Transcript Digestive System
Digestive System Knife Food Processor Garbage Disposal Which organ of the digestive system does each picture represent? • The function of the digestive system is to break down food so that it can be used as energy in your body. • The system consists of a series of complex organs and glands (which excrete enzymes) that break down food into small usable particles. Mechanical Digestion: -food is broken down mechanically, with movement Ex: Teeth Chemical Digestion: -food is broken down with a chemical or enzyme Ex: Saliva • Peristalsis- series of involuntary smooth muscle contractions along the walls of the digestive tract. • Moves food through the digestive system. Organs Involved: 1. Mouth 2. Esophagus (A) 3. Stomach (C) 4. Small Intestine (E) 5. Large Intestine (F) • • • • Appendix Pancreas (D) Liver (K) Gall Bladder (J) Digestion begins in the mouth. As you chew your food, two processes are occurring: 1. TEETH- your teeth begin mechanical digestion by breaking down food into smaller pieces. 2. SALIVA- this enzyme helps break down starches chemically 1 The mouth completes both mechanical and chemical digestion! As you swallow, the food must pass several structures: • Pharynx- Back of the throat opens into esophagus • Epiglottis- flap of tissue that keeps chewed food from going down the trachea to the lungs. As you swallow, the epiglottis flops closed. • Larynx- Vocal cords • The esophagus is a long tube that runs from the mouth to the stomach. • After being chewed and swallowed, the food ball (bolus) enters the esophagus. 2 • The food is deposited in the Stomach. • The stomach is a large, sac-like organ made of muscle. 3 • The stomach churns food AND bathes it in gastric juice (acidic). • Food remains in the stomach for 2-4 hours, turning into a thin liquid soup called chyme. 3 The stomach completes both mechanical and chemical digestion! • The liquid chyme is the transported to the small intestine. • SI is a narrow muscular tube about 6 meters long, lined with villi. 4 • Bile and other enzymes are injected into the Small Intestine to further break down the food. Is this mechanical or chemical digestion? 4 Food remains in the SI for 3-5 hours Don’t forget the Bacteria! • Villi- finger-like extensions that absorb nutrients • Villus expand surface area of SI. 4 • The function of the SI is to absorb all usable nutrients. • The villi are covered with capillaries which pick up the nutrients for ALL cells in the body. 4 What system works with Digestive? Blood vessels pick up nutrients from SI • Anything (liquid or solid) that is not absorbed by the SI is sent to the Large Intestine. • The colon absorbs most excess liquids. 5 Don’t forget the Bacteria! • After about 18-24 hours… • The END process- solid waste (feces) is stored in the rectum until it is excreted through the anus. 5 • The digestive system is also part of the Excretory system! Your meal’s entire journey through the Digestive System has taken between 24 and 33 hours. Many organs play a role in the digestion of foods but never come in contact with food, we call these accessory organs. Three such organs are: – Liver – Gall Bladder – Pancreas • Liver- large organ located above and in front of the stomach. • It filters toxins from the blood and makes bile (breaks down fats). • Gall Bladder- small, sac-like organ located near the SI. • It stores and releases bile into the small intestine. • Pancreas- an enzyme producing organ located below the stomach and above the intestines. • Enzymes from the pancreas aid in digestion of carbohydrates, fats and proteins in the small intestine.