Station 1 and 2

Question 1

At what vertebral levels does the trachea start and end?

Answer 1

Begins at termination of the larynx and C6/7 and terminates as it bifurcates into the L and R primary bronchi (at the carina) at the T4/5 plane (also the level of the sternal angle)

Question 2

What structures are anterior to the trachea in the neck?

Answer 2

Isthmus of the thyroid gland, strap muscles, steinocleinomastoids. *Recurrent laryngeal nerves ascend the neck either side of the trachea

Question 3

Where is a tracheotomy performed?

Answer 3

Between C rings 2 and 3, or 3 and 4

Question 4

What structures are anterior to the trachea in the superior mediastinum?

Answer 4

The manibrium, the thymus, the arch of aorta and its branches (the brachipcephalic trunk, and then the left common carotid and subclavian are more to the left), the SVC, the left and right brachipcephalic veins, fat

Question 5

What structures lie posterior to the trachea, in both the neck and superior mediastinum?

Answer 5

The oesophagus and the cervical and thoracic vertebrae.

Question 6

What type of epithelium is in the trachea>

Answer 6

Respiratory epithelium

Question 7

How many tracheal rings are there?

Answer 7

16-20

Question 8

What is the functional significance of the C-shaped cartilage rings remaining open posteriorly?

Answer 8

They are closed posteriorly by the trachealis muscle (smooth muscle). Allows ithe oesophagus to bulge out into the tracheea whilst swallowing a bolus of food.

Question 9

What changes occur in the trachea of a heavy smoker?

Answer 9

Stratified squamous metaplasia

Question 10

What are the cells of the respiratory epithelium?

Answer 10

Ciliated columnar cells - motile cilia sweep particulate matter through mucous, upwards to it can be coughed up or swallowed
Goblet cells - secrete mucous
Basal cells - step cells that can differentiate into other respiratory epitheium cells ininjury
Brush cells - chemmo- and general sensory cells
Granule cells - endocrine cells

Question 11

What are the differences between the L and R primary bronchi? What is the significance of this?

Answer 11

R is wider and descends more steeply. Also, as the carina is located slightly left of midline, this means aspirated objects are more likely to end up in the R lung

Question 12

What is the carina?

Answer 12

Cartilagenous ridge at the bifurcation of the trachea. Located slightly left of midline at the T4/5 plane

Question 13

How many primary bronchi are there on the L and R?

Answer 13

2 on the left (upper and lower lobes) and 3 on the right (upper, middle and lower lobes)

Question 14

How many tertiary bronchioles in the L and R lungs? What do they supply?

Answer 14

Supply bronchopulmonary segments.

Right: 10
3 to the upper lobe, 2 to the middle lobe, 5 to the lower lobe.

LEft: 8-10
4-5 to the upper, 4-5 to the lower.

Question 15

What shape is a bronchopulmonary segment? Significane?

Answer 15

cone/wedge shape.
Each is supplied by a bronchopulmonary artery. If there is a PE etc, in one of these, the result is a wedge shaped infarct.

Question 16

When are bronchi considered bronchioles?

Answer 16

When they becomes 1mm or less in diameter

Question 17

What is a lobule? What airway segment supplies it?

Answer 17

Lobule is a hexagonal segment that constitutes the smallest visible division of the lungs. Supplied by a terminal bronchiole.

Question 18

Changes to epithelium within the bronchi

Answer 18

Bronchi are originally histologically identical to the trachea. As they enter the lungs, they begin to change. With decreasing airway diameter there is a:

Gradual reduction in epithelial cell height
Less continuous hyaline cartilage
Few goblet cells
Fewer submucosal glands
The originally thick basement membrane of the trachea becomes thinner

Question 19

Changes to the epithelium from the bronchioles to the respiratory bronchioles.

Answer 19

In the bronchioles:
Gradually decreasing epithelial cell hight, presence of clara cells begins.

Terminal Bronchioles:
Simple cuboidal epithelium

Respiratory Bronchioles:
Simple Cuboidal Epithelium interrupted by alveoli

Question 20

Changes in smooth muscle from bronchi to respiratory bronchioles

Answer 20

Bronchi: ‘Muscalaris’ layer of the bronchial wall is continuous, becomes slightly less so

Bronchioles: Relatively thick smooth muscle layer, compared to their size

Respiratory: Knobs of muscle occasionally present, w/ simple cuboidal epithelium covering them. More proximally this epithelium is ciliated cuboidal cells and clara cells. More distaly, becomes mainly clara cells.

Question 21

CHages in goblet cells from bronchi to bronchioles

Answer 21

Gradually decreasing numbers of goblet cells as bronchial diameter decreases,

Gradually replaced by clara cells in bronchioles, then disappear

Question 22

CHanges in the cartilage from bronchi to bronchioles

Answer 22

Within bronchi, becomes less continuous, develop cartilage ‘plates’

No cartilage plates in bronchi, but occasional elements of cartilages at branchings

Question 23

How does a respiratory bronchiole differ from a terminal bronchiole

Answer 23

Terminal bronchioles and respiratory bronchioles both have a simple cuboidal epithelium. Respiratory bronchioles have more clara cells. Alveoli interrupt the walls of respiratory bronchioles, but are not present in terminal bronchioles.
Terminal bronchioles = the last division of the conducting airways, and Respiratory bronchioles = the first of the respiratory zone