Lungs and Pleura

Question 1

Development of lungs and pleura

Answer 1

respiratory system begins to develop at 4-6 weeks from endoderm layer
endodermal out pouches form lung and bronchial buds
rapid division

Question 2

Visceral Pleura

Answer 2

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

Question 3

Parietal pleura

Answer 3

Lines the internal aspects of the thoracic wall

Divided into 4: costal, mediastinal, diaphragmatic, cervical

Question 4

Pleural Cavity

Answer 4

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

Question 5

Pleural Innervation

Answer 5

cervical: 1st intercostal nerve
costal: intercostal nerves
mediastinal: phrenic nerve
diaphragmatic: phrenic & lower intercostals
pulmonary plexuses supply visceral layer

Question 6

Trachea

Answer 6

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

Question 7

Bronchi

Answer 7

Primary - one for each trunk (not symmetrical)
Secondary (lobar) - supply one lobe each
Tertiary (segmental) - supplies a bronchopulmonary segment

Question 8

Bronchopulmonary segments

Answer 8

10 in right, 8 in left
supplied by a single tertiary bronchus
separated by connective tissue
surgically resectable

Question 9

Bronchioles

Answer 9

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

Question 10

Alveoli

Answer 10

Surrounded by capillaries

2 types: type 1 (95%) and type 2 (5% and secrete surfactant)

Question 11

Innervation of the Lungs

Answer 11

Sympathetic: form sympathetic trunk - bronchial musculature dilates and vasculature constricts
Parasympathetic: from Vagus nerve - bronchial musculature constricts and vasculature dilates

Question 12

Bronchial Circulation

Answer 12

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