Respiratory System
Functions
 Provide large area for gas exchange between air and
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circulating blood
Move air to and from the gas exchange surfaces of
the lungs
Protect the respiratory surfaces from dehydration
and temperature changes and defending against
invading pathogens
Produce sounds permitting speech, singing, and
non-verbal auditory communication
Provide olfactory sensations to the central nervous
system for sense of smell
The Respiratory Tract
 Conducting portion
 Begins at entrance to nasal cavity
 Continues through the pharynx, larynx, trachea, bronchi, and
larger bronchioles
 Delivers air to lungs
 Filters, warms, and humidifies the air
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Protecting alveoli from debris, pathogens, and environmental
extremes
 Respiratory portion
 Includes smallest bronchioles and alveoli
 Gas exchange
Structures
 Nose
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Air enters through external nares (nostrils), which open into nasal
cavity
Coarse hairs across nostrils protect from large airborne particles
Mucus coats lining of nasal cavity
Protects from small airborne particles
 Promotes filtration, warming, and humidifying of incoming air
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 Pharynx
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Throat
Shared by respiratory and digestive systems
Extends between internal nares and entrances to larynx and
esophagus
Structures
 Larynx
 Air leaves pharynx and enters larynx through opening called
glottis
 Voice box
 Epiglottis extends above glottis to protect during swallowing
 Houses vocal cords
 Trachea
 Windpipe
 Bronchi
Structures
 Bronchioles
 Alveoli
 Lungs
 Lungs have spongy consistency due to air-filled passageways
and alveoli
 Pleural Cavities
 Cavities that house the lungs