Organisation

• organ systems

  1. cells
  2. tissues
  3. organs
  4. organ systems
• what is a tissue


  a group of specialised cells that work together to carry out a particlular function
• Examples of tissues

  • muscular tissues - contracts to move whatever its attched to
  • glandular tissues - makes and seretes chemicals like enzymes and hormones
  • epithelial tissue- covers some parts of the body e.g inside the gut
• what is an organ 


  a group of tissues that work together to perform a certain functions
• the tissues that make up the stomach 


  • muscular - moves the stomach wall to churn up the food
  • glandular - makes digestive juices to digest food
  • epithelial - covers the outside and inside of the stomach
• what is an organ system 


  a group of organs working together to perform a particular function
• the digestive system organs :


  • glands (e.g. pancreas and the salivary glands) which produce digestive juices
  • stomach and small intesine- digest food
  • liver - produces bile
  • small intestine - absorbs soluable food molecules
  • large intestine - absorbs water from undigested food
• what is an enzyme 


  a biological catalyst
• a catalyst is a substance which speeds up the rate of reaction without being chnaged or used up in a reaction
• enzymes are all large protiens and all protiens are made up of chains of amino acids
• how enzymes work (lock and key explained)


  • every enzyme has an active with a unique shape that fits onto the substance involved in a reaction
  • enzymes usually only catalyse one specific reaction
  • for an enzyme to work the substrate has to fit onto its active site, if the substrate doesnt match the enzymes active site then the reaction wont be catalysed
• how temperature affects enzymes 


  • changing the temp changes the rate of an enzyme-catalysed reaction
  • a higher temp increases rate at first
  • if it gets too hot the bonds holding the enzyme together break
  • this changes the shape of the active site so the substrate no longer fits - enzyme has denatured
• how pH effects enzymes 


  • all enzymes have an optimum ph that they work best a (it is often neutral pH 7)
  • if pH is too high or low if affects the bonds holding the enzyme together which denatures the enzyme
• why are digestive enzymes needed? 


  to break down big molecules (starch, protiens and fats) into smaller soluable molecules that can be absorbed into the blood stream
• Carbohydrases break down carbohydrates into simple sugars
• amylase is an example of a carbohydrase and it breaks down starch
• where is amylase made in the body ?


  Salivary glands

  Pancreas

  Small intestine
• Proteases convert proteins into amino acids
• where are proteases made in the body ?


  • the stomach (its called pepsin there )
  • the pancreas
  • the small intestine
• lipases convert lipids into glycerol and fatty acids
• lipids are fats and oils
• where are liapases made in the body ?


  • the pancreas
  • the small intestine
• where is bile produced ?


  in the liver, it is stored in the gall bladder before its released into the small instestine
• the 2 uses of bile :

  • neutralises the hydrochloric acid from the stomach, this allows the enzymes in the small intestines to be more efficient as they wor best in alkaline conditions
  • emulsifies fats (breaks the fats into tiny droplets)- this gives a much bigger surface area for the liapase to work on making digestion go faster
• enzymes in the digestive system are produced by speicalised cells in the gut lining and in glands
• salivary glands 


  • produce amylase enzyme in the saliva
• Liver 


  • where bile is produced
  • bile neutralises stomach acid and emulsifies fats
• gall bladder 


  • where bile is stored before it is released into the small intestines
• pancreas


  produces protease, amylase and lipase enzymes and releases these into the small intestine
• large intestine 


  where excess water is absorbed from food
• small intestine

  • produces protease, amylase and lipase enzymes to complete digestion
  • also where the digested food is absorbed out of the digestive system into the blood
• what is a risk factor ?


  something that is linked to an increase in the likeleyhood that a person will develop a certain disease in their lifetime (they do not guarantee someone getting the disease)
• risk factors for heart disease include smoking, high cholesterol levels, being overweight or obese, lack of exercise, drinking too much alcohol
• high cholesterol levels cause heart disease because they are part of the build up of fatty deposits on the inside of arteries which leads to them becoming blocked and reducing the flow of blood to the heart muscle
• many non comunicable diseases are caused by several risk factors interacting with each other rather that 1 factor alone
• risk factors that can cause a disease directly 


  • smoking
  • obesity
  • drinking too much alcohol
  • exposure to radiation
• smoking :


  • proven to directly csause cardiovascular disease, lung disease and lung cancer
  • ot damages the walls of arteries and the cells in the lining of the lungs
• non comunicable dieases can be costly ...

  • human cost - 10s of millions of people die around the world from these diseases each year, people with these diseases may have a lower quality of life and a shorter lifespan which can effect not only themselves but loved ones too
  • financial cost - the cost to the NHS of researching and treating these diseases is huge. families may also have to move their homes or adapt their homes to help a fmily member with the diease which can be costly
• the main causes of death worldwide are non communicable diseases such as heart disease, stroke, diabetes and some types of cancer
• what are communicable diseases


  diseases that can be spread from person to person or between aniamls and people. they can be caused by things like bacteria, viruses, viruses and parasites and fungi