Respiratory System

• nasal passages 


  eustachian tube, middle ear, mastoid cavities
• pharynx and larynx 


  back of nasal cavities is continuous with the throat region or phraynx, pharynx leads to the larynx. the larynx is the vocal cord
• epiglottis


  flap that automatically closes off the larynx when swallowing or drinking and prevents fluid from entering the lungs
• alveoli type 1

  • squamous and extremely thin 

  • 95% of alveolar surface
• muscociliary escalator 


  Cilia beat upwards pushing the mucus secreted by the goblet cells assisted by the cough reflex
• upper respiratory tract 


  nasal cavity, pharynx, larynx
• lower respiratory tract


  trachea, bronchi, lungs
• surfactant


  a phospholipid acts as a detergent and reduces surface tension to prevent alveoli from collapsing
• Surface tension


  produced by fluid in lining of lung
• Surface Area


  480 million alveoli in two lungs, surface area 70-85 m2
• Respiratory Distress Syndrome in Premature Babies 


  not enough surfactant (type 2 alveoli) in the lungs, lung expansion is difficult and alveoli collapse
• Treatment of Respiratory Distress Syndrome

  mechanical ventilation, oxygen therapy and synthetic or natural surfactants
• lobes in right lung

  3
• lobes in left lung

  2
• intrapulmonary pressure


  the pressure inside the lung decreases as lung volume increases during inspiration; pressure increases during expiration
• intrapleural pressure


  pleural cavity pressure becomes more negative as chest walls expand during inspiration. returns to initial value as chest wall recoils
• volume of breath 


  during each breath, the pressure gradients move 0.5 litres of air into and out of the lungs
• Pneumothorax


  collapsed lung, results from loss of negative intrapleural pressure
• dalton's law 


  a mixture of gases the total pressure of the mixture is the sum of the individual gases
• Oxygen-carrying capacity


  maximum amount of oxygen that haemoglobin can transport
• Oxygen content


  actual amount of oxygen bound to haemoglobin
• Oxygen saturation


  ratio of oxygen content to oxygen-carrying capacity
• left shift


  increased affinity for oxygen
• right shift 


  decreased affinity for oxygen
• carbon dioxide transported in the blood through

  dissolved in solution, bound in proteins, bicarbonate ions
• Haldane effect


  helps lungs release CO2 from haemoglobin
• Bohr effect


  helps O2 release from oxyhaemoglobin