human organisation

• Products


  Substances that are produced in a chemical reaction
• Reactants or substrates


  Substances that take place in a chemical reaction
• Enzyme


  A biological catalyst, speeds up the rate of a chemical reaction, made of protein
• Active site


  The part of an enzyme where the substrate attaches
• Lock and key theory

  Only one substrate is complementary (will fit into/is the same shape as) to the active site
• Complementary


  When two shapes fit together
• Amylase


  Breaks starch down into 'simple' sugars (maltose)
• The mouth

  Where salivary amylase is made
• The stomach, pancreas and small intestine.

  Where proteases are produced in the body
• Protease


  Break proteins down into amino acids
• In the pancreas and small intestine.

  Where lipase is produced
• Lipase


  Breaks lipids (fats) down into glycerol and fatty acid
• Small intestine


  Where nutrients are absorbed into the blood?
• Mechanical digestion


  Chewing in the mouth and churning in the stomach
• Chemical digestion


  Breakdown of large molecules by enzymes
• To convert food into small, soluble molecules that can be absorbed into the blood

  Why do we need to digest food?
• Stomach acid


  Kills pathogens and provides the optimum conditions for protease (pepsin) to work.
• pH 2


  The pH of the stomach
• Liver


  Where bile is made
• The gall bladder


  Where bile is stored and released from
• Neutralisation of stomach acid

  One function of bile when it mixes with stomach acid
• Emulsification


  One function of bile that increases the surface area of lipids to aid breakdown by lipase
• Slightly alkaline


  The pH of the small intestine
• Iodine solution


  Used to test for the presence of starch, turns from brown to blue/black
• Biuret reagent


  Used to test for proteins. Turns purple/lilac if proteins are present.
• Benedict's reagent


  Used to test for sugars. When heated, will turn from blue to brick red if sugars are present
• Trachea


  The wind pipe, leads from the mouth to the lungs

  
• Bronchi


  The trachea divides into two smaller tubes called bronchi

  
• Bronchioles


  The bronchi split into many smaller tubes called bronchioles

  
• Alveoli


  The small air sacs found at the end of the bronchioles
• Gas exchange


  The process that occurs in the alveoli
• Large surface area, excellent blood supply and very thin walls

  Three adaptations that alveoli have to increase the rate of gas exchange
• Maintains a steep concentration gradient

  A good blood supply around alveoli in the lungs and villi in the small intestine
• Diffusion


  The movement of particles from an area of high concentration to an area of low concentration
• Short diffusion pathway


  Walls of alveoli and capillaries are only one cell thick. Increases the rate of diffusion.
• Red blood cells


  Carry oxygen in the blood
• Haemoglobin


  A protein found in red blood cells that binds oxygen and also give these cells their distinct red colour.
• The heart


  The organ that pumps blood around the body
• A tissue


  A group of similar cells working together to perform a function
• An organ


  A group of different tissues working together to perform a function