Topic 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
• Organs


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


  • Stomach
• Organ systems


  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
• If the pH or temperature is too high or too low, the enzyme becomes denatured and can no longer work
• Types of enzymes


  • Carbohydrases (convert carbohydrates into simple sugars)
  • Proteases (convert proteins into amino acids)
  • 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 different molecules

  • Benedict's test (for sugars, turns brick red)
  • Iodine test (for starch, turns blue-black)
  • Biuret test (for protein, turns purple)
  • Emulsion test (for lipids, adds ethanol resulting in a cloudy layer)
  • Sudan III test (for lipids, red layer forms on top)
• Bile


  • Produced in the liver and stored in the gallbladder, then released into the small intestine
  • Alkaline to neutralise hydrochloric acid from the stomach
  • Emulsifies large fat droplets into smaller ones to increase surface area for lipase
• Investigating the effect of pH on an 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
• 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 (carry blood away from heart)
  • Veins (carry blood towards heart)
  • Capillaries (allow close contact between blood and cells)
• 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

  2. Air drawn in from high to low pressure
• 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
• Blood


  Composed of 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, produce antibodies, engulf pathogens, respond to infection
• Alveoli


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


  Divide the number of breaths by the number of minutes
• Components of blood


  • Plasma
  • Red blood cells
  • White blood cells
  • Platelets
• Plasma


  Liquid that carries the components in the blood: red blood cells, white blood cells, platelets, glucose, amino acids, carbon dioxide, urea, hormones, proteins, antibodies and antitoxins
• Red blood cells


  • Carry oxygen molecules from the lungs to all the cells in the body
  • Biconcave disc shape provides a large surface area
  • No nucleus allowing more room to carry oxygen
  • Contain the red pigment haemoglobin, which binds to oxygen and forms oxyhaemoglobin
• White blood cells


  • Part of the immune system, which is the body's defence against pathogens (microorganisms that can produce disease)
  • Have a nucleus
  • Types: those that produce antibodies against microorganisms, those that engulf and digest pathogens, those that produce antitoxins to neutralise toxins produced by microorganisms
• Platelets


  • Help the blood clot form at the site of a wound
  • The clot dries and hardens to form a scab, which allows new skin to grow underneath while preventing microorganisms from entering
  • Small fragments of cells
  • No nucleus
  • Without them, cuts would result in excessive bleeding and bruising
• Coronary heart disease


  When the coronary arteries that provide blood to the heart become blocked with the build up of fatty material, resulting in less blood flowing to the heart and reducing its oxygen supply, which may lead to a heart attack