Organisation

• Cells are the basic building blocks of all living organisms
• Tissue


  A group of cells with similar structure and function
• Organ


  A group of tissues performing specific functions
• Organ system


  A group of organs performing a specific function
• Organism


  A group of organ systems together
• Enzymes


  Protein molecules found in cells that speed up reactions in the body
• Enzymes


  • They can be reused as their shape remains unchanged
  • They depend on their shape to work
• Lock and key model


  Explains how enzymes work - the substrate molecule fits into the active site of the enzyme
• Metabolism


  Reactions that build up and break down molecules, controlled by enzymes
• Optimum temperature


  The temperature at which an enzyme works at its fastest rate
• Optimum pH


  The pH at which an enzyme works at its fastest rate
• Digestive system organs

  • Mouth
  • Esophagus
  • Stomach
  • Pancreas
  • Small intestine
  • Large intestine
  • Rectum
  • Anus
  • Liver
  • Gallbladder
• Carbohydrase enzymes


  Break down carbohydrates into simple sugars
• Lipase enzymes


  Break down lipids (fats) into glycerol and fatty acids
• Amylase enzymes

  Break down starch into simple sugars
• Protease enzymes


  Break down proteins into amino acids
• Bile


  Produced by the liver, helps digest lipids by emulsifying them
• Iodine test


  Tests for the presence of starch (blue-black colour)
• Biuret test

  Tests for the presence of proteins (lilac colour)
• Lipid test


  Tests for the presence of lipids (cloudy white emulsion)
• Benedict's test

  Tests for the presence of sugars (colour change to brick red)
• Aorta


  Major blood vessel carrying oxygenated blood from the heart to the body
• Vena cava


  Major blood vessel carrying deoxygenated blood from the body to the heart
• Pulmonary artery


  Carries deoxygenated blood from the heart to the lungs
• Pulmonary vein

  Carries oxygenated blood from the lungs to the heart
• Heart valves

  Prevent the backflow of blood
• Double circulatory system


  Blood is pumped to the body by the left side of the heart and to the lungs by the right side
• Trachea


  The windpipe
• Bronchi


  The smaller tubes branching off from the trachea
• Alveoli


  The tiny air sacs in the lungs where gas exchange occurs
• Pacemaker


  Controls the resting heart rate and sends regular impulses to the heart
• Arteries


  Have a narrow lumen, thick muscle and elastic tissue layers to withstand high pressure
• Capillaries


  Have very thin walls, only one cell thick, to allow for short diffusion distances
• Lumen


  The part inside where the blood is carried
• Arteries


  • Narrow lumen
  • Thick layer of muscle around the artery that can contract to pump blood
  • Thick elastic tissue layer that recoils and maintains pressure
• Capillaries


  The smallest blood vessels
• Capillaries


  • Very thin walls, only one cell thick
  • Allow for short diffusion distance for gas exchange
  • Very narrow, so red blood cells travel in single line
  • Many capillaries provide large surface area for gas exchange
• Veins


  • Larger lumen compared to arteries
  • Thinner walls made of elastic and muscle tissue
  • Have valves to prevent backflow of blood
• Components of blood


  • Plasma
  • White blood cells
  • Red blood cells
  • Platelets
• Plasma


  The liquid part of blood that transports dissolved substances