Respritory system

• Respiratory system


  The system responsible for breathing and gas exchange in the body
• Structure and function of the respiratory system

  • Structure and function of the lungs
  • Mechanics of breathing
  • Gaseous exchange at the alveoli/capillary and the capillary/muscle interface
• Functions of the respiratory system

  • Take O2 from the air and deliver it to the blood
  • Take CO2 from the blood and remove it from the body
• Epiglottis


  A flap of cartilage that stops food going into the larynx
• Pharynx/Larynx

  Also called the voice box, has folds of skin that vibrate when air passes over them
• Trachea


  A flexible tube held open by rings of cartilage
• Bronchus


  A branch of the trachea, one for each lung
• Bronchioles


  A branch of the bronchus
• Alveoli


  Tiny air sacs with very thin walls which gas can pass through - so gas exchange can occur with capillaries
• Diaphragm


  A sheet of muscle below the lungs, when it contracts it pulls air into the lungs
• Intercostal Muscles


  Located between the ribs, help the chest expand and contract
• Thoracic Cavity


  The space where the lungs are located
• Ribs


  Protect the lungs and support the intercostal muscles
• Pleural Membrane


  Protect the lungs as they rub against the ribs
• Lungs

  Soft and spongy, we have two, a left and a right, the right has three lobes, the left has two lobes due to the space taken up by the heart
• Mechanics of breathing


  1. Inspiration (breathing in)

  2. Expiration (breathing out)
• Inspiration


  Occurs actively where the intercostal muscles contract and the diaphragm contracts, causing the chest to expand and air to be drawn in
• Expiration


  Occurs passively where the intercostal muscles relax and the diaphragm relaxes, causing the chest to become smaller and air to be pushed out
• Diaphragm's role in breathing

  When the diaphragm contracts, the chest cavity enlarges, reducing the pressure inside. To equalize the pressure, air rushes into the lungs. When the diaphragm relaxes, the elasticity of the lungs and chest wall pushes air out of the lungs.
• Respiratory control centre


  Located in the brain stem, it constantly monitors oxygen and carbon dioxide levels in the bloodstream and adjusts the respiratory rate to maintain homeostasis
• If you are at rest, your body naturally inhales the right amount of oxygen and exhales the right amount of carbon dioxide and Respiratory Rate (RR) stays the same
• If you are exercising, your muscles start using the oxygen in the blood to create energy so oxygen levels decrease in the blood. Carbon dioxide is a by-product of energy production so carbon dioxide levels increase in the blood. The respiratory control centre, supported by the aorta sensors, detects this imbalance and adjusts the RR and Heart Rate (HR) accordingly.
• Gaseous Exchange


  Swapping one gas for another gas, occurs at the alveoli/capillary interface and the capillary/muscle interface
• Diffusion at the alveoli/capillary interface

  O2 passes into the lungs and moves to the alveoli then passes into the capillaries. Blood delivers O2 to cells. CO2 is brought back to the lungs and passes through the capillaries into the alveoli then leaves the lungs via the trachea.
• Diffusion at the capillary/muscle interface

  O2 is transported in the blood to working muscles and enters via the capillaries. O2 is used for energy production (ATP) and is converted to CO2. Blood delivers CO2 back to the heart to be pumped to the lungs to be exhaled.
• Tidal Volume (TV)


  The amount of air inhaled and exhaled per breath, men generally have a larger TV (600mL) compared to females (500mL)
• Respiratory Rate (RR)

  How many times you breathe in a minute
• Pulmonary Ventilation (V)


  How much air moves into and out of the respiratory tract each minute, V= RR x TV
• Ventilation at rest is approximately 12 breaths/min x 0.5L/breath = 6L/min