anatomy of the respiratory tract

• FUNCTIONS OF THE RESPIRATORY TRACT:

  1. provides oxygen to all body tissues
  2. removes carbon dioxide
  3. regulates blood pH
  4. defence against pathogen
  5. produces sound
  6. olfaction (smell)
• UPPER RESPIRATORY TRACT (nose, pharynx, paranasal sinuses, larynx)

  1. warms and moistens and filters the air
  2. olfaction
  3. resonates sound

  NOSE:

  • warms, moistens and filters air
  • contains receptors for smell
  • modifies speech sounds
• FUNCTIONAL ADAPTATIONS OF THE NOSE:

  VIBRISAE:

  • hairs at entrance to nose which rasp large dust particles

  CONCHAE:

  • shelf like projections from lateral wall
  • produces turbulence which allows more time to warm and moisten air

  MUSCOSA:

  • pseudostratisfied ciliated columnar epithelium with goblet cells
  • goblet cells produce mucous to trap particles
  • cilia waft the mucous trapped particles to pharynx where they can be swallowed
• FUNCTIONAL ADAPTATIONS OF THE NOSE P2.

  • Rich capillary network underlies the mucosa: circulating blood warms the air
  • Olfactory mucosa: located in upper aspect of the nose, contains receptors for smell
  • Paransal sinuses: air filled spaces that drain into nasal cavity, lighten the skill and resonate sound
• PHARYNX

  • forms a communal passageway for respiratory and gastrointestinal systems
  • there's 3 regions:

  1. NASOPHARYNX- posterior to nose
  2. OROPHARYNX- posterior to mouth
  3. LARYNGOPHARYNX- posterior to larynx
• LARYNX

  • main function includes:

  1. maintains an open airway
  2. prevents door and drink entering the lower respiratory tract
  3. sound production

  • also involved in coughing and defaecation
  • consists of a cartilaginous skeleton; lined by membranes and moved by muscles
• LOWER RESPIRATORY TRACT- trachea, bronchi, bronchus

  TRACHEA

  • tough, flexible rube, 4.5cm, 2.5cm in diameter
  • extends from larynx to the carina, lies anterior to the oesophagus
  • contains 15-20 horseshoe shaped cartilage which keep airways open
  • posterior ends of cartilage and joined by tracheal muscle, which constricts during coughing
  • trachea lined with pseudostratified ciliated columnar epithelium
• BRONCHI

  • series of tubes that gets smaller in diameter and displays other histological changes

  1. amount of cartilage decreases
  2. amount of smooth muscle increases
  3. height of epithelial cells decrease
• BRONCHI HISTOLOGY

  • PRIMARY BRONCHI

  1. supply each lung
  2. 2-3 cm long
  3. right is wider and more vertical than left
  4. C-shaped cartilage

  • SECONDARY BRONCHI (lobar)

  1. supply lobes of the lung (3 on right, 2 left)
  2. plates of cartilage

  • TERITARY BRONCHI (segmental)

  1. supply segments of the lung (10 on right, 8 left)
  2. plates of cartilage
• BRONCHUS

  • psuedostratisfied ciliated columnar epithelium with goblet cells
  • cartilage plates
• BRONCHIOLAR STRUCTURE

  BRONCHIOLES

  • no cartilage
  • smooth muscle therefore can constrict and dilate
  • each give rise to 50-80 terminal bronchioles

  TERMINAL BRONCHIOLES

  • simple columnar epithelium with cilia
  • no goblet cells or mucous glands
  • Clara cells- produce surfactant
  • each gives rise to 2 or more respiratory bronchioles

  RESPIRATORY BRONCHIOLES

  • simple cuboidal epithelia
  • Clara cells- produce surfactant
  • no cilia
  • alveoli extend from lumen - gas exchange occurs here
• RESPIRATORY MEMBRANE

  1. epithelium of type I cell
  2. basement membrane of type I cell
  3. basement membrane of capillary
  4. endothelium of capillary

  • the two basement membranes tend to be fused together
• FUNCTIONAL ORGANISATION OF THE HEART

  • the conductive is concerned with filtering, warming and moistening the air and conducting the air into the lungs
  • the respiratory portion includes all parts of the tract where gas exchange takes place

  -->respiratory bronchioles, alveolar ducts, alveolar sacs, alveoli