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, substances that increase 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 - carbohydrates to simple sugars
  • Proteases - proteins into amino acids
  • Lipases - lipids into fatty acids and glycerol
• 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 for different molecules

  • Benedict's test for sugars - brick red
  • Iodine test for starch - black blue
  • Biuret test for protein - purple
  • Emulsion test or Sudan III test for lipids - cloudy layer or red layer
• Bile


  • Produced in the liver and stored in the gallbladder, released into the small intestine
  • Alkaline to neutralise hydrochloric acid
  • Emulsifies large fat droplets to increase surface area for lipase
• 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
• 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

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


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


  • One cell thick walls for short diffusion pathway
  • Permeable walls to allow substances to move between blood and cells
• Gas exchange system


  Trachea, intercostal muscles, bronchi, bronchioles, alveoli, diaphragm
• Ventilation


  Ribcage and diaphragm move to increase volume and decrease pressure, drawing air into lungs
• Gas exchange in alveoli

  1. Oxygen diffuses from alveoli into blood

  2. Carbon dioxide diffuses from blood into alveoli
• Alveoli


  • Small size and clustered arrangement for large surface area
  • Thin walls for short diffusion pathway
  • Large blood supply to maintain concentration gradient
• Blood


  Composed of plasma, red blood cells, white blood cells and platelets
• Red blood cells


  • Biconcave disc shape for large surface area
  • No nucleus to allow more space for haemoglobin
  • Contain haemoglobin to bind oxygen
• White blood cells


  Part of the immune system, defend against pathogens
• Types of white blood cells

  • Those that produce antibodies
  • Those that engulf and digest pathogens
  • Those that coordinate the immune response
• Alveoli


  Very thin, meaning there is a short diffusion pathway
• Calculating breathing rate


  Divide the number of breaths by the number of minutes