2. LUNGS Two compound saccular organs that constitute the basic respiratory organ of airbreathing vertebrates, that normally occupy the entirelateral parts of the thorax and consist essentially of an inverted tree of intricately branched bronchioles communicating with thin walled terminal alveoli swathed in a network of delicate capillaries where the actual gaseous exchange.
3. The right lung has three lobes and the left lung has two.