Breathing

• The respiratory system takes air into and out of the body so that oxygen from the air can diffuse into the bloodstream and carbon dioxide can diffuse out of the bloodstream into the air
• INHALATION

  External intercoastal muscles contract

  Ribs are pulled upwards and outwards

  Diaphragm contracts and flattens

  Volume increases

  Increased volume reduces pressure

  Air is drawn in
• EXHALATION

  External intercostal muscles relax

  Ribs move downwards and inwards

  Diaphragm relaxes and moves upwards

  Volume decreases

  Decreased volume increases the pressure

  Air is drawn out
• ADAPTATIONS OF ALVEOLI

  Membrane is one cell thick giving it a short diffusion pathway

  Surrounded by blood capillaries which maintain a concentration gradient

  Many alveoli thus increase in surface area
• Ventilator is a device that provides the pressure conditions to help a patient breathe
• There are two types of mechanical ventilator: negative pressure ventilator and positive pressure ventilator
• Negative pressure ventilators causes air to be drawn into the lungs
• Positive pressure ventilators forces air into the lungs
• ADV NEGATIVE

  Can control the amount of air drawn in

  Can be kept at home

  No surgery

  Long term
• DIS NEG

  Restricts mobility of the patient

  Complicated

  Less common nowadays

  Blood flow disruption to lower limbs
• ADV POS

  Patient is mobile

  Quick and easy

  More common

  Portable
• DIS POS

  Tube is surgically placed

  Permanent operators can mess up the rhythm

  Temporary
• IRON LUNG / NEGATIVE PRESSURE VENTILATOR

  Patient is enclosed in the device with only the head poking out

  An airtight seal is made around the neck and shoulders

  Air is pumped out of the chamber using bellows

  A vacuum is created providing negative pressure which causes the movement of the thorax to draw in air