Unit 2: 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
• Enzyme catalysis


  1. Substrate binding

  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
  • Each enzyme has its own uniquely shaped active site where the substrate binds
• Lock and Key Hypothesis

  The shape of the substrate is complementary to the shape of the active site, so when they bond it forms an enzyme-substrate complex
• Optimum pH and temperature for enzymes

  • Optimum temperature is around 37 degrees celsius (body temperature)
  • Optimum pH for most enzymes is 7, but some have a low optimum pH
• If the temperature or pH is too high or too low, the enzyme will be denatured and can no longer work
• Types of enzymes


  • Carbohydrases
  • Proteases
  • Lipases
• Carbohydrases


  Convert carbohydrates into simple sugars
• Example carbohydrase


  • Amylase
• Proteases


  Convert proteins into amino acids
• Example protease


  • Pepsin
• Lipases


  Convert lipids into fatty acids and glycerol
• 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 and stored in the gallbladder, then released into the small intestine
  • It is alkaline to neutralise the hydrochloric acid from the stomach
  • It breaks down large drops of fat into smaller ones (emulsifies it)
• Investigating the effect of pH on an enzyme controlled reaction

  1. Warm a solution of amylase, starch and a buffer solution

  2. Take drops of the solution at regular points and place in wells with iodine

  3. The time for the starch to be completely broken down is recorded and the rate is calculated
• Rate of enzymatic reactions


  Rate = change/time
• Heart


  An organ in the circulatory system, pumps blood around the body in a double circulatory system
• Chambers of the heart

  • Right atrium
  • Right ventricle
  • Left atrium
  • Left ventricle
• Structure of the heart

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

  1. Blood flows into the right atrium and left atrium

  2. The atria contract forcing the blood into the ventricles

  3. The ventricles then contract, pushing the blood into the pulmonary artery and aorta
• Pacemaker


  Group of cells in the right atrium that provide stimulation through small electrical impulses to control the natural resting 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


  • Carry blood away from the heart
  • Layers of muscle and elastic fibres in the walls
• Veins


  • Carry blood towards the heart
  • Wide lumen
  • Have valves
• Capillaries


  • Allow blood to flow very close to cells
  • One cell thick walls
  • Permeable walls
• 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 into the lungs

  2. The opposite happens when exhaling
• Gas exchange


  1. Oxygen diffuses from the alveoli into the capillary bloodstream

  2. Carbon dioxide diffuses from the blood to the alveoli
• Alveoli


  • Very small and arranged in clusters, creating a large surface area
  • Capillaries provide a large blood supply
  • Walls are very thin
• Blood


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