B2 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 working 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
• How enzymes work (Lock and Key Hypothesis)

  1. Substrate binds to active site of enzyme

  2. Reaction takes place

  3. Products released
• 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
• Optimum pH and temperature for enzymes

  • Optimum temperature is around 37 degrees celsius (body temperature)
  • Optimum pH for most enzymes is 7, some have a low optimum pH
• As temperature increases


  Rate of reaction increases up to optimum, then rapidly decreases
• If pH or temperature is too high or low


  Enzyme is denatured and can no longer work
• Types of enzymes


  • Carbohydrases
  • Proteases
  • Lipases
• Examples of carbohydrases, proteases and lipases

  • Amylase
  • Pepsin
  • Enzymes produced in pancreas and small intestine
• Soluble glucose, amino acids, fatty acids and glycerol pass into the bloodstream to be carried to all the cells around the body</b>
• Tests to determine composition of a solution

  • 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 and stored in the gallbladder, released into the small intestine
  • Alkaline to neutralise hydrochloric acid
  • Emulsifies large fat droplets
• 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 until starch is completely broken down

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

  Rate = change/time
• Heart


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


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


  Two circuits - deoxygenated blood to lungs, oxygenated blood around body
• Parts of the heart

  • Right atrium
  • Right ventricle
  • Left atrium
  • Left ventricle
  • Muscular walls
  • Valves
  • Coronary arteries
• How the heart pumps blood

  1. Blood flows into atria

  2. Atria contract, forcing blood into ventricles

  3. Ventricles contract, pumping blood to lungs and body

  4. Valves close to prevent backflow
• Pacemaker


  Group of cells in right atrium that provide electrical stimulation to make the heart beat
• 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


  • Carry blood away from the heart
  • Layers of muscle and elastic fibres to withstand high pressure
• Veins


  • Carry blood towards the heart
  • Wide lumen to allow low pressure blood flow
  • Valves to ensure one-way flow
• Capillaries


  • Allow blood to flow close to cells for substances to move between them
  • One cell thick walls for short diffusion pathway
  • Permeable walls
• Rate of blood flow

  Volume of blood/number of minutes
• Parts of the gas exchange system

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


  1. Ribcage moves up and out, diaphragm moves down, increasing volume and decreasing pressure

  2. Air drawn in from high to low pressure
• Gas exchange


  1. Oxygen diffuses from alveoli into capillary blood

  2. Carbon dioxide diffuses from capillary blood into alveoli
• Alveoli


  • Small and arranged in clusters for large surface area
  • Capillaries provide large blood supply
  • Thin walls for short diffusion pathway
• Breathing rate


  Number of breaths/number of minutes
• 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