Organisation

• Muscle cells:

  • Can contract (get shorter)
  • Contain special protein fibres which can change their length
  • packed full of mitochondria to provide energy for contraction
  • muscle cells work together to for, muscle tissue
• What is a tissue?

  A tissue is a group of simillar cells that work together to carry out a function .
• What is an organ?

  An organ is a group of tissues working together to perform a specific function.(example is the stomach)

  • the stomach contains muscle tissue and glandular tissue (which releases enzymes)
• What is an Organ system

  • an organ system is a group of organs working together to perform a function
• Give an example of an organ system

  • Digestive system
  • circulatory system
  • respiratory system
• What are the 3 main nutrients food contain?

  • carbohydrates (e.g.starch)
  • protein
  • lipids(fats)
• Carbohydrates, protein and lipids

  • All of these are large molecules
  • to big to be absorbed into the bloodstream
  • so they ave to be digested
• Digestion

  • During digestion, large food molecules are broken down into small molecules By enzymes.
  • The small molecules can then be absorbed into the bloodstream.
• Human digestive system: function of salivary gland(mouth)

  1.mouth-food is chewed by the teeth and mixed with saliva to produce a bolus, the saliva produces amylase enzymes .

  
• Human digestive system :function of Oesophagus 2.oesophagus-A tube from the mouth to the stomach

  
• 3.Human digestive system: stomach

  • Stomach- digests food
  • produces protease enzyme (pepsin)
  • Also produces HCl to kill bacteria

  
• 4.Human digestive system: small intestine

  Produces protease, lipase and amylase

  . Small food molecules produced by digestion are absorbed into the blood stream either by diffusion or active transport.
• 5.Human digestive system:pancreas


  Produces protease amylase and lipase
• 6.Human digestive system:large intestine 


  Water is absorbed from food
• 7.Human digestive system:anus

  Waste leave the body
• 8. Human digestive system:liver


  Produces bile to neutralise stomach acid and emulsify fats
• 9.Human digestive system:gall bladder


  Stores bile before it’s released into small intestine
• Enzyme

  • enzyme is a catalyst (speeds up) chemical reactions
  • Enzymes are large protein molecules and they have a groove on the surface called an active site.
  • The active site is where the substrate attaches to
• Carbohydrates

  • starch is a carbohyrate
  • amylase is made in the salivary glands, pancreas and small intestine.

  the enzyme amylase breaks down starch into sugar
• Protease

  • Protease are made in the stomach pancreas and small Intestine

  the enzyme protease breaks down proteins into amino acids
• Lipases

  • Lipase are made in the pancreas and small intestine

  the enzyme lipase breaks down lipids into glycerol and fatty acids
• Bile

  • bile neutralises stomach acids and emulsifies fats(breaks down the fats into tiny droplets)
  • Bile is produced in the liver
  • bile is stored in the gall bladder before it’s released into the small intestine
  • bile helps to speed the digestion of lipids
• Digestive enzymes

  • Starch proteins and fats are big molecules
  • they’re too big to pass through the wallsmof the digestive system
  • so digestive enzymes break these big molecules into smaller ones
  • this makes it easier to be absorbed into the blood stream
• Humans have a double circulatory system

  • The circulatory system is made up of the heart, blood vessels and blood.
  • a double circulatory system is two circuits joined together
  • in the first circuit: the heart pumps deoxygenated blood (blood without oxygen)to the lungs.the blood picks up oxygen at the lungs
  • Oxygenated blood (blood with oxygen)then return to the heart.
  • In the second circuit: the heart pumps oxygenated blood around all the other organs of the body. This delivers oxygen to the body cells.
  • deoxygenated blood returns to the heart to be pumped out to the lungs again.
• Arteries

  • arteries carry blood away from the heart
  • the heart pumps the blood out at high pressure
  • so artery walls are strong and elastic
  • thick layers of muscle to make them strong
  • have elastic fibres to allow them to stretch and spring back
• Capillaries

  • arteries branch into capillaries
  • capillaries are really tiny
  • they have gaps in their walls, so substances can diffuse in and out
  • supply food and oxygen. And takeaway waste like C02
• Veins

  • Capillaries join up to form veins
  • the blood is at lower pressure in the veins, meaning the walls don’t need to be as thick as artery walls. Veins have a bigger lumen than artery
  • veins have valves