b2

• 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 (key) fits into the active site (lock) 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
• Denaturation

  When the shape of the enzyme's active site is permanently changed, causing it to stop working
• Optimum pH

  The pH at which an enzyme works at its fastest rate
• Parts of the digestive system

  • 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 - blue-black colour indicates presence of starch
• Biuret test - lilac colour indicates presence of protein
• Ethanol and water test - cloudy white emulsion indicates presence of lipids
• Benedict's test - colour change to brick red indicates presence of sugars
• 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 by sending regular electrical impulses
• Arteries


  • Have a narrow lumen
  • Have thick muscle and elastic tissue walls 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
• 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