Structures of the respiratory system

Nasal cavity

Upper respiratory; air enters through nares/nostrils that are lined by a mucous membrane

Paranasal sinuses

UR; Air-filled cavities that surround the nasal cavity; reduce skull’s weight, produce mucus, and influence voice quality by acting as resonating chambers; four in total: maxillary, ethmoid, sphenoid, and frontal

Pharynx

UR; AKA the throat; passageway serving both respiratory and digestive systems

Larynx

UR; AKA the voice box; lies between pharynx and trachea; air vibrates the vocal folds to create sound

Trachea

UR; AKA the windpipe; main airway to the lungs; divides into two large branches, the primary bronchi, which channel air to the right or left lung

Lungs

Lower respiratory; expand and contract to supply oxygen to tissues all over the body and dispose of carbon dioxide; enclosed in double-layered serous membrane called the pleura which also divides lungs into lobes; right lung = 3 lobes; left lung = 2 lobes + room for the heart

Bronchi & bronchioles

LR; Network of intricate passages that supply the lungs with air; subdivide smaller and smaller in branches called bronchioles; terminal bronchioles conduct air to the alveoli of the lungs

Alveoli

LR; air sacs at end of bronchiole’s end; walls of alveoli exchange oxygen and carbon dioxide between air in lungs and blood in capillaries

Diaphragm

LR; Muscular sheet between base of lungs and abdominal cavity; contraction and relaxation = breathing