L1.3 Lungs, pleura, bronchial tree

Question 1

Branches of airway:

1) Trachea

Answer 1

• starts lower border of cricoid cartilage → to T4/5 where it bifucates (at the plane of Louis)
• ‘U’ shape cartilaginous ridge (deficient POS)
• POS deficiency bridged by muscles
  
  • Deficiency allows expansion of airway → prevents collapse

Question 2

2) 2 main bronchi

Answer 2

• R → shorter & wider
• Hilum = where bronchi enters lungs
  
  • L enters before divide
  • R divides before entering (SUP & INT (divides into middle & lower))

Question 3

3) Lobar bronchi

Answer 3

• Each goes to single lobe of lung
• 3R, 2L lobes

Question 4

4) segmental bronchi

Answer 4

• 9/10 segments of lungs

Question 5

5) Bronchioles

Answer 5

• Cartilaginous support ↓ further distally → changes from bronchi → bronchiole (when cart lost)
• Bronchiole → respiratory bronchiole → alveoli

Question 6

Asthma

Answer 6

• involves spasm of S.M ~ lower airways
• No cartilaginous support → collapses → difficult breathing
• Cold air makes asthma worsen → triggers S.M spasm

Question 7

What is the position of weakness in the thoracic area

Answer 7

• SUP apertures → expose lungs → position of weakness

Question 8

BS to lungs

Answer 8

• Pulmonary blood supply for gas exchange, follows similar branching pattern as airways
• A (carry DeO2) → branches of pul. Trunk ( blood to lungs)
  
  • Hilum position: SUP & POS
• V (carry O2) → blood towards heart
  
  • Hilum position: INF & ANT
• Pressure difference b/w A & V are very small (Thickness difference not as great as other A & V)

Question 9

Bronchial supply to lungs

Answer 9

• Supplies parenchyma (non-respiratory parts - i.e not alveoli)
• Derived from bronchial A which is a branch of descending aorta → branches down to smaller levels

Question 10

Venous drainage

Answer 10

• Bronchial veins → azygous vein

Question 11

Bronchopulmonary segments

Answer 11

• Pyramid shaped with ‘apex’ towards hilum and base on surface
• Supplied by segmental bronchus, A & V
• Functionally distinct
• Surgically resected without disrupting other lung units

Question 12

Structures on the R medial surface

Answer 12

• A - SUP & POS
• V - INF & ANT
• 2 lobar bronchi

Question 13

Impressions on the R lung

Answer 13

• SVC, R Brachiocephalic V, Azygous, Cardiac impression

Question 14

Structures on the L medial surfcae

Answer 14

• Single LMB
• A - SUP
• V - INF & ANT

Question 15

Impressions on the L lung

Answer 15

• Arch of aorta, Descending aorta, cardiac impression

Question 16

N supply to the lungs

Answer 16

• Parasym: From vagus N (10th cranial N)
  
  • Over arch of aorta → behind LMB → branch to bronchiole tree
• Sym: T1-4
  
  • Synapse at sym ganglia → branches towards bifurcation
  • Inhibits S.M around bronchi

Question 17

Lymphatics of the lungs

Answer 17

• Vessels → nodes → trunks → Duct (R lymphatic & thoracic) → Vein (Subclavin)
• Deep pul lymphatic vessels
• SUP lymphatic vessels
  
  • Both drain via hilum lymph nodes → tracheal nodes → bronchomediastinal trunk
• Macrophages aggregate in lymph nodes → macrophage presents carbon (may be black in colour as a result)

Question 18

Pleura

Answer 18

• Closed, double layer membrane surrounding each lung
• Vis & Parietal
  
  • May have costodiaphragmatic recess in parietal (results in diaphragm moving down)

Question 19

What is the pulmonary ligament

Answer 19

• Pulmonary ligament → parietal pleura extended down from hilum
• At the point of reflection → allows structures into lungs

Question 20

Development of the pleura

Answer 20

• Coelom → viscera moves in & enlarges → double layer membrane surrounds it

Question 21

N supply to the pleura

Answer 21

• Visceral → same sensory N which innervates visceral
  
  • Visceral afferent - T1-4 from sym
• Parietal → from somatic N located adjacent to membrane
  
  • Phrenic, intercostal

Question 22

Importance of surface tension from pleura

Answer 22

• important for breathing
• Broken/punctured → lung collapses