specification

• aerobic respiration as a process that occurs in cells when oxygen is available
• respiration as a series of enzyme-controlled reactions within the cell, that use glucose and oxygen to release energy and produce carbon dioxide and water;
• energy is released in the form of ATP
• Use germinating peas to show that energy is released as heat during respiration.
• anaerobic respiration as a process that occurs in the absence of oxygen
• anaerobic respiration - glucose being broken down to release energy and lactic acid
• oxygen debt as a result of anaerobic respiration
• anaerobic respiration as a less efficient process than aerobic respiration because of the incomplete breakdown of glucose
• less ATP is produced per molecule of glucose in anaerobic respiration than in aerobic respiration
• Lactic acid is harmful to the body
• Lactic acid has to be removed from cells and broken down following the resumption of aerobic respiration (to repay the oxygen debt)
• respiratory system -

  A) nasal cavity

  B) trachea

  C) lung

  D) bronchus

  E) bronchioles

  F) alveoli

  G) pleural cavity

  H) intercostal muscles

  I) ribs

  J) diaphragm

  
• Mucus and cilia help protect the respiratory system
• Particles and bacteria stick to mucus and cilia move the mucus out of the respiratory system to the back of the throat.
• inspiring -

  • intercostal muscles contract
  • rib cage moves up and out
  • diaphragm becomes flatter when the muscle contracts
  • low pressure in the thorax due to increased volume
• expiration -

  • intercostal muscles relax
  • rib cage moves down and in
  • diaphragm becomes dome-shaped when the muscle relaxes
  • high pressure in thorax due to decreased volume
• The bell jar model, which is air tight, represents the thorax, and air is only able to enter via the glass tube which represents the trachea.
• As the rubber sheet is pulled down the volume of the jar increases, the pressure therefore decreases and air is drawn in through the glass tube inflating the balloons, which represent the lungs.
• structure - Glass tube/trachea

  similarities - Allows air to pass through, splits into two

  differences - Glass is rigid and inflexible unlike the cartilage bound trachea
• structure - Bell jar/chest cavity

  similarities - Air tight

  differences - Unable to move, the ribs can move up and out to increase the volume of the thorax
• structure - Balloons/lungs

  similarities - Can inflate and deflate, are elastic like the alveoli

  differences - The balloons are large open spaces whereas the lungs are made up of millions of individual elastic alveoli
• structure - Rubber sheet/diaphragm

  similarities - Can be domed up to decrease the volume in the jar

  differences - The diaphragm only flattens, it is not pulled downwards like the rubber sheet
• The composition of inspired air:

  21% Oxygen

  0.04% Carbon Dioxide

  78% Nitrogen

  percentage of water vapour varies.
• The composition of expired air:

  16% Oxygen

  4% Carbon Dioxide,

  78% Nitrogen

  saturated with water vapour.
• The adaptations of alveoli for gas exchange include

  • large surface area
  • thin wall
  • moist lining
  • rich blood supply.
  • These adaptations maximise the rate of diffusion of oxygen and carbon dioxide
• There are chemicals in cigarette smoke which paralyse cilia and particles which clog the mucus which prevents their function.
• preventing the cilia's function increases the risk of disease in the respiratory system
• Tar in tobacco smoke contains carcinogens which lead to lung cancer
• Cigarettes also contain nicotine which is addictive
• Cigarette smoke destroys lung tissue which leads to emphysema
• The amount of oxygen required to remove the lactic acid, and replace the body's reserves of oxygen, is called the oxygen debt.