respiratory system

• conducting airways

  pseudostratifed columnar ciliated epithelium with goblet cells
• PaO2 = arterial partial pressure of oxygen
• there needs to be enough oxygen for basal metabolism
• PaCO2 is linked to a pH or roughly 7.4
• the left lung is smaller due to the heart
• lungs are surrounded by the pleural membrane
• the wall of the lung is covered by the visceral pleura
• entry point into the lungs is the hillum
• the tertiary bronchi feed each lung segment
• layers of capillaries: simple squamous epithelium, basement membrane, endothelium, basement membrane
• alveoli is surrounded by elastic fibres and capillaries
• respiration


  pulmonary ventilation, external respiration, transport of respiratory gases, internal respiration
• pulmonary ventilation

  movement of air into and out of the lungs
• external respiration

  movement of oxygen from the lungs to the blood, and from blood to the lungs
• transport of respiratory gases

  transport of oxygen from lungs to the tissue cells, and co2 from the tissue cells to lungs
• internal respiration

  movement of oxygen from blood to tissue cells, and co2 from tissue cells to the blood
• lungs are separated by the heart and mediastinum
• the cardiac notch is where the heart lies
• upper respiratory tract

  nasal cavity, pharynx
• lower respiratory tract

  larynx, trachea, bronchial tree
• the trachea is between the 7th and 5th thoracic vertebrae
• carina

  point of division into primary bronchi
• mucosa

  pseudostratified ciliated epithelium with goblet cells
• 3 lobes on the right, and 2 lobes on the left
• type 1 alveolar cells

  single layer of squamous epithelial cells
• type 2 alveolar cells

  cuboidal epitheliums secreting surfactant
• partial pressure gradient drives movement
• ventilation and perfusion maintain partial pressure differences between air and blood
• ventilation

  continually renewing air that is in contact with membrane
• perfusion

  right ventricle of the heart pumping blood through pulmonary circulation
• flow is proportional to the pressure difference between two points and is inversely proportional to resistance
• inspiration

  goal is to increase volume of thoracic cavity, requires ADP, diaphragm flattens and increases height of thoracic cage, external intercostal muscles increase width of thoracic cage
• the diaphragm can increase volume of thoracic cavity above normal volume by using pec minor and major
• expiration

  passive process, inspiratory muscles relax, ribcage descends, lungs recoil, thoracic and intrapulmonary volume decreases
• forced expiration

  use of accessory muscles (abdominal and internal intercostals), active process
• haemoglobin has cooperative binding, once it binds to oxygen, the shape changes and other sites are more likely to bind to oxygen
• central controller of breathing is the brainstem
• the dorsal respiratory group outputs to diaphagm and EIM and causes them to contract
• factors altering ventilation

  brain centres, peripheral chemoreceptors, stretch receptors, irritant receptors, proprioreceptors