-have lungs
-increased surface area for O & CO
-air taken through the mouth and/or nostrils & passes through trachea
-network of branches-lead to alveoli (called bronchi)
-allow more intake of air
-areas gas exchange takes place
-oxygen replaced by carbon dioxide from capillaries
-excess carbon dioxide pumped through bronchi ~ through trachea ~ and exhaled through mouth and/or nostrils

Fetal pig