Digestive System Notes The Digestive Process Begins Digestion is the process by which your body breaks down food into molecules your body can use. A. Functions of the Digestive System 1. breaks down food into molecules 2. the molecules are absorbed into the blood and carried throughout the body 3. wastes are eliminated from the body Digestion Video (2 min.)

B. The Mouth – where digestion begins. Mechanical digestion in the mouth – your teeth carry out the fist stage of this type of digestion. Saliva then moistens the food and forms it into a moist, slippery, mass. Chemical digestion in the mouth – a chemical in the saliva breaks down the starch molecules in the food into sugar molecules. a. enzymes – proteins that speed up chemical reactions in the body.

C. The Esophagus is the muscular tube that connects the mouth to the stomach. As you swallow a flap of tissue called the epiglottis seals off your windpipe, preventing the food from entering. After food enters the esophagus, contractions of the muscles push the food toward the stomach. These waves of muscles contractions are called peristalsis.

The Stomach – most mechanical digestion and some chemical digestion occur here. 1. Mechanical Digestion – 3 layers of muscle contract to produce a churning motion. 2. Chemical Digestion – occurs as the churning of food makes contact with digestive juices. a. digestive juices contains the enzyme pepsin, which chemically digests the proteins in food, breaking them down. Digestion in the Stomach (2 min.)

b. Digestive juice also contains hydrochloric acid, which helps pepsin work and also kills many bacteria that you swallow with your food. c. Stomach acid does not burn a hole in the stomach because cells produce a thick coating of mucus, which protects the stomach lining. Once food has been broken down in the stomach, it is now a thick liquid call chyme.

II. Final Digestion and Absorption takes place in the intestines. The Small Intestine- where most chemical digestion takes place. 1. It is about six meters long and 2-3 centimeters wide. 2. Almost all chemical digestion and absorption of nutrients takes place in the small intestine. 3. The liver and the pancreas deliver substances to the small intestine through small tubes called ducts. liver & pancreas (30 seconds)

4. The liver produces bile, a substance that breaks ups fat particles 4. The liver produces bile, a substance that breaks ups fat particles. Bile flows from the liver into the gallbladder, and organ that stores bile. Bile breaks up large fat particles into smaller fat droplets. 5. The pancreas produces enzymes that flow into the small intestine and help break down starches, proteins, and fats.

6. Villi are tiny finger-shaped structures that line the inside of the small intestine. The villi absorb nutrient molecules. These molecules are then passed into blood vessels and carried throughout the body for use by body cells. The Large Intestine – the last section of the digestive system. It is also called the colon. The 3 parts are ascending, transverse, and descending colon. 1. It is about 1.5 meters long. large intestine video (4-5 minutes)

2. It contains helpful bacteria that feed on the material passing through. They make certain vitamins, including vitamin K. 3. As material moves through the large intestine, water is absorbed into the bloodstream. The remaining material is readied for elimination from the body. 4. The large intestine ends in a short tube called the rectum. This is where the waste is stored. 5. Waste is then eliminated from the body through the anus, a muscular opening at the end of the rectum

Digestive System Disorders A. constipation: when too much water is absorbed into the large intestine B. diarrhea: condition when feces are too watery, caused by infection, nerves or stress C. stomachache: queasiness in stomach caused by problem in digestive process

Digestive Diseases: Ulcer definition: sores in the lining of the stomach or small intestine causes: bacterial infection or overuse of aspirin or ibuprofen symptoms: sharp, sudden constant stomach pain, bloated, loss of appetite, nausea, vomiting diagnosis: x-ray called a GI series, and a blood test treatment: antibiotics, acid-suppressing drugs to reduce acid & stomach protectors Video

Digestive Diseases: Colon Cancer definition: a cancer that develops in the tissues of the colon causes: a growth of the normal lining of the large intestine called a polyp symptoms: constipation, bloody stool, weight loss diagnosis: colonoscopy – using x-rays to take pictures of lining treatment: removal of tumor, chemotherapy Video

Digestive Diseases: Heartburn definition: stomach acid flowing back into esophagus causing a burning feeling causes: a condition called acid reflux where stomach valve doesn’t close properly symptoms: acids regurgitating, painful swallowing, chest pain, sore throat diagnosis: pH monitoring which records the amount acid backing up into the esophagus treatment: antacids, H2 blockers (Pepcid AC), avoid dairy products, coffee, pop, spicy foods Video

Digestive Diseases: Obesity definition: condition of excess fatness where more calories are consumed than burned off causes: oversized portions, lack of exercise, response to emotions (anger, stress, sadness) symptoms: can lead to high blood pressure, heart disease, diabetes, arthritis, cancers diagnosis: ideal weight table, body-fat test (see your doctor) treatment: appetite suppressants, fat blockers, diet, exercise stomach surgery (extreme) Video

Digestive Diseases: Diabetes definition: body cannot use sugar properly – extra sugar builds up in blood causes: pancreas does not produce insulin so extra sugar builds up in blood symptoms: thirsty, frequent urination, weak, hungry, weight loss, blurred vision diagnosis: urine test, blood test, plasma glucose test (to measure glucose levels in blood) treatment: insulin injections, insulin pump Video