TRACHEA

• Trachea (windpipe) - allows air to flow into the lungs; reinforced by 15-20 C-shaped pieces of hyaline cartilage
• Tracheobronchial tree - consists of the trachea and all other respiratory passageways in the lungs (bronchioles)
• Bronchodilation - occurs when the smooth muscle relaxes, making the bronchiole diameter larger
• Bronchoconstriction - occurs when smooth muscle contracts, making the bronchiole diameter smaller; happens during asthma attacks