The Digestive System What is digestion The process

The Digestive System

What is digestion? The process by which your body breaks down food, and the nutrients in food, into simpler substances.

Where does digestion start?

Mouth Mastication, or chewing, starts the digestive process. Odors and taste from food activate salivary glands and produce saliva. Saliva is 99% water, but it also has a few chemicals in it. One chemical present in saliva is the enzyme salivary amylase. Salivary amylase starts the breakdown of starches.

Define Enzyme A substance produced by a living organism that acts as a catalyst to bring about a specific biochemical reactions.

Define Catalyst A substance that increases the rate of a chemical reaction without itself undergoing any permanent chemical change.

Esophagus As you swallow, food passes from the mouth to the stomach through the esophagus. A flap of skin called the epiglottis closes to keep food out of the trachea (windpipe). A series of squeezing actions by the muscles in the esophagus, known as peristalsis, help move food through the tube.

Stomach The stomach produces gastric juices that contain hydrochloric acid (HCl), digestive enzymes, and mucus. When mixed with food, the mixture is called chyme. The mucus in the stomach helps soften and lubricate food. It also helps protect the stomach from its strong acidic juices (almost as strong as battery acid). Protein digestion starts in the stomach. The major enzyme that helps break down protein is pepsin.

In what order do foods leave the stomach? Food remains in the stomach for 2 -3 hours. Then is starts to leave in this order: 1. Liquids 2. Carbohydrates 3. Proteins 4. Fats In what order would this meal digest? A turkey sandwich (bread, turkey, tomato, lettuce, mayonnaise) A glass of milk An orange

Small Intestine The small intestine has 3 different sections: duodenum: 12 inches jejunum: 4 feet ileum: 5 feet It takes about 5 -14 hours for food to travel from the mouth through the small intestine. Peristalsis moves food through the small intestine.

3 organs aid in digestion in the small intestine. 1. Pancreas: helps create a less acidic environment for digestion in the small intestine. It secretes bicarbonate (base), which neutralizes the HCl (acid) coming from the stomach. The pancreas also produces digestive enzymes that break down proteins, carbs, and fats into their most basic parts. 2. Liver: produces the digestive juice called bile. Bile aids in fat digestion by helping disperse the fat in the water-based digestive fluids. This gives enzymes access to the fat to help break it down. 3. Gallbladder: Bile is stored in the gallbladder until it is needed.

What is absorption? The passage of nutrients from digestive tract into the: Circulatory System Lymphatic System

Absorption The inside of the small intestine is about 600 times larger than a smooth surface because of the thousands of folds. These folds are covered with villi. Each villus is covered with microvilli which are microscopic hairs that help catch nutrient particles. Water soluble nutrients are absorbed into the bloodstream through the capillaries--the blood vessels in the villi. Fat soluble nutrients are absorbed into the lymphatic system through the lymph vessels in the villi,

Large Intestine/Colon Very little digestion occurs in the colon. Chyme is very liquid when it enters and stays about 1 -3 days before elimination. During this time, water is absorbed through the walls of the colon and useful bacteria work on fiber as well as help manufacture small amounts of vitamins. Solid wastes are called feces and include: mucus, bile pigments, fiber, sloughed off cells from the lining of the colon, and water. The end of the large intestine is called the rectum. This is we're feces are collected

Metabolism All the chemical changes that occur as cells produce energy and materials needed to sustain life. Through metabolism, cells convert some nutrients into energy. The body stores this energy as ATP (adenosine triphosphate). ATP is the source of immediate energy found in muscle tissue.

Factors Affecting Digestion and Absorption Eating Habits Eat a variety of foods to insure proper digestion. Also include lots of fresh fruits, vegetables, and whole grain products. These are high in fiber and help strengthen intestinal muscles. Take your time when you eat. Eating too quickly can put stress on your digestive system and it can no longer function most Emotions Fear, anger, and tension can lead to digestive difficulties. Food Allergies and Intolerances Allergy - reaction from body’s immune system. The body produces antibodies to protect the body from foreign materials. Symptoms of an allergic reaction are vomiting, stomach pain, intestinal stress, skin rashes, swelling, and breathing problems. Intolerance - usually requires a larger amount of food. They are caused by deficiencies or reactions in the digestive tract. Symptoms can be similar to allergies, but they can also include elevated blood pressure, Physical Activity Stimulates a healthy appetite Strengthens the muscles of internal organs Move food brought the GI tract. Reduces stress and adds to overall sense of wellbeing.

Digestive Disorders Explain what the disorder is and how it is treated or prevented.