digestive system

• Digestive system


  Processes the breakdown and absorption of food and the removal of waste food products from the body
• Buccal cavity


  The mouth area, where food is chewed to break it down. Also known as the oral cavity.
• Salivary glands


  Produce saliva, which helps moisten food and make it easy to swallow
• Epiglottis


  A flap of cartilage behind the root of the tongue, which covers the opening of the windpipe when swallowing food
• Oesophagus


  A muscular tube that connects the throat with the stomach. Food moves down through the oesophagus to the stomach.
• Peristalsis


  A squeezing action by the muscles, helps the food move downwards to the stomach
• Stomach


  A sac (bag) with muscular walls that churn the food to break it up. It produces hydrochloric acid and enzymes to digest the food.
• Small intestine


  The duodenum. Here the food, partially digested by the stomach, now called chyme, is chemically altered by fluids from the liver and by bile from the pancreas. The duodenum is lined with villi, which are finger-like projections in the intestinal wall that increase the surface area and help the absorption of nutrients into the bloodstream.
• Large intestine or colon


  Reabsorbs fluids and processes waste products in preparation for elimination from the body
• Rectum


  The last part of the colon and links it to the anus. It stores faeces until they can be expelled from the body.
• Anus


  The opening in the body through which the faeces are expelled by the process of defecation. The anal sphincter muscle controls the opening and closing of the anus.
• Mechanical digestion


  When food is physically broken down to make it smaller
• Mechanical digestion


  1. Chewing action-the teeth break down large pieces of food into smaller ones that can be swallowed

  2. The stomach churns food to break it down

  3. In the small intestine the bile emulsifies (breaks into small particles) lipids, also known as fats, which helps with the mechanical digestion of fats
• Chemical digestion


  Where nutrients are broken down by enzymes to smaller molecules that can be absorbed into the blood and used by cells
• Chemical digestion


  1. In the buccal cavity, food is dissolved with saliva, which contains an enzyme called amylase

  2. The stomach mixes food with enzymes and hydrochloric acid while churning it

  3. Chemical digestion of proteins-broken down by pepsin in the stomach and small intestine
• Digestive process


  • Ingestion-food is taken into the body through the mouth
  • Digestion-physical and chemical breakdown of the food
  • Absorption-food passes through the intestine and into the bloodstream
  • Elimination-the undigested waste is removed from the body
• Digestive role of pancreatic juice

  • The pancreas produces digestive enzymes that are released into the small intestine
  • The pancreatic juices help the body to digest fats
  • The pancreatic juices are released into a system of ducts that culminate in the main pancreatic duct
• Digestive role of bile

  • Bile is a digestive juice produced by the liver
  • It helps the body absorb fat into the bloodstream
  • It is stored in the gallbladder until the body needs it to digest fats
  • It enters the small intestine through the bile duct
  • Bile emulsifies fats and neutralises stomach acid