2.1 Respirotary System

• Outline 3 functions of the conducting airways:

  1. Warm and Moisten air - air in the nose is warmed and moistened so it enters the lungs in a wet state

  2. Low resistance pathway for airflow - air funnelled into pharynx air pressure is lowered

  3. Defence against chemicals and other harmful substances that are inhaled - larynx prevents food & fluid from entering the lungs
• Pulmonary Ventilation = inflow and outflow of air between atmosphere and lungs (breathing)
• Tidal Volume = the volume of air breathed in and out in one breath

  • imcreases during excercise
• Expiratory Reserve volume (ERV) = volume of air in excess of tidal colume that can be exhaled forcibly

  • slightly decreases during excercise
• Residual Volume = volume of air still contained in lungs after a maximim exhalation

  • no change during excercise
• Vital Capacity = maximum volume of air that can be exhaled after a maximal inhalation

  • slightly decreases during excercise
• Vital capacity = tidal volume + Inspiratory Reserve Volume + Expiratpry reserve volume
• Total Lung Capacity = Vital Capacity + Residual Volume
• Inhalation begins with the diaphragm contracting, moving downwards and opening up, increasing lung volume, allowing air in.
• During inhalation, intercostal muscles contract, pushing the rib cage upwards and outwards, increasing the size of the lungs.
• Exhalation begins with the intercostal muscles relaxing, allowing the diaphragm to relax, decreasing the size of the lungs.
• Air always moves from an area of high pressure to an area of low pressure.
• In order to get air into the lungs, pressure needs to be lower inside the lungs than in the air we are breathing.
• In order to expel air from the lungs (exhale), pressure needs to be higher in the lungs than in the air.
• High lung volume = low pressure -> air forced in from atmosphere

   

  Low lung volume = high pressure -> air forced into atmosphere

   

   
• • Breathing rate increases during exercise as the expiratory centre sends impulses to the expiratory muscles (internal intercostal) which speed up the expiratory process

   

  • Increase of CO2 causes acidity of blood to increase - change in acidity of blood is detected by chemoreceptors which send nerve impulses to the respiratory muscles which increase the rate of ventilation
• Chemoreceptors: 

   

  • Detect chemical change in blood (blood acidity / PH )
  • If increase CO2 - breathing rate & debt increased
  • If decreased CO2 - decreased breathing rate & debt 
• Proprireceptors:

   

  • Detect angle movements at joints

   

  • Increased movement - increased breathing rate & depth
  • Decreased movement - decreased breathing rate & depth
• Stretch receptor: 

   

  •   inhibits inspiration and stimulutes expiration after a large inhalation to prevent over stretching of the lungs  
• Heamoglobin = protein that allows oxygen to bind to a red blood cell
• 98.5 % of O2 in blood is transported by heamoglobin as oxyhemoglobin - oxygen atoms then diffused into tissues once they reach target
• Oxygen enters the blood and binds with the Iron (HEME) within haemoglobin molecules) 

   

  • Each haemoglobin molecule can transport 4 oxygen molecules

   
• 2.1.6 Outline role of heamoglobin in oxygen transport

   

  Heamoglobin = protein that allows oxygen to bind to a red blood cell

   

  98.5 % of O2 in blood is transported by heamoglobin as oxyhemoglobin - oxygen atoms then diffused into tissues once they reach target

   

   

  Oxygen enters the blood and binds with the Iron (HEME) within haemoglobin molecules) 

   

  • Each haemoglobin molecule can transport 4 oxygen molecules

   

   
• 2.1.7 explain process of gaseous exchange at alveoli

   

   

  Structure of alveoli: 

   

  • Very thin walls - 1 cell thick
  • Huge surface area - for greater uptake of oxygen
  • Supplied by dense capillary network

   

  • Passive diffusion between alveoli and capillaries
  • Oxygen diffuses from alveoli into capilaries 
  • Carbon dioxide diffuses from capilaries into alveoli