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

  Substrate molecule (key) fits into the active site (lock) 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 excessive temperatures

  The enzyme denatures and the active site changes shape
• As pH increases/decreases from the optimum

  The rate of enzyme-controlled reactions decreases
• Different enzymes have different optimum pHs
• Digestive system

  Organ system where several organs work together to digest and absorb food
• 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
• Locations of enzyme production

  • Mouth (amylase)
  • Stomach (protease)
  • Pancreas (all 4 enzymes)
  • Small intestine (all 4 enzymes)
• Iodine test

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

  Tests for the presence of proteins (lilac colour change)
• 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)
• Double circulatory system

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

  • Left atrium
  • Left ventricle
  • Right ventricle
  • Right atrium
  • Pacemaker
• Arteries

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

  Have very thin walls (only 1 cell thick) to allow for short diffusion distance
• 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
• 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

  Supply the heart muscle with oxygen and glucose
• Fatty material narrows coronary arteries

  Reduces blood flow and oxygen to the heart muscle