Digestive System PDF

3.3 The Digestive System What Happens When We Eat? What is the Digestive System? ► Organ system that takes in, breaks up, and digests it, then excretes the remaining waste ► Made up of a digestive tract and accessory organs The Digestive Tract ► Long...

3.3 The Digestive System What Happens When We Eat? What is the Digestive System? ► Organ system that takes in, breaks up, and digests it, then excretes the remaining waste ► Made up of a digestive tract and accessory organs The Digestive Tract ► Long tube with two openings that is composed of: Mouth ► Mouth ► Esophagus ► Stomach Esophagus ► Small Intestine Stomach ► Large Intestine Small intestine ► Rectum ► Anus Large intestine (colon) Anus Rectum The Digestive Tract ► Lined with epithelial tissue which is made up of many different types of cells ► Goblet cells secrete mucus ► Mucus protects against digestive enzymes and allows for a smooth passage along tube ► The digestive tube also includes layers of muscle tissues and nerves Accessory Organs ► NOT part of the digestive tract, but aid in digestion ► Liver ► Gallbladder ► Pancreas Digestive System Anus Mechanical vs. Chemical Digestion ► Mechanical Digestion: ► Physical breakdown of food ► Chemical Digestion: ► Break down of food using enzymes (biological catalysts) Mouth ► Begins the process of breaking down food ► Mechanical Digestion: ► Uses teeth and tongue ► Chemical Digestion: ► Chemicals called enzymes (in saliva) break apart food molecules Mouth: Saliva ► Provides water and enzymes (amylase) to chemically break down and moisten food ► Produced by epithelial tissue that lines the mouth and salivary glands  PERISTALSIS Esophagus ► Muscular tube connecting the mouth to the stomach of food ► Food moves through the esophagus involuntarily ► Muscles contract and relax WITHOUT conscious thought Peristalsis: ► Involuntary muscle contractions that move food through the esophagus Esophagus: Epiglottis ► A tiny flap-like structure Trachea ► Covers the trachea during swallowing to prevent food from entering the respiratory system Stomach ► Holds food and churns it (physical breakdown) to continue digestion ► Stomach lining produces digestive enzymes and acid (for chemical breakdown) as well as mucus ► Mucus protects stomach lining tissue from acid Small Intestine ► 6 m long and narrow ► Site of most digestion and absorption of nutrients ► Goblet cells in lining release mucus ► Nutrients diffuse through wall of the small intestine and enter the bloodstream ► Contains smooth muscles that contract and relax without conscious thought to move broken down food through Small Intestine: Villi ► Small intestines contain finger-like projections called villi ► Villi increase the surface area so there is more area for the absorption of nutrients Large Intestine (Colon) ► Only 1.5 m long and wider than small intestine ► Absorbs water from indigestible food ► Contains bacteria that assist in producing vitamins ► Remaining solid waste is excreted as feces from the anus Accessory Organ: Liver ► Produces bile ► Bile: fluid that helps to mechanically break down fats in food Accessory Organ: Gallbladder ► Stores bile produced by the liver Accessory Organ: Pancreas ► Releases enzymes into the small intestine that aid in digestion ► Produces insulin which helps regulate blood glucose levels Digestive System Diagram – Parts: Salivary glands Mouth Epiglottis Esophagus Liver Stomach Gallbladder Pancreas Large intestine Small intestine Rectum Anus Digestive System Problems Diabetes: ► Condition in which the pancreas produces too much or too little insulin hormone (regulates blood glucose (sugar) levels) ► Symptoms – weakness or dizziness due to too low/high blood glucose levels ► Type 1 (Juvenile) = treated with medication ► Type 2 (Adult-onset) = controlled by medication and diet Colitis: ► An inflammation of the lining of the large intestine ► Causes – viruses, bacteria, narrowed blood vessels, immune system failure ► Diagnosed using an endoscope and microscopic examination of tissue sample **When the Digestion Goes Wrong… ► Your body recognizes the presence of toxins produced by bacteria or spoiled food, as well as poisonous substances (including too much alcohol) ► Your digestive tract responds by attempting to remove them rapidly = vomiting or diarrhea Video: The Journey of the Digestive System HOMEWORK: ✔ Read pg. 80-82 in textbook; do Q: #2-4 (pg. 82) EXTRA HELP: ✔ Digestive System Review ANSWERS Q: # 2-4 (pg. 82) ► 2. Digestion is necessary because food must be broken down into molecules to be able to diffuse through the walls of the intestine into the bloodstream and ultimately diffuse into cells. ► 3. Substances added to the food in the digestive tract are saliva, stomach acid, enzymes, bile, and mucus. ► 4. Muscle tissue contracts to push food through the digestive system.