the digestive system

• Parts of the digestive system:

  • Gastrointestinal (GI) Tract
  • Oesophagus
  • Stomach
  • Small intestine
  • Large intestine
  • Layers of GI tract wall:
  • Mucosa: Internal layer with structure varying based on functions
  • Submucosa: Dense layer of connective tissue with large blood vessels
  • Muscularis: Inner oblique layer, middle circular layer, and outer longitudinal layer
  • Serosa: Outer layer consisting of several layers of connective tissue
• Mechanical digestion:

  • Food is broken up into smaller pieces
  • Starts from chewing food (mastication) and mixing with saliva
  • Saliva helps to lubricate and contains salivary amylase
  • Continues in the stomach with smooth muscle contraction and mixes with digestive enzymes and acids
  • Can last for several hours
  • Rhythmic movement (peristalsis) of food along the whole GI, controlled by the autonomic nervous system
• Enzymes:

  • Chemical particles that help in digestion
• Hydrolysis:

  • Chemical reaction that breaks down large molecules into smaller molecules (proteins, lipids, and polysaccharides)
• Chemical digestion
• Absorption process:

  • Absorption and the products of absorption