies fats while enzymes digest them.
The intestinal cells absorb the fats. Long-chain fatty acids form a large lipoprotein structure called a chylomicron that transports fats through the lymph system.
Chylomicrons are formed in the intestinal cells and carry lipids from the digestive tract into circulation. Short- and medium-fatty chains can be absorbed directly into the bloodstream from the intestinal microvillus because they are water-soluble.
Cholesterol absorption is hindered by foods high in fiber. When energy supplies are low the body utilizes its stored fat reserves for energy. Discussion Starters Explain the role of emulsifiers in fat digestion. Name the part of the digestive system where most fat digestion and absorption occurs. Describe the role of bile salts in the digestion of triacylglycerols and phospholipids.
Define chylomicron. Explain how fiber-rich foods affect cholesterol absorption. Is that why we feel lighter after doing our business? Are we actually losing weight? It turns…. Does muscle really weigh more than fat?
Several natural foods and beverages have been shown to increase metabolism and promote fat loss. These 11 healthy foods can help you burn fat. Belly fat is the most harmful fat in your body, linked to many diseases. Here are 6 simple ways to lose belly fat that are supported by science. High triglycerides can have many causes, including genetics.
When it's an inherited condition, it's known as familial hypertriglyceridemia. HDL cholesterol removes extra cholesterol and plaque buildup in your arteries. High cholesterol often has no symptoms, but can lead to serious health issues. Health Conditions Discover Plan Connect. Dietary fats consist of: saturated fat trans fat monounsaturated fatty acids polyunsaturated fatty acids, including omega-3 fatty acids Trans and saturated fats are considered unhealthy fats and raise LDL cholesterol.
How is fat digested? What happens after the fat is digested? Can you improve the fat digestion process? Fat recommendations. Read this next. What to Know About Familial Hypertriglyceridemia. Such coating with bile acids aids in breakdown of large aggregates or droplets into smaller and smaller droplets.
Hydrolysis of triglyceride into monoglyceride and free fatty acids is accomplished predominantly by pancreatic lipase.
The activity of this enzyme is to clip the fatty acids at positions 1 and 3 of the triglyceride, leaving two free fatty acids and a 2-monoglyceride. The drug orlistat Xenical that is promoted for treatment of obesity works by inhibiting pancreatic lipase, thereby reducing the digestion and absorption of fat in the small intestine.
Lipase is a water-soluble enzyme, and with a little imagination, it's easy to understand why emulsification is a necessary prelude to its efficient activity. Shortly after a meal, lipase is present within the small intestine in rather huge quantities, but can act only on the surface of triglyeride droplets. For a given volume of lipid, the smaller the droplet size, the greater the surface area, which means more lipase molecules can get to work.
As monoglycerides and fatty acids are liberated through the action of lipase, they retain their association with bile acids and complex with other lipids to form structures called micelles.
Micelles are essentially small aggregates nm in diameter of mixed lipids and bile acids suspended within the ingesta.
As the ingesta is mixed, micelles bump into the brush border of small intestinal enterocytes, and the lipids, including monoglyceride and fatty acids, are taken up into the epithelial cells. The major products of lipid digestion - fatty acids and 2-monoglycerides - enter the enterocyte by simple diffusion across the plasma membrane. A considerable fraction of the fatty acids also enter the enterocyte via a specific fatty acid transporter protein in the membrane.
Lipids are transported from the enterocyte into blood by a mechanism distinctly different from what we've seen for monosaccharides and amino acids. Once inside the enterocyte, fatty acids and monoglyceride are transported into the endoplasmic reticulum, where they are used to synthesize triglyeride. Beginning in the endoplasmic reticulum and continuing in the Golgi, triglyceride is packaged with cholesterol, lipoproteins and other lipids into particles called chylomicrons.
Remember where this is occurring - in the absorptive enterocyte of the small intestine.
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