Composition of the Normal Respiratory Tract

Trachea
C-shaped plates of cartilage anteriorly & smooth muscle posteriorly
Pseudo-stratified, columnar 'respiratory' epithelium

Mucous glands

Bronchus
Discontinuous foci of cartilage and continuous smooth muscle
Pseudo-stratified, columnar 'respiratory' epithelium
Mucous glands

Non-respiratory Bronchiole
No cartilage
Continuous smooth muscle
Pseudo-stratified, columnar 'respiratory' epithelium
No mucous glands

Respiratory Bronchiole & Alveolar Ducts
No cartilage
Discontinuous smooth muscle
Flat single layer epithelium
No mucous glands/goblet cells

Alveoli

Flat single layer epithelium
Type I & Type II pneumocytes