SCIENCE

• Digestion


  The process of breaking down food for body absorption
• Two kinds of digestion

  • Mechanical digestion
  • Chemical digestion
• Mechanical digestion


  • Involves a physical process
• Chemical digestion


  • Relies on the powerful action of enzymes
• Enzymes


  Protein molecules that act as catalysts
• Catalysts


  Substances that help speed up chemical reactions
• Absorption


  Process by which nutrients obtained from food are transported to the body cells
• Two types of group organs

  • Digestive tract / alimentary canal
  • Accessory organs
• Digestive tract


  • Food passes directly through these organs
• Accessory organs


  • Organs that are not directly involved in digestion
• Mouth / Oral cavity


  First organ of digestion where food begins its travel
• Ingestion


  The process of receiving food into the mouth
• Lips


  • Have sensory receptors that can detect the texture and temperature of food
• Palate


  Mouth's upper boundary where food is pushed
• Saliva


  Contains several substances that are important in food processing
• Uvula


  A structure that dangles from the posterior area
• Teeth

  • Incisors (cutting and biting)
  • Canines (tearing)
  • Premolars (tearing and crushing)
  • Molars (grinding and crushing)
• A complete set of teeth number 32
• Bolus


  A ball-like mixture of food and saliva that forms in the mouth
• Pharynx


  Opening that leads to the esophagus and trachea
• Epiglottis


  Flap leaf-shaped cartilage that covers the opening of larynx
• Esophagus


  Long muscular tube where food travels from the mouth
• Peristalsis


  Series of wave-like contractions of the muscle in esophagus
• Stomach


  An expanded J-shaped organ
• Sphincters


  Prevents the backflow of food
• Cardiac sphincter


  Separates esophagus and stomach
• Pyloric sphincter


  Between stomach and small intestine
• Rugae


  Allows the stomach to stretch to store large meals
• HCl


  Softens meat
• Pepsin


  Protein digesting enzyme
• Chyme


  Thick semifluid mass of partially digested food
• Small intestine


  Longest part of digestive system and the final digestion takes place
• The small intestine is 20 feet long and 1 inch width
• Villi


  Tiny finger-like projections
• Duodenum


  Where chyme mixes with enzymes
• Jejunum


  Site of nutrient absorption
• Ileum


  Site of digestion
• Large intestine / Colon


  Final organ of digestive system
• The large intestine is 2.5 inches diameter and 5 feet length
• Parts of large intestine

  • Ascending colon
  • Transverse colon
  • Descending colon
  • Sigmoid colon