Explanation

Alveoli and their ducts. Respiratory System [table] Conducting Portion | Respiratory Portion ; The conducting portion provides a passage for the air. It conditions the incoming air by warming, moistening and cleaning it. It consists of nasopharynx, larynx, trahea, bronchi, bronchioles and terminal bronchioles | The respiratory portion consisting bronchioles, alveolar ducts and alveolar sacs, serves to get rid the body of $CO_{2}$ and pick up oxygen. This system is derived from the endoderm [/table]