The respiratory tract moves air to the lungs for oxygen and carbon dioxide exchange, but it also provides a route through which microbes can enter and spread. This lesson introduces the major respiratory structures and the defenses that help keep inhaled microbes from reaching vulnerable lung tissue.
The respiratory tract is commonly divided into upper and lower regions near the epiglottis, a structure that helps seal the airway during swallowing.
All flashcards
What is the mucociliary escalator?
It is the coordinated action of mucus trapping particles and cilia moving that mucus upward toward the epiglottis, where it can be swallowed or expelled.
What is the path from the nares to the larynx?
Air passes from the nares into the nasal cavity, then through the nasopharynx, oropharynx, and laryngopharynx before reaching the larynx.
What is the path from the larynx to the alveoli?
Air travels through the trachea, bronchi, and bronchioles before reaching the alveoli, where gas exchange occurs.
What connects the nasopharynx to the middle ear?
The eustachian tube connects the nasopharynx with the middle ear.
How do alveolar macrophages protect the lungs?
These phagocytic immune cells engulf and kill microbes that reach the lower respiratory tract despite earlier defenses.
Quiz questions
How do the microbial populations of the upper and lower respiratory tracts generally compare?Answer: The upper tract has abundant, diverse populations; the lower tract has few detected microbes.
What role do adhesins play in respiratory infection?Answer: They help pathogens attach to respiratory epithelial cells.
How can a bacterial polysaccharide capsule help a respiratory pathogen?Answer: It can reduce the likelihood that immune cells will phagocytose the bacterium.
What can be true of Staphylococcus aureus in a healthy person's nose?Answer: It may be carried without causing illness.
Which vaccine helps protect against serious disease caused by Haemophilus influenzae type b?Answer: The Hib vaccine.
Based on Microbiology by Nina Parker, Mark Schneegurt, Anh-Hue Thi Tu, Philip Lister, Brian M. Forster (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.