RESPIRATORY

• Most common place for infectious agents to gain access to the body

  Respiratory system
• Mouth, nose, nasal cavity, pharynx, epiglottis, larynx

  Upper respiratory tract
• Trachea, bronchi, bronchioles, and alveoli


  Lower respiratory tract
• Anatomical defenses:

  • nasal hairs
  • ciliated epithelium of trachea & bronchi ( ciliary escalator)
  • mucus
  • coughing
  • sneezing
  • swallowing
• Anatomical defenses:

  nasal hair traps particles
• Anatomical defenses:

  the ciliary escalator propel particles upward and out of the respiratory tract
• Anatomical defenses:

  • Mucus lining the respiratory tract is a natural trap for invading microorganisms
  • Once the microorganisms are trapped, involuntary responses such as coughing, sneezing, and swallowing can move them out of sensitive areas.
• Coughing, sneezing, swallowing

  First-line defenses
• Second & third-line defenses:

  • Complement action in the lungs
  • increased levels of cytokines and antimicrobial peptides
  • Macrophages inhabit the alveoli of the lungs and the clusters of lymphoid tissue (tonsils) in the throat
  • secretory IgA
• The respiratory tract harbors a large number of ____ microorganisms due to its constant contact with the external environment

  Commensal
• _____ major bacterial genera make up a significant portion of normal biota

  Nine
• This yeast colonizes the mucosal surfaces of the mouth in the upper respiratory tract

  Candida albicans
• Normal biota plays a significant role in _____ _____

  microbial antagonism
• Nine major genera in normal biota:

  • Prevotella
  • Sphingomonas
  • Pseudomonas
  • Acinetobacter
  • Fusobacterium
  • Megasphaera
  • Veillonella
  • Staphylococcus
  • Streptococcus
• Normal biota that can cause disease:

  • S. pyogenes
  • H. influenzae
  • S. pneumoniae
  • N. Meningitidis
  • S. aureus
• Infectious Diseases Manifesting in the Upper Respiratory Tract

  Common cold, sinusitis, Acute Otitis Media, Pharyngitis
• Infectious Diseases Manifesting in Both the Upper and Lower Respiratory Tracts

  Whooping cough, Respiratory synctial virus disease, Influenza
• Infectious Diseases Manifesting in the Lower Respiratory Tract

  Tuberculosis, Community-Acquired Pneumonia, Healthcare-associated Pneumonia, Hantavirus Pulmonary syndrome
• Help warm and moisten the air

  Sinuses
• Serve as chemical signals in the presence of foreign microorganisms

  Cytokines
• Revealed that upper & lower respiratory tracts harbor normal biota

  Metagenomic analysis