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
• 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 emulsifies fats, increasing the surface area for lipase enzymes to work
• The iodine test turns blue-black in the presence of starch
• The biuret test turns lilac in the presence of proteins
• The ethanol and water test forms a cloudy white emulsion in the presence of lipids
• The Benedict's test turns brick red in the presence of sugars after heating
• 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
  • Have thick muscle and elastic tissue layers to withstand high pressure
• Capillaries


  • Have very thin walls, only one cell thick, to allow 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 carries dissolved substances like glucose, amino acids, and hormones
• 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 to the heart muscle, can lead to heart attack
• Statins


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


  A device surgically placed in a narrowed artery to hold it open and improve blood flow