digestive system

• roles of digestive system

  digestion and absorption
• digestion

  process of breaking down large food molecules into smaller molecules
• Absorption


  process of absorbing these small food molecules into the body
• How does chewing aid in digestion?

  It increases the surface area for enzymes to act on

  It make the food easier to swallow
• saliva


  The salivary glands in our mouth release saliva which lubricates the food and makes it easier to swallow.

  It also contains the enzyme amylase, which breaks down starch into maltose.
• What is the official name for the tube that carries food from the mouth to the stomach.

  oesophagus
• 3 roles of the stomach

  The stomach contracts its muscular walls to churn and mix the food.

  It produces pepsin, which is a type of protease enzyme, and breaks proteins down into amino acids.

  It produces hydrochloric acid, which a) provides the right pH for pepsin to function, and b) kills microorganisms.
• 2 roles of bile

  Bile is made by the liver, but it is stored in the gall bladder,

  After we have meal, it is released into the small intestine where it helps in two ways:

  One is to emulsify lipids, which means separate large droplets of lipid into smaller droplets.

  The other is to neutralise the acid from the stomach, which bile can do because it is alkaline
• Which enzymes does the pancreas produce?

  Amylase, proteases, and lipases
• Which enzymes does the small intestine produce?

  protease, amylase, lipase
• Give three ways in which villi are adapted for this role.

  There are many villi, which gives them a large total surface area over which to absorb nutrients

  They have a single layer of cells on their surface, which means nutrients only have to diffuse a short distance.

  They have a good blood supply which maintains a strong concentration gradient between the lumen and the blood
• What is the main role of the large intestine?

  Reabsorbs water and stores and eliminates undigested food
• role of small intestine

  -completes digestion and absorbs nutrients into the bloodstream
• where is bile made

  liver
• where is bile stored

  gall bladder
• what does bile do

  emulsifies fat and neutralises stomach acid