Organization

• 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, 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 becomes 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
• Tests for different molecules

  • Benedict's test for sugars
  • Iodine test for starch
  • Biuret test for protein
  • Emulsion test or 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 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 when 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
• Structure of the heart


  • Muscular walls
  • Thicker wall in left ventricle
  • 4 chambers
  • Valves
  • Coronary arteries
• How the heart pumps blood

  1. Blood flows into right atrium and right ventricle, then to lungs

  2. Blood flows into left atrium and left ventricle, then around body

  3. Valves ensure one-way flow
• Natural resting heart rate


  Controlled by pacemaker cells in right atrium
• Artificial pacemaker


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

  • Arteries
  • Veins
  • Capillaries
• Arteries


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


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


  • One cell thick walls for short diffusion pathway
  • Permeable walls to allow substances to move across
• Rate of blood flow


  Volume of blood/number of minutes
• Components of 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, drawing air in

  2. Opposite happens when exhaling
• Gas exchange in alveoli

  1. Oxygen diffuses from alveoli into blood

  2. Carbon dioxide diffuses from 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
• White blood cells


  Part of the immune system, defend against pathogens
• There are different types of white blood cells that produce antibodies, engulf pathogens, and coordinate the immune response