BIO 342
Comparative Vertebrate Anatomy
Lecture Notes - Respiratory System

Respiration is the process of obtaining oxygen from the external environment & eliminating CO2.

Adaptations for external respiration:

    1 - Primary organs in adult vertebrates are external &  internal gills, swim bladders or lungs, skin, & the buccopharyngeal mucosa

    2 - Less common respiratory devices include filamentous outgrowths of the posterior trunk & thigh (African hairy frog), lining of the cloaca, & lining of esophagus

Respiratory organs:

Swim bladder & origin of lungs - most vertebrates develop an outpocketing of pharynx or esophagus that becomes one or a pair of sacs (swim bladders or lungs) filled with gases derived directly or indirectly from the atmosphere. Similarities between swim bladders & lungs indicate they are the same organs.

Vertebrates without swim bladders or lungs include cyclostomes, cartilaginous fish, and a few teleosts (e.g., flounders and other bottom-dwellers).

Swim bladders:


Lungs & associated structures


  Trachea <---> primary bronchi <---> secondary bronchi <---> tertiary bronchi <---> bronchioles <---> alveoli

Related links:

Chordate Respiratory Organs and Functions

Back to BIO 342 syllabus