digestion

• digestive enzymes break down...

  big molecules
• starch, proteins and fats are...

  big molecules which need to be broken down because they are too big to pass through the walls of the digestive system
• ... breaks down carbohydrates

  carbohydrase
• carbohydrates are broken down into...

  simple sugars
• carbohydrase is produced in...

  - salivary glands

  - pancreas

  - small intestine
• what type of enzyme is amylase?

  carbohydrase found in the salivary glands and pancreas
• what does amylase break down?

  Starch into maltose (sugars)
• ... breaks down proteins

  protease
• proteins are broken down into...

  amino acids
• protease is produced in...

  - stomach

  - pancreas

  - small intestine
• what type of enzyme is pepsin?

  protease found in the stomach
• what does pepsin break down?

  proteins into smaller peptides and amino acids
• ... breaks down lipids

  lipase
• lipids are broken down into...

  fatty acids and glycerol
• lipase is produced in...

  - pancreas

  - stomach
• ... neutralises stomach acid and emulsifies fats

  bile
• what does bile do?

  - helps speed up digestion of lipids (emulsifies)

  - neutralises HCl so that pH is optimum for enzymes
• where is bile produced?

  in the liver
• where is bile stored?

  in the gallbladder
• where is bile released?

  in the small intestine
• is bile acidic or alkaline?

  alkaline (pH of around 8)
• how does bile neutralise stomach acid?

  the hydrochloric acid in the stomach makes the pH too acidic for enzymes in the small intestine to work properly. bile is alkaline, so it neutralises the acid and makes the conditions alkaline. the enzymes in the small intestine work best in these alkaline conditions
• what does it mean when fats are emulsified?

  emulsification is the process by which large lipids are broken into tiny lipid droplets - emulsification increases the surface area of lipids, which helps to speed up the activity of lipase
• HCl (hydrochloric acid) is made in...


  the stomach
• what does HCl do?

  - creates optimum pH for pepsin in the stomach

  - kills bacteria

  - helps break down food molecules
• is HCl acidic or alkaline?

  acidic (pH of around 2)
• digestion


  the process of mechanically and enzymatically breaking down food into substances for absorption into the bloodstream
• digestion system


  organ system that breaks down the food into simple substances
• mouth


  begins the digestion of carbohydrates with the amylase enzyme in the saliva
• oesophagus


  muscular tube which moves ingested food to the stomach
• liver


  where bile is produces which neutralises stomach acid and emulsifies fats
• stomach


  muscular and elastic sac that serves mainly to store food, break it up mechanically, and begin chemical digestion of proteins and fat with pepsin. it produces hydrochloric acid to kill bacteria and give the optimum pH for pepsins to work in (pH of around 2)
• gallbladder


  where bile is stored before it's released into the small intestine
• pancreas


  produces protease, carbohydrase and lipase enzymes and releases them unto the small intestine
• large intestine


  receives food from the small intestine. this is where water and electrolytes and absorbed and undigested food is gotten rid of
• small intestine


  receives food from the stomach. this is where most chemical digestion and nutrient absorption of food takes place
• rectum


  where faeces (made up of mainly indigestible food) are stored before being excreted through the anus
• food tests

  required practical that show the presence of various biological molecules in samples or structures.
• what is used to detect sugar?

  benedict's solution
• benedict's solution is...


  blue