(add diagram) Respiratory System

• breathing


  the mechanical ventilation of the lungs to inhale and exhale air
• nasal cavity structure


  3 ridges of bone within the cavity increases the folding, therefore increasing the surface area

  very large blood supply (close capillaries)

  large hairs found at the opening prevent large objects entering

  lined by elongated epithelial cells with microscopic ‘hair like’ projections called cilia
• nasal cavity function


  creates turbulence in the air - dust and particles are caught on the mucus membranes and nasal hairs

  air is warmed and moistened

  specialised sensory cells give us a sense of smell
• pharynx structure


  region/space at the back of the mouth
• pharynx function


  passage for both food and air
• epiglottis structure


  a small flap of tissue- mainly elastic cartilage
• epiglottis function


  fits over the trachea when swallowing to prevent food entering the trachea/lungs
• larynx structure


  a region below the pharynx that contains the vocal sords supported by cartilage
• larynx function


  sound production as air moves out of the lungs and flows over the vocal chords
• trachea structure


  tube from pharynx down to the two bronchi - lined by pseudostratified ciliated epithelium and supported by C shaped rings of hyaline cartilage
• trachea function


  cartilage holds the trachea open for air movement and prevents collapse of the airway

  ciliated epithelium along its length cleans the air with mucus that traps dust and pathogens
• bronchi structure


  two tubes that act as division of the trachea into the right and left lungs

  held open by cartilage rings, lined by ciliated epithelium
• bronchi function


  a pathway for air passage - cartilage rings stop airways collapsing
• bronchioles structure


  tiny last segments of tube after the bronchi, which air passes through before reaching alveoli

  no cartilage rings present
• bronchioles function


  air passage towards the alveoli
• alveoli structure


  the smallest structure at the end of the bronchioles - round air sacs

  the walls of the alveoli are only one cell thick (simple squamous epithelium)

  they always have a thin layer of moisture lining the inner surface

  round shape provides a large surface area

  large capillary network covers the sacs
• alveoli function


  simple squamous epithelium creates a thin, delicate, moist membrane in direct contact with the blood supply for gas exchange through diffusion
• pleural membrane structure


  membrane covering the outer surface of the whole lung and the internal surface thoracic cavity
• pleural membrane function


  produces pleural fluid which acts to reduce friction as the lung moves within the thoracic cavity

  fluid also ensures that the lung remains attached to the inner wall of the thoracic cavity
• diaphragm structure


  sheet of muscle and tendon which separates the thoracic cavity from the abdominal cavity
• diaphragm function


  contracts and relaxes to allow ventilation of the lungs/breathing
• intercostal muscles structure


  skeletal muscles found between the ribs
• intercostal muscles function


  aids in the movement of the ribs for the ventilation of the lungs/breathing
• nasal conchae


  ridges of bone covered in mucous membrane which line the nasal cavity and prepare inhaled air to enter the lungs
• almost all oxygen (97%) is taken up and carried by erythrocytes once it diffuses through the alveolus wall
• haemoglobin


  the iron carrying protein found on the erythrocyte surface that transports the oxygen around the circulatory system
• most carbon dioxide (70%) is carried dissolved in the plasma as bicarb ions
• if too much carbonic acid accumulates in the blood, it can lead to the pH of the blood decreasing