Gas exchange requires coordination of which organs
- lung, chest wall, respiratory muscles
- heart and pulmonary circulation
- central and peripheral nerve receptors
Pleura characteristics/fxn
- two layers: visceral and parietal
- visceral=lines lungs
- pariental=lines inside of chest wall
- pleural space=fluid filled space between pleural layers
- fxn=allows smooth movement of lungs within the thoracic cavity during inspiration and expiration
Main components of respiratory anatomy
Lobes of the lung
- 2 Left: Left Upper Lobe, Left Lower Lobe
- 3 Right: Right Upper Lobe, Right Middle Lobe, Right Lower Lobe
Conducting airways vs. Gas exchange units
- Conducting airways: trachea, bronchi, bronchioles
- Gas exchange units: respiratory bronchioles, alveolar ducts, alveoli
Structure of conducting airways
- inner mucosal surface: epithelium, cilia, goblet cells
- smooth muscle layer
- outer connective tissue
- @ transition from bronchi --> bronchioles: loss of outer cartilage
Acinus definition
- =gas-exchange region
- =respiratory bronchioles + alveolar ducts + alveoli
Types of alveolar epithelial cells
- Type I cells = "pneumocytes" = squamous lining fused w/capillary for gas exchange
- Type II cells = "secretory cells" =
- repair/replace injured Type I cells
- secrete surfacant (lowers alveolar surface tension)
- repair/replace injured Type I cells
- secrete surfacant (lowers alveolar surface tension)
Embryonic stage of lung development: events & human age
- foregut endoderm extends into mesenchyme
- 3 rounds of branching --> lung lobes
- age: 26 days -- 6 wks
Pseudoglandular stage of lung development: events & human age
-
4 rounds of branching form terminal bronchioles
-
age: 6 - 16 wks
4 rounds of branching form terminal bronchioles
age: 6 - 16 wks
Canalicular stage of lung development: events & human age
-
Terminal bronchiole divides into 2+ respiratory bronchioles
-
Surfactant production begins and increases as weeks progress
-
Age: 16 - 28 wks
Terminal bronchiole divides into 2+ respiratory bronchioles
Surfactant production begins and increases as weeks progress
Age: 16 - 28 wks
Saccular stage of lung development: events & human age
- Respiratory bronchioles subdivide to produce terminal sacs (these continue to develop well into childhood)
- Age: 28 - 36 wks
Alveolar stage of lung development: events & human age
-
Lung grows & alveoli mature:
-
Septea thin
-
Single capillary network in alveolar wall
-
Gas exchange unit established
-
Age: 36 wks -- 5 yrs
Lung grows & alveoli mature:
Septea thin
Single capillary network in alveolar wall
Gas exchange unit established
Age: 36 wks -- 5 yrs
