organisation

• Cells


  Basic building blocks of all living organisms
• Tissue


  Group of cells with similar structure and function
• Organ


  Group of tissues performing specific functions
• Organ system


  Group of organs performing a specific function
• Organism


  Collection of organ systems
• 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
• As temperature increases


  The rate of enzyme-controlled reactions increases
• At high temperatures


  Enzymes denature and the active site changes shape
• As pH changes from the optimum

  The rate of enzyme-controlled reactions decreases
• 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 into glycerol and fatty acids
• Protease enzymes


  Break down proteins into amino acids
• Amylase enzymes


  Break down starch into simple sugars
• Bile


  Produced by the liver, helps digest lipids by emulsifying them
• The iodine test turns blue-black in the presence of starch
• The biuret test turns lilac in the presence of proteins
• The lipid test forms a cloudy white emulsion in the presence of lipids
• The Benedict's test turns brick red in the presence of sugars
• Double circulatory system


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


  • Have a narrow lumen, thick muscle layer, and thick elastic tissue layer 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
• Red blood cells


  Contain hemoglobin which carries oxygen, have a biconcave shape to increase surface area
• Platelets


  Small cell fragments that help blood to clot
• Blood is considered a tissue made of plasma in which red and white blood cells and platelets are suspended
• Coronary arteries


  Blood vessels that supply the heart muscle with oxygen and glucose
• Blockage in coronary arteries

  Reduces blood flow and oxygen supply to heart muscle, can lead to heart attack
• Statins


  Drugs that slow down the buildup of fatty material in arteries
• Stent


  Surgical device placed in artery to keep it open and improve blood flow
• Faulty heart valves


  Can be stenotic (don't open fully) or regurgitant (leaky), reducing blood flow and oxygen supply