Respiratory System 2

Respiratory System 2

1. Trachea

   • Horseshoe shaped rings of cartilage with ends connected posteriorly by the trachealis muscle (smooth)
   • Conducts air into thorax
   • Withstands stretch
   • Transports mucous blanket
   • Mucosa
     • Epithelium: PSCC (+Goblet cells)
     • Lamina propria- large amounts of elastic fibres
   • Submucosa
     • Seromucous acinar glands
   • Adventitia
     • Loose CT reinforced by 16-20 C-shaped rings of cartiliage

2. Bronchi

   • PSCC (+goblet cells)
   • Seromucous glands
   • Extrapulmonary Cartilage: Complete C-shaped rings
   • Intrapulmonary Cartilage: incomplete plates
   • Spirally arranged smooth muscle
   • Moves air in and out of lungs
   • Main - L + R,
   • Lobar - 2L + 3R
   • Segmental -8L+ 10R

3. Bronchopulmonary segments

   • Morphologically and functionally seperate and independent respiratory units of lung tissue
   • Supplied by tertiary bronchus
   • Each segment surrounded by CT can be removed without affecting othersegments
   • 10 segments in right lung and 8 in left lung

4. Bronchioles

   • <1mm diameter
   • Conducts air into respiratory passageways
   • Simple columnar/cuboidal epithelium
   • NO glands and NO cartilage
   • Prominent smooth muscle
   • Gradual decrease of cilia and goblet cells
   • Clara cells
     • Protect bronchiolar epithelium
     • Secrete solution similar to surfactant

5. Alveoli

   • Simple squamous epithelium
   • Type I pneumocytes - gas exchange
   • Type II pneumocytes - surfactant production
     • Surfactant reduces surface tension
   • Elastic and reticular fibres
   • capillaries: mid-wall
   • Alveolar macrophages

6. Asthma

   • Chronic lung disease- inflames and narrows airways
   • Increased contractibility of smooth muscle in airways
   • Thickened basement membrane
   • Swelling of mucosa
   • Increase in mucous production