organisation

• Cells


  Make up all living things
• Tissue


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


  • Muscular tissue
  • Epithelial tissue
• Organ


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


  • Stomach
• Organ system


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


  • Digestive system
• Organs in the digestive system

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


  Biological catalysts that increase 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 pH at which an enzyme works best, usually around 7 but some have a low optimum pH
• Optimum temperature


  The temperature range around 37 degrees Celsius (body temperature) at which an enzyme works best
• Temperature increases


  Rate of reaction increases up to optimum, then rapidly decreases and stops
• Denaturation


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


  • Carbohydrases
  • Proteases
  • Lipases
• Carbohydrase example


  • Amylase
• Protease example


  • Pepsin
• Soluble glucose, amino acids, fatty acids and glycerol pass into the bloodstream to be carried to all the cells around the body
• Tests for biological molecules

  • Benedict's test for sugars
  • Iodine test for starch
  • Biuret test for protein
  • Emulsion test for lipids
  • Sudan III test for lipids
• Bile


  Produced in the liver, stored in the gallbladder, released into the small intestine. Alkaline to neutralise stomach acid, emulsifies fats.
• 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 test with iodine

  4. Time when starch is completely broken down

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


  Calculated using change/time
• Heart


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


  Carries oxygen and nutrients to every cell in the body and removes waste products
• Double circulatory system


  1. Deoxygenated blood flows to the right atrium and right ventricle, then to the lungs

  2. Oxygenated blood flows to the left atrium and left ventricle, then around the body
• Heart structure


  • Muscular walls
  • Thicker left ventricle wall
  • 4 chambers
  • Valves
  • Coronary arteries
• Blood flow through the heart

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


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


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


  • Arteries - carry blood away from the heart, have muscular and elastic walls

  Veins - carry blood towards the heart, have wide lumen and valves

  Capillaries - allow blood to flow close to cells for diffusion
• Lungs


  Found in the thorax, supply oxygen to blood and remove carbon dioxide
• Components of the gas exchange system

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


  1. Ribcage moves up and out, diaphragm moves down, increasing chest volume and decreasing pressure, drawing air in

  2. Opposite happens when exhaling
• Gas exchange


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


  • Small size and clustered arrangement for large surface area

  Capillaries provide large blood supply

  Thin walls for short diffusion pathway
• 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 for large surface area

  No nucleus for more space to carry oxygen

  Contain haemoglobin to bind oxygen
• White blood cells


  Part of the immune system, defend against pathogens