The human digestive system

• why must food be digested?

  as the molecules are:

  • insoluble and too big to cross membranes and be absorbed into the blood
  • polymers, and must be converted to their monomers, so they can be rebuilt into molecules needed by body cells
• where does digestion and absorption occur?

  in the gut
• what is the structure of the gut?

  its a long, hollow, muscular tube
• what does the gut allow?

  it allows movement of its contents in 1 direction only
• how is each section of the gut different?

  each section is specialised and performs particular steps in the processes of mechanical and chemical digestion and absorption
• how is food propelled along the gut?

  by peristalsis
• what is peristalsis?

  rhythmic wave of coordinated muscular contraction in the circular and longitudinal muscle of the gut wall, passing food along the gut in 1 direction
• what is this an image of?

  peristalsis