Structure of the Lungs

Question 1

Tell me four facts about the trachea

Answer 1

Palpable anteriorly, above suprasternal notch
• C-shaped rings of hyaline cartilage supporting a fibro-elastic and muscular air-transport tube
• Starts at C6, ends at T 4/5 (sternal angle) at carina
• Trachealis muscle (posteriorly positioned) alters tracheal diameter
Trachea

Question 2

Why are foreign bodies more likely to enter the right lung?

Answer 2

Its size and shape, the right main bronchus is slightly more vertical, shorter and wider than the left.

Question 3

Tell me about the lobes of the lung

Answer 3

the left lung has two lobes whereas the rich lobe is comprised of three lobes, however they both have one main bronchus.

Question 4

How are the bronchi supplied with oxygen

Answer 4

they are supplied OXYGENATED blood via the bronchial arteries

Question 5

Tell me about lobar bronchi

Answer 5

Since the left lung has two lobes its has two secondary bronchi, the superior and inferior. The right lung however has three lobes so three secondary lobar bronchi, the superior, middle and inferior

Question 6

Bronchioles

Answer 6

Bronchi continue to divide into smaller and smaller branches becoming conducting bronchioles, and then respiratory bronchioles, always decreasing in diameter and eventually becoming alveoli

Question 7

What is the volume of mucus produced per day?

Answer 7

1.5 litres

Question 8

In the bronchi the epithelial cells are still, pseudo stratified, ciliated, columnar but they are what?

Answer 8

They are slightly flattened compared to the trachea

Question 9

As the bronchi move into the lungs the c-shaped cartilage is replaced by what?

Answer 9

cartilage plates

Question 10

Tell me about the transformation from the bronchial tree to the bronchioles

Answer 10

they have a lumen of less than 1mm in diameter , the epithelium cells become ciliated columnar (thinner and flatter) and are in a surrounding band of smooth muscle. The cartilage and glands disappear and the bronchiole is held open by the surrounding lung tissue

Question 11

What happens in asthma

Answer 11

the smooth muscle surrounding the bronchioles in the wall may excessively narrow the lumen

Question 12

Tell me about the terminal and respiratory bronchioles

Answer 12

The epithelium in these bronchioles becomes non-ciliated cuboidal and the goblet cells disappear

Question 13

Where does gas exchange occur

Answer 13

in the respiratory alveoli that bud from the respiratory bronchioles

Question 14

Where are alveoli found

Answer 14

the outpocketings of respiratory bronchioles, alveolar ducts and alveolar sacs. They are separated by septa which is a thing layer containing capillaries, these are the air blood barrier for gas exchange

Question 15

What is pleura

Answer 15

membranes which cover the lungs as well as the cavity walls

Question 16

What is the pleural cavity

Answer 16

the space between the layers of pleura

Question 17

What are the four different names for parietal pleura

Answer 17

cervical
costal
Mediastinal
Diaphragmatic

Question 18

How are the lungs separated

Answer 18

by the mediastinum

Question 19

Tell me about the left lung

Answer 19

slightly longer and narrower, predominantly to make room for the heart and pericardium, the space for the heart is called the cardiac notch

Question 20

What keeps the lungs partially inflated

Answer 20

The negative pressure from the pleura cavities

Question 21

What causes a collapsed lung

Answer 21

Air in the pleural cavity

Question 22

Whats the general relationship between artier and veins in terms of blood

Answer 22

arteries = oxygenated
veins = deoxygenated

Question 23

How do we drain lymph fro the lung

Answer 23

via a sub-pleural plexus and a plexus alongside the bronchi to hilarious lymph nodes

Question 24

What is the hilum

Answer 24

The root of the lung where the main structures pass into and out of the lung

Question 25

Tell me about the right lung

Answer 25

Slightly wider and shorter, mainly due to dome of the diaphragm being higher on the left side

Question 26

Where is the trachea located

Answer 26

The sternal notch, if deviated could be a tumour or collapsed lung

Question 27

Tell me about the positioning of the lungs

Answer 27

The apex is above the clavicle
inferiorly the lungs ends two rib spaces higher than the bottom of the cage
Normal respiration does not extend to the lower parts of the pleural cavity

Question 28

Overview of the mechanisms of respiration

Answer 28

• Respiration varies from quiet during rest through to a range of forced respirations during severe exercise or respiratory distress.
• Inhalation/Inspiration must increase the diameters of the thorax to create a negative pressure, which sucks air into the lungs via the trachea and larynx etc.
• Diaphragmatic contraction causes its descent, increasing its vertical diameter.
• Rib elevation (with assistance from intercostal muscles) pushes the sternum up and forward, and the ribs outward, to increase anteroposterior and lateral diameters.
• Exhalation/Expiration is by muscle relaxation (passive) and elastic recoil (remember the high amount of elastic tissue in the lungs and bronchi).

Question 29

What expands the capacity of the ribs

Answer 29

the intercostal muscles expand the size of the thoracic cavity during inspiration and raise the ribs pushing the sternum outwards.

Question 30

Tell me about the diaphragm

Answer 30

muscular at the periphery
tendinous at its centre
left and right domes
motor and sensory supply is the phrenic nerve (C3.C4.C5 Keep the diaphragm alive)