digestive system INTRODUCTION DIGESTIVE SYSTEM ORGANS THE ACCESSORY ORGANS IN DIGESTION скачать в хорошем качестве

digestive system INTRODUCTION DIGESTIVE SYSTEM ORGANS THE ACCESSORY ORGANS IN DIGESTION

The activities of the digestive system can be grouped under 6 main headings: 1. INGESTION: This process involves taking foods and liquids into the mouth (eating/drinking). 2. SECRETION: Each day, cells within the walls of the GI tract, accessory digestive organs secrete a total of about 7 liters of water, acid, buffers, and enzymes into the lumen (interior space) of the tract. LECTURE GIT THE DIGESTIVE SYSTEM PROCESSES 3. MIXING AND PROPULSION: Alternating contractions and relaxations of smooth muscle in the walls of the GI tract mix food and secretions and propel them toward the anus. This capability of the GI tract to mix and move material along its length is called motility. 4. DIGESTION: This consist of: • Mechanical breakdown of food by, e.g. Mastication (chewing) • Chemical digestion of food into small molecules by enzymes present in secretions produced by glands and accessory organs of the digestive system. LECTURE GIT THE DIGESTIVE SYSTEM PROCESSES 5. ABSORPTION: This is the process by which digested food substances pass through the walls of some organs of the alimentary canal into the blood and lymph capillaries for circulation and use by body cells. 5. DEFECATION: This is the process by which digested food substances pass through the walls of some organs of the alimentary canal into the blood and lymph capillaries for circulation and use by body cells THE ACCESSORY ORGANS IN DIGESTION ▶ The accessory digestive organs include: • The teeth, • Tongue, • Salivary glands, • Liver, • Gallbladder, and • Pancreas. ▶ Teeth aid in the physical breakdown of food, and the tongue assists in chewing and swallowing. ▶ The other accessory digestive organs, however, never come into direct contact with food. They produce or store secretions that flow into the GI tract through ducts; the secretions aid in the chemical breakdown of food.