Lungs and Pleura Flashcards
Development of lungs and pleura
respiratory system begins to develop at 4-6 weeks from endoderm layer
endodermal out pouches form lung and bronchial buds
rapid division
Visceral Pleura
Closely adheres to the lungs including the fissures
Creates a smooth and slippery surface
Connects to the parietal pleura and hilum/root of the lung
Parietal pleura
Lines the internal aspects of the thoracic wall
Divided into 4: costal, mediastinal, diaphragmatic, cervical
Pleural Cavity
contains a layer of serous fluid
surface tension of the serous fluid holds lungs against thoracic wall and prevents collapse
There are 2 PC recesses due to heart - costomediastinal and costodiaphragmatic
Pleural Innervation
cervical: 1st intercostal nerve
costal: intercostal nerves
mediastinal: phrenic nerve
diaphragmatic: phrenic & lower intercostals
pulmonary plexuses supply visceral layer
Trachea
flexible tube running form C6 to T4/5
bifurcates at level of sternal angle
lined by mucous membrane and cilia
the carina separates the 2 main bronchi
Bronchi
Primary - one for each trunk (not symmetrical)
Secondary (lobar) - supply one lobe each
Tertiary (segmental) - supplies a bronchopulmonary segment
Bronchopulmonary segments
10 in right, 8 in left
supplied by a single tertiary bronchus
separated by connective tissue
surgically resectable
Bronchioles
20-25 generations of conducting bronchioles
No cartilage in walls
Characterised by out pockets of alveoli
Lead into alveolar ducts which end in alveolar sacs
Alveoli
Surrounded by capillaries
2 types: type 1 (95%) and type 2 (5% and secrete surfactant)
Innervation of the Lungs
Sympathetic: form sympathetic trunk - bronchial musculature dilates and vasculature constricts
Parasympathetic: from Vagus nerve - bronchial musculature constricts and vasculature dilates
Bronchial Circulation
Bronchial arteries supply lung and visceral pleura
Left arteries branch from descending aorta
Right arteries branch from intercostal arteries
Bronchial veins terminate in Azygos system of veins