Organisation

• Cells


  Make up all living things
• Tissue


  A group of specialised cells with a similar structure and function. They can be made of more than one type of cell
• Tissue examples


  • Muscular tissue
  • Epithelial tissue
• Organs


  Formed from a number of different tissues, working together to produce a specific function
• Organ example


  • Stomach
• Organ systems


  Organs organised to work together to perform a certain function
• Organ system example


  • Digestive system
• Organs in the digestive system

  • Glands (salivary glands and pancreas)
  • Stomach
  • Small intestine
  • Liver
  • Gall bladder
  • Large intestine
  • Rectum
  • Anus
• Enzymes


  Biological catalysts (a substance that increases the rate of reaction without being used up)
• Enzymes


  • They can both break up large molecules and join small ones
  • They are protein molecules and the shape of the enzyme is vital to its function
  • Each enzyme has its own uniquely shaped active site where the substrate binds
• Lock and Key Hypothesis

  1. Substrate shape is complementary to active site shape, forming enzyme-substrate complex

  2. Reaction takes place and products are released
• Optimum pH


  The optimum pH for most enzymes is 7, but some that are produced in acidic conditions, such as the stomach, have a low optimum pH
• Optimum temperature


  The optimum temperature is a range around 37 degrees celsius (body temperature)
• As temperature increases


  The rate of reaction increases up to the optimum, but above this temperature it rapidly decreases and eventually the reaction stops
• Denaturation


  When the bonds in the enzyme structure break, changing the shape of the active site so the substrate can no longer fit in
• Types of enzymes


  • Carbohydrases
  • Proteases
  • Lipases
• Carbohydrase example


  • Amylase
• Protease example


  • Pepsin
• Bile


  Alkaline to neutralise hydrochloric acid, and breaks down large drops of fat into smaller ones (emulsifies it)
• Investigating effect of pH on enzyme controlled reaction

  1. Use iodine to detect presence of starch

  2. Warm amylase, starch and buffer solution

  3. Take samples at regular intervals and record time for starch to be completely broken down

  4. Calculate rate using 1000/time
• Rate of enzymatic reactions


  Rate = change/time
• Heart


  An organ in the circulatory system that pumps blood around the body
• Double circulatory system


  1. Deoxygenated blood flows into right atrium, right ventricle, to lungs

  2. Oxygenated blood flows into left atrium, left ventricle, around body
• Heart structure


  • Muscular walls
  • Thicker wall in left ventricle
  • 4 chambers
  • Valves
  • Coronary arteries
• Heart pumping process


  Blood flows into atria, atria contract forcing blood into ventricles, ventricles contract pushing blood out
• Pacemaker


  Group of cells in right atrium that provide electrical stimulation to control heart rate
• Artificial pacemaker


  Electrical device that produces a signal causing the heart to beat at a normal speed
• Types of blood vessels

  • Arteries
  • Veins
  • Capillaries
• Arteries


  • Layers of muscle and elastic fibres to withstand high pressure
• Veins


  • Wide lumen to allow low pressure blood flow, valves to ensure one-way flow
• Capillaries


  • One cell thick walls, permeable to allow substances to move between blood and cells
• Lungs


  Supply oxygen to blood and remove carbon dioxide
• Components of gas exchange system

  • Trachea
  • Intercostal muscles
  • Bronchi
  • Bronchioles
  • Alveoli
  • Diaphragm
• Ventilation


  Ribcage and diaphragm movement changes volume and pressure, drawing air in and out
• Gas exchange


  Oxygen diffuses from alveoli into blood, carbon dioxide diffuses from blood into alveoli
• Alveoli


  • Small size and large surface area, thin walls, large blood supply to maintain concentration gradients
• Blood


  Made up of plasma, red blood cells, white blood cells and platelets
• Components of blood


  • Plasma
  • Red blood cells
  • White blood cells
  • Platelets
• Red blood cells


  • Biconcave disc shape, no nucleus, contain haemoglobin
• White blood cells


  Part of the immune system, produce antibodies