Key to Alveoli of lung - Model ALV 1
1	Intrappulmonary bronchi
2	Non-cartilaginous bronchioles
3	Respiratory bronchioles
4	alveoli
5	mucus membrane
6	elastic fibers
7	smooth muscle
8	pulmonary plexus
9	mucus glands of the bronchi
10	fibro-cartilaginous layer
11	pulmonarhy pleura
12	limiting membranes
13	dense capillaries
14	collaginous fibers
15	elastic fibers
16	epithelium
17	bronchial vein plexus
18	pulmonary vein (high oxygen, low carbon dioxide)
19	pulmonary artery (low oxygen, high carbon dioxide)
20	bronchial artery (supplies the tissues of the lungs, does not pick up oxygen)
21	anastomosis between bronchial arteries and pulmonary veins
22	alveolar capillary network
23	anastomosis of an obstructed artery with pulmonary vein
24	dense capillary network
25	anastomosis between pulmonary artery and vein