the digestive system

• Parts of the digestive system include:

  • Oesophagus
  • Stomach
  • Small intestine
  • Large intestine
• Layers of the 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 involves breaking up food into smaller pieces

  • Process starts from chewing food (mastication) and mixing with saliva
  • Saliva helps to lubricate and contains salivary amylase
  • Mechanical digestion 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 tract, controlled by the autonomic nervous system
• Enzymes are chemical particles that aid in digestion

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

  • Absorption involves the uptake of nutrients from the digestive system into the bloodstream
  • Products of absorption include various nutrients such as proteins, lipids, and polysaccharides