Organisation

• a tissue is a group of cells working together to perform a shared functions
• an organ is a group of tissues working together to perform a shared function
• an organ system is a group of organs with related functions working together to perform certain functions
• a catalyst is a substance which increases the rate of reaction, without being changed or used up
• an enzyme is a biological catalyst
• enzymes have specific shapes that fit to specific substrates in order to speed up reactions, if their environment is changed the enzymes can become denatured (change shape)
• carbohydrase convert Carbohydrates into simple sugars
• Protease converts Proteins into Amino Acids
• Lipase converts Lipids into Glycerol and fatty acids
• Bile neutralises the stomach acid and emulsifies fats, its produced in the liver but stored in the gall bladder
• the Salivary glands produce Amylase
• the pancreas produces protease, amylase and lipase enzymes - and releases these into the small intestine
• the stomach produces protease called pepsin
• the stomach produces Hydrochloric acid for two reasons -

  • to kill bacteria
  • to give the right pH for the protease enzyme to work (pH 2)
• the large intestine is where excess water is absorbed from the food
• the test for sugars is Benedict's solution
• the test for starch is Iodine solution
• the test for protein is Biuret solution
• the test for lipids is Sudan iii
• the air you breathe in through the trachea splits into two tubes called Bronchi, one going into each lung
• the bronchi split into smaller tubes called bronchioles, which end up in the alveoli
• flow of blood in the right side heart -

  • blood flows into the atrium through the Vena Carva
  • the atrium contracts and pushed blood into the ventricles
  • the ventricles contract, forcing blood into the pulmonary artery, and out of the heart
• flow of blood in the left side of the heart -

  • blood flows into the atrium through the pulmonary vein
  • the atrium contracts, forcing the blood into the ventricles
  • the ventricles contract, forcing blood into the aorta and out of the heart
• the heart has a pacemaker which is located in the right atrium, it produces a small electrical impulse which allows the heart to contract
• arteries carry blood away from the heart
• capillaries are involved in the exchange of materials at the tissues
• veins carry blood to the heart
• Arteries -

  • walls are strong and elastic so they can handle high pressure blood
  • walls are thick compared to the lumen in the middle
  • contain layers of muscle to make them strong, and elastic fibres to allow them to stretch
• Capillaries -

  • arteries branch into capillaries
  • they carry blood very close to each cell in the body to exchange substances with them
  • they have permeable walls
  • walls are only one cell thick - decreasing diffusion distance
• Veins -

  • capillaries form up to join veins
  • walls aren't as thick as arteries
  • larger lumen to help blood flow
  • have valves to keep blood flowing in the right direction
• valves prevent the backflow of blood
• Red blood cells -

  • carry Oxygen
  • biconcave disc shape
  • don't have a nucleus
  • contain a red pigment called Haemoglobin
• white blood cells -

  • engulf unwelcome pathogens - Phagocytosis
  • produce antibodies to neutralise toxins
  • they do have a nucleus
• Platelets -

  • small fragments of cells with no nucleus
  • help the blood clot at a wound
• Plasma -

  • carries everything in the blood : red and white blood cells, glucose, hormones, proteins etc
• Coronary heart disease is when the coronary arteries that supply the blood to the muscle of the heart get blocked up by a build up of fatty materials. This causes the arteries to become narrow, which restricts the blood supply and can cause a heart attack
• stents are tubes that are inserted inside arteries to keep them open and ensure that blood can pass through - this keeps the heart beating and the person alive.
• statins reduce the cholesterol in the blood and reduce the risk of heart attacks
• advantages of statins -

  • reduce amount of strokes and heart attacks
  • can increase the amount of beneficial type of cholesterol
• disadvantages of statins -

  • long term drug that must be taken regularly
  • can cause side effects such as headaches or even kidney failure