THE DIGESTIVE SYSTEM

• Digestive system


  • Comprised of ten organs covering nine meters
  • Contains over 20 specialized cell types
  • One of the most diverse and complicated systems in the human body
  • Its parts continuously work in unison to transform the raw materials of food into the nutrients and energy that keep you alive
• Main components of the digestive system

  • Gastrointestinal tract
  • Pancreas, gallbladder, and liver
  • Body's enzymes, hormones, nerves, and blood
  • Mesentery
• Digestive process


  1. Anticipation of food triggers saliva production

  2. Chewing and saliva turn food into a moist lump called the bolus

  3. Peristalsis propels the bolus down the esophagus into the stomach

  4. Stomach walls break down the bolus into chunks

  5. Stomach acids and enzymes start to dissolve the food

  6. Bile, pancreatic and intestinal juices break down fats, proteins and carbohydrates in the small intestine

  7. Nutrients are absorbed through the villi in the small intestine

  8. Leftover fiber, water and dead cells make it to the large intestine where most fluid is drained out

  9. Remaining waste is expelled through the anus
• Gastrointestinal tract


  A twisting channel that transports food and has an internal surface area of between 30 and 40 square meters
• Peristalsis


  A series of defined muscular contractions that propel food down the esophagus
• Chyme


  The frothy liquid that the bolus becomes after 3 hours in the stomach
• Villi


  Millions of tiny projections in the small intestine that create a huge surface area to maximize absorption of molecules
• Stool


  The soft mass of leftover fiber, water and dead cells that is expelled through the anus
• what do glands do?

  produce the digestive juices containing enzymes which break down food
• what does the stomach produce?

  hydrochloric acid which kills bacteria and provides the optimum ph for the protease enzyme to work
• what happens at the small intestine?

  soluble molecules are absorbed into the blood
• what does the liver produce?

  bile
• where is bile stored?

  in the gall bladder
• where is bile stored?

  in the gall bladder
• what does bile do?

  help the digestion of lipids
• what does the large intestine do?

  absorbs water from undigested food to produce faeces
• what happens to the faeces?

  passed out of body through rectum and anus