Pleura and the lungs

Question 1

Describe the development of the pleura and the lungs

Answer 1

Occurs from weeks 4-6
Arises from the endoderm
Lung buds arise from endodermal pouches
Early lung structures include the pleurocardioperitoneal canals and the pleuropericardia membrane

RAPID DIFFUSION

Visceral pleura and parietal pleura form given rise to pleural cavity

Question 2

Describe the function of the visceral pleura

Describe its innervation

Answer 2

It creates a smooth and slippery surface
Connects to parietal and hilum of lung

Autonomic system innervation via pulmonary plexus
Insensitive to pain

Question 3

Describe the parietal pleura and its innervation

Answer 3

Cervical- 1st intercostal nerve
Costal- intercostal nerves
Mediastinal- phrenic nerve
Diaphragmatic- lower intercostal nerves and phrenic nerve

Question 4

What is the function of the serous fluid between the pleura?

Answer 4

Allows pleura to slide over each other

Surface tension provides cohesions to help lung expand as thoracic cavity expand

Question 5

What is a recess?

Describe the two recesses in the lung

Answer 5

A space between the lung and the parietal pleura

Costomediastinal recess: larger on the left side due to heart

Costodiaphragmatic recess: during normal breathing the space occupies about 2 ribs e.g. the lower border of the lung lies on the plane of the 6th rib midclavicularly, 8th rib on the mid-axillary line, and the T10 posteriorly whereas parietal pleura: 8,10,12. During expiration, costodiaphragmatic recess increases and lung rises higher

Question 6

Describe some difference between the right and left lung

Answer 6

Right lung larger, heavier
Divided into three lobes (superior, middle, inferior) by the horizontal and oblique fissures

Left lung is smaller
has a cardiac notch and lingula
Divided into 2 lobes (superior,inferior) by the oblique tissue

Question 7

Which structures pass through the hilum?

Answer 7

1. Pulmonary artery (2)
2. Pulmonary vein (4)
3. At the hilums of both lungs, the right lung possesses two bronchi and the left lung possesses only one bronchus.
4. Bronchial arteries/veins
5. Pulmonary plexus of nerves
6. Lymph vessels and nodes (paratracheal nodes, tracheobronchial nodes, bronchopulmonary nodes)

Question 8

Describe the bronchial circulation

Answer 8

Bronchial arteries supply the lung and visceral pleura
Left superior arteries from descending aorta at T5
Left inferior arteries from descending aorta inferior to left bronchus
Right arteries from 3rd posterior intercostal artery (or superior left bronchial artery)

Venous drainage
Pulmonary veins
Azygos vein on RHS, superior intercostal vein/hemiazygos/accessory hemiazygos on LHS

Question 9

What is the function of the pulmonary ligament?

Answer 9

It is a fold of pleura that stabilises position of inferior lobe and accomodates the down/up translocation of structures in root during breathing

Question 10

Describe innervation of bronchial musculature and pulmonary musculature

Answer 10

Sympathethic (trunk)- dilation, constrict

Parasympathetic (vagus)- constrict, dilation

Question 11

Outline and describe where appropriate, the respiratory tree

Answer 11

Trachea- c-shaped cartilage anteriorly, trachealis muscle posteriorly. lined by mucus and cilia, internal bifurcation point=carina

Main bronchi- contain cartilage, LHS wider shorter and more horizontal

Lobar bronchi- 3 in RHS, 2 in LHS

Segmental bronchi- each supply 1 bronchopulmonary segment

Bronchioles- NO cartilage, 20-25 conducting zone generations, terminal bronchiole= respiratory bronchiole (alveolar sacs)

Alveoli- type 1 pneumocytes (95%), type 2 pneumocytes produce surfactant

Question 12

What is a bronchopulonary segment?

Answer 12

Largest subdivision of lung
Surgically resectable
Separated by connective tissue
Single branch of pulmonary artery supplies each
10 on RHS, 8-10 on LHS