Science WK1

• Digestive system


  Breaks down the food we eat both physically and chemically, one step at a time
• Physical digestion


  Smashing the food into a mush
• Chemical digestion


  Bathing the mushed food into enzymes as much as possible
• Digestion occurs only when it becomes more chemical than mechanical
• Parts and function of the digestive system

  1. Ingestion

  2. Digestion

  3. Absorption

  4. Defecation

  
• Ingestion


  The process of introducing the food into our body, also known as eating
• Ingestion


  • Mechanical and chemical process
  • Chewing to pulverize the food
  • Salivary glands release enzymes (amylase)
• Bolus


  The chewed food
• Propulsion


  The mechanism of swallowing the food, a voluntary movement
• Peristalsis


  A process by which the smooth muscles of the walls of your digestive organs take turns into contracting and relaxing to squeeze food through the lumen or cavity in your alimentary tract (gastrointestinal tract)

  
• Mechanical digestion in the stomach

  • Gastric acid further breaks the food down
  • Stomach churns the food and mixes it with stomach secretions
• Chyme


  A semifluid acidic mixture
• Chemical digestion


  The liver, gallbladder and the pancreas releases more enzymes into the alimentary canal to further break the food into its most basic form
• Absorption


  Taking in nutrients by cells, the goal of the whole process
• Defecation


  Removing any leftover wastes after the nutrients have been absorbed
• Stages of food processing

  1. Ingestion

  2. Digestion

  3. Absorption

  4. Defecation

  
• Digestive system


  Works with the circulatory, respiratory, and excretory systems in providing the body with nutrients for energy

  
• The structure of the small intestine is designed for absorption of nutrients

  
• The inside of the small intestine is lined with villi that absorb nutrients from the liquid mixture called chyme produced in the stomach from the food we eat