How Nutrients Become You!

The Process of Digestion Digestion is the process by which your body breaks down food, and the nutrients in food, into simpler substances. The blood can then carry these simple substances to cells for use in growth, repair, and maintenance.

Digestion It occurs through mechanical and chemical means throughout the digestive system. Mechanical digestion happens as food is crushed and churned. In chemical digestion, food is mixed with powerful acids and enzymes.

Gastrointestinal (GI) Tract As food is digested, it passes through a muscular tube leading from the mouth to the anus. This tube is called the GI tract. The GI tract is 25 to 30 feet in length. Each section performs important functions.

The Mouth Food enters the GI tract through the mouth.

Mastication Mastication, or chewing, is the first step in the digestive process. The teeth and tongue work together to move food and crush it into smaller pieces. The process prepares food for swallowing.

The Tongue You have about 9000 taste buds that cover the surface of the tongue. They sense the flavor in food. This triggers salivary glands in your mouth.

Saliva Saliva is a mixture of about 99% water plus a few chemicals. Without saliva, your mouth is dry and food seems to have little taste. Saliva moistens, softens, and dissolves food. It also helps clean the teeth and neutralize mouth acids.

The Esophagus As you chew, the muscles of your mouth and tongue form the food into a small ball. The tongue moves the food particles to the back of your mouth and you swallow. As you swallow, food passes from the mouth to the stomach through the esophagus, which is about 10 inches long.

The Esophagus

The Esophagus The esophagus is one of two tubes in the throat, the other is the trachea (windpipe). When you swallow food, a flap of skin called the epiglottis closes to keep food from entering the trachea. Breathing automatically stops when you swallow food to help prevent choking. ***Cracker Activity

Peristalsis A series of squeezing actions by the muscles in the esophagus, known as peristalsis helps move food through the GI tract. Peristalsis is involuntary – you have no control. It occurs throughout the esophagus and intestine to help mechanically move and churn food.

In the Stomach When you eat, the stomach produces gastric juices to prepare for digesting the food. Gastric juices contain hydrochloric acid, digestive enzymes, & mucus.

Gastric Juices The mixture of gastric juices with chewed and swallowed food combine in the stomach. This mixture is called chyme.

Mucosa The stomach has a thick wall lining called the mucosa. The mucosa secretes mucus. This is a thick fluid that helps soften and lubricate food and it helps protect the stomach from its strong acidic juices. The acid in the stomach is almost as strong as battery acid found in a car.

Stomach Most people can hold about 1 quart of food in their stomachs. Food generally remains in the stomach for 2 to 3 hours. Liquids leave before solids.

Small Intestine About 95% of digestion occurs in the small intestine. The small intestine is coiled in the abdomen in circular folds It has 3 sections Duodenum Jejunum ileum

Duodenum The first section of the small intestine and about 12 inches long

Jejunum The middle section and about 4 feet long.

Ileum The last section which is about 5 feet in length

Food Travel It takes 5 to 14 hours for food to travel from the mouth through the small intestine. Peristalsis helps move food through this process. The small intestine needs less acid than the stomach to break down food.

The Pancreas The pancreas, an elongated gland behind the stomach, helps create the correct environment for digestion. It secretes bicarbonate, which neutralizes hydrochloric acid that has come from the stomach with the partially digested food.

The Liver It produces a digestive juice called bile Bile aids in fat digestion and it helps disperse fat in the water-based digestive fluids Bile gives these fluid access to fats so they can break it down Bile is stored in the gallbladder and secreted into the first part of the small intestine

Large Intestine Sometimes called the colon Measures about 3 ½ feet in length in your body but about 5 or 6 feet if stretched out Its main job is to reabsorb water

Digestive Disorders Diarrhea Constipation Indigestion Heartburn Ulcer Gallstones Diverticulosis