Question

Describe the journey of fats through the human digestive system.

Answer 1

The digestive system plays an important role in the absorption ofnutrients into the body. It takes the food we ingest, breaks it down mechanically and chemically in the mouth and stomach. It then absorbsnutrients, fats, proteins and water in the intestines before eliminating the waste through the rectum

Answer 2

The process of digestion starts in the mouth, although fat does not get broken down at this point. Mechanical digestion occurs as your teeth grind food and break it apart into smaller pieces. Chemical digestion takes place as lingual lipase, an enzyme in your saliva, begins to emulsify fat and saliva moistens the food to make it easier to swallow.When the food reaches your stomach, the muscles there begin to churn and move to further break it down. Once it leaves the stomach, the food has become a semi-liquid substance referred to as chyme.The small intestine is the main site for absorption of nutrients and the digestion of fat. When chyme enters the duodenum -- the upper portion of the small intestine -- hormones signal the gallbladder to contract. These contractions push bile, which is made by the liver, out of the gallbladder and into the common bile duct, which connects the gallbladder to the small intestine. At the same time, the pancreas, located just underneath the stomach, secretes bicarbonate ions, which neutralize the pH of the chyme entering the small intestine, and lipases, enzymes that break down fat.Fats are hydrophobic, which means they do not dissolve in water. Left to their own devices, fat molecules would clump together and form one big fat molecule that is not easily digested. Bile prevents this from happening. Bile molecules have a hydrophobic, or water-fearing, end and a hydrophilic, or water-loving, end. The hydrophobic end sticks to each fat molecule and the hydrophilic protrudes to prevent the molecules from sticking together. The combined structures of fat molecules and bile molecules are called micelles.Once fat molecules become micelles, lipases go to work, breaking down fat molecules into fatty acids and monoglycerides, which pass through the small intestine. After they pass through the small intestine, fatty acids are converted to triglycerides, which combine with cholesterol, phospholipids and protein to form a structure called a chylomicron. The protein coating of the chylomicron makes it water-soluble so it can travel through the lymph vessels and eventually the bloodstream.