organisation

• Tissue


  One type of cell carrying out one function
• Organ


  Made up from lots of different types of cells carrying out a joint function
• Organ system


  A group of organs that work together to carry out a function
• Hierarchy of biological organisation

  • Cells
  • Tissues
  • Organs
  • Organ systems
• Digestive system


  1. Mouth mechanically breaks down food

  2. Saliva glands produce enzymes

  3. Liver produces bile to emulsify fats

  4. Small intestine absorbs glucose, ions

  5. Stomach churns food, provides acidic environment

  6. Pancreas produces enzymes

  7. Large intestine removes excess water

  8. Rectum and anus remove waste
• Digestive enzymes


  • Lipase
  • Protease
  • Amylase
• Lipase


  Breaks down fats into fatty acids and glycerol, made in pancreas and small intestine, works in small intestine
• Protease


  Breaks down proteins into amino acids, made in stomach, pancreas and small intestine, works in stomach and small intestine
• Amylase


  Breaks down starch into sugars, made in saliva glands, pancreas and small intestine, works in mouth and small intestine
• Enzyme mechanism


  • Enzyme has specifically shaped active site
  • Substrate binds to active site
  • Enzyme facilitates transition state
  • Catalysis occurs
  • Products are released, enzyme unchanged
• Temperature increases


  Enzyme activity increases
• Temperature is very low or very high


  Enzyme becomes denatured
• pH is too high or too low


  Enzyme becomes denatured
• Respiratory system


  Air goes in through mouth/nose, down trachea, into bronchi, bronchioles, alveoli for gas exchange, diaphragm and intercostal muscles move to bring air in and out
• Cardiovascular system


  Double circulatory system, blood pumped from heart to lungs and back, then to rest of body
• Path of blood flow

  • Vena cava
  • Right atrium
  • Right ventricle
  • Pulmonary artery
  • Lungs
  • Pulmonary vein
  • Left atrium
  • Left ventricle
  • Aorta
• Heart


  • Valves only allow one-way flow
  • Left side has thicker muscle to pump blood further
• Blood vessel types


  • Arteries (oxygenated blood, thick walls, thin lumen)
  • Capillaries (one cell thick, large surface area)
  • Veins (deoxygenated blood, thin walls, thick lumen, valves)
• Blood components


  • Red blood cells (no nucleus, carry oxygen)
  • White blood cells (immune system)
  • Platelets (clotting)
• Fatty deposits build up in coronary arteries

  Can lead to blood clots and heart attacks
• Risk factors for cardiovascular disease

  • Smoking
  • High blood pressure
  • High salt/fat diet
• Health


  Overall state of physical and mental well-being, affected by diet, exercise, community, genes
• Epidemiology


  Studies looking at levels of health and illness in a population, to identify risk factors
• Cancer


  Uncontrolled cell division leading to malignant tumours that can spread, unlike benign tumours
• Risk factors for cancer

  • Smoking
  • Poor diet
  • Sun exposure
  • Unprotected sex
• Leaf structure


  Epidermis, waxy cuticle, palisade mesophyll (photosynthesis), spongy mesophyll (gas exchange), stomata, xylem (water transport), phloem (food transport)
• Factors affecting transpiration rate

  • Light intensity
  • Temperature
  • Wind
  • Humidity