Pleura and Lungs

Question 1

3 cavities of thorax

Answer 1

Left Pleural cavity - left lung
Right pleural cavity - right lung
Mediastinum - between the 2 pleural cavities

Question 2

What’s in the mediastinum

Answer 2

Trachea, heart, oesophagus, blood vessels, nerves

Question 3

Development of lungs and pleura

Answer 3

development begins in 4-6 week old embryos from the endoderm layer
Endoderm continues to divide into out-pouches called lung buds that push out
Rapid division of the airways
Lungs push out into the primitive thoracic cavity and take visceral pleura with them

Question 4

pericardioperitoneal cavity

Answer 4

primitive thoracic cavity

Question 5

2 layers of pleura

Answer 5

Visceral - covers the lungs

Parietal pleura

Question 6

Between pleura

Answer 6

Pleural cavity

Question 7

Visceral Pleura

Answer 7

Sticks to lungs and fissures
Creates smooth surface
Connects parietal pleura and the hilum of the lung
Primary bronchus enters here

Question 8

Parietal Pleura

Answer 8

Divided into 4 parts

1. Costal (internal rib cage)
2. Mediastinal (lateral wall of mediastinum)
3. Diaphragmatic ( superior diaphragm)
4. Cervical (cervical region)

Question 9

Pleural Cavity

Answer 9

There is a thin layer of serous fluid which allows the pleura to slide against each other
Surface tension of the serous fluid = cohesion to help the lungs be held against the thoracic wall

Question 10

Recess

Answer 10

Costomediastinal recess - where the heart sits so parietal pleura goes over the visceral pleura
Costodiaphragmatic recess - natural recess at the inferior end of the pleural cavity

Question 11

Pleural Innervation:

Parietal

Answer 11

Cervical - 1st intercostal nerve

Costal - intercostal nerves

Mediastinal - phrenic nerve

Diaphragmatic - lower intercostal and phrenic nerves

Pain sensitive

Question 12

Pleural innervation:

Visceral

Answer 12

Autonomic nervous system - from pulmonary plexuses

No pain sensitivity cos don’t have any sensation nerves

Question 13

What’s in the lungs?

Answer 13

Apex
Base - in contact with the diaphragm
lobes created by fissures (pulmonary ligament holds up the lower lobe)

Question 14

Surfaces on the lung

Answer 14

Costal - in contact with rib
Mediastinal
Diaphragmatic

Question 15

Borders of the lung

Answer 15

Anterior, inferior, posterior

Question 16

Right lung

Answer 16

3 lobes: Superior, middle, inferior
2 fissures: Horizontal, oblique (inferior superior split)
Is the larger, heavier, shorter and wider than left
Shorter cos liver is encroaching onto the inferior aspect

Question 17

Left lung

Answer 17

2 lobes: superior and inferior 
1 fissure: oblique 
Cardiac notch 
Lingula - drapes over heart
2 lobular bronchi

Question 18

Hilum

Answer 18

Formed by structures from mediastinum entering the lungs:
Main bronchus
Pulmonary artery (superior)
Bronchial arteries and veins - supply lung tissue
Pulmonary plexus of nerves - plexus of nerves from autonomic nervous system
Lymph vessels and nodes

Question 19

Pulmonary circulation

Answer 19

De-oxygenated blood from right ventricle enters lung via right pulmonary artery
Oxygenated blood returns to left atrium via left or right superior or inferior pulmonary veins

Question 20

Bronchial circulation

Answer 20

Bronchial arteries supply O2/nutrients to lungs and visceral pleura
Left arteries branch from descending aorta
Right arteries branch from intercostal arteries
Bronchial veins terminate in the azygous veins

Question 21

Respiratory tree

Answer 21

Trachea –> primary bronchi –> secondary bronchi (lobar) –> tertiary bronchi (segmental) –> Bronchioles –> alveolar sacs –> alveoli

Question 22

Trachea

Answer 22

Flexible tube that rubs from larynx, runs from C6 to T4/5
Composed of c-shaped cartilage rings
Has trachealis muscle posteriorly to allow expansion
Lined by a mucus membrane and cilia - moistens and warms air as it comes in and wafts excess mucus
Bifurcates at sternal angle
Internal point of bifurcation - carina

Question 23

Primary Bronchi

Answer 23

One for each lung, passing into lung at hilum
Right main bronchus is wider, shorter and runs more vertically
Contains cartilage

Question 24

Secondary bronchi

Answer 24

lobar supplies one lobe each so 3 in the right lung and 2 in the left lung

Question 25

Tertiary Bronchi

Answer 25

Each tertiary bronchus supplies a bronchopulmonary segement (aka segmental bronchi)

Question 26

Bronchopulmonary segments

Answer 26

Usually 10 in right lung
8-10 in left lung Each one is the largest subdivision of a lobe
Supplied by a single tertiary bronchus
Receives a single branch of the pulmonary artery
Separated by connective tissue - surgically resectable/ removable in isolation
layer of connective tissue

Question 27

Bronchioles

Answer 27

20-23 generations of conducting bronchioles
No cartilage in walls
Terminal bronchiole gives rise to several generations of respiratory bronchioles
Respiratory bronchioles characterised by out pockets of alveoli

Question 28

Alveoli

Answer 28

Alveolar ducts are elongated airways lined by alveoli which leads to common spaces - Alveolar sacs
Surrounded by capillaries

Question 29

2 cell types of alveoli

Answer 29

Type 1 pneumocytes (95%)
Type 2 pneumocytes (5%) secrete pulmonary surfactant - secreted into interior of alveolus - provides cohesive ability to bring walls together

Question 30

Innervation of lung:

Sympathetic:

Answer 30

From sympathetic trunk: fight or flight so smooth muscle dilates to let more air in
Bronchial musculature -dilates
Pulmonary vasculature -constricts

Question 31

Innervation of lung: Parasympathetic

Answer 31

From vagus: rest and digest
Bronchial musculature -constricts cos don’t need as much air
Pulmonary vasculature -Dilates

Question 32

Lymph drainage

Answer 32

Drains towards the hilum via bronchopulmonary nodes
3 Groups: drainage of lymph from periphery of lungs all the way up
1. Bronchial pulmonary lymph nodes
2. Where trachea splits into bronchi - bronchial tracheal lymph nodes
3. Travels up to the paratracheal lymph nodes - either side of trachea
Eventually drain into venous system of subclavian veins
Anything pathological may flow through the lymph nodes going up