S9) The Respiratory System

Question 1

How can you locate the 2nd rib?

Answer 1

• Finding the sternal angle (between manubrium and the sternum)
• Move laterally
• Palpate the attachment of the 2nd rib

Question 2

Why is the inferior aspect of each lung curved upwards?

Answer 2

The inferior aspect lies on top of the domed diaphragm

Question 3

What sort of membranes are found in the respiratory system and what do they do?

Answer 3

• A mucous membrane; which lines the conducting portion of the respiratory tract, bearing mucus-secreting cells
• Serous membranes; which line the pleural sacs, enveloping each lung

Question 4

The pleural cavity can fill with four different substances.

What are they and what is the resulting condition named?

Answer 4

• Air – pneumothorax
• Blood – haemothorax
• Pus – empyema
• Transudate/exudate – pleural effusion

Question 5

How can fluid be drained from the pleural cavity?

Answer 5

Fluid is drained by the insertion of a wide-bore needle through an intercostal space (usually 7th posteriorly), performed under ultrasound guidance

Question 6

Identify the different lobes and respiratory airways observed in the image below:

Answer 6

Question 7

Identify the 7 components of the conducting portion of the respiratory tract

Answer 7

• Nasal cavity
• Pharynx
• Larynx
• Trachea
• Primary bronchi
• Secondary bronchi
• Bronchioles
• Terminal bronchioles

Question 8

Identify the 3 components of the respiratory portion of the respiratory tract

Answer 8

• Respiratory bronchioles
• Alveolar ducts
• Alveoli

Question 9

What does one observe as you progress down the respiratory tract?

Answer 9

The walls of the passageways become thinner as their lumens decrease in diameter

Question 10

Which components of the respiratory tract are extrapulmonary?

Answer 10

Question 11

What are the intrapulmonary components of the respiratory system?

Answer 11

Question 12

There are epithelial changes in the respiratory system.

What sort of epithelium can be found in the nasal cavity, pharynx, larynx, trachea, primary bronchi and secondary bronchi?

Answer 12

Pseudostratified epithelium, with cilia and goblet cells

Question 13

There are epithelial changes in the respiratory system.

What sort of epithelium can be found in the bronchioles and terminal bronchioles?

Answer 13

Simple columnar epithelium with cilia, Clara cells and no goblet cells

Question 14

There are epithelial changes in the respiratory system.

What sort of epithelium can be found in the respiratory bronchioles and alveolar ducts?

Answer 14

Simple cuboidal epithelium with Clara cells and a few sparsely scattered cilia

Question 15

There are epithelial changes in the respiratory system.

What sort of epithelium can be found in the alveoli?

Answer 15

• Simple squamous cells (type 1)
• Septal cells (type 2)

Question 16

Identify 3 characteristics of olfactory regions

Answer 16

• Particularly thick pseudostratified columnar epithelium
• No goblet cells
• Located in posterior, superior region of each nasal fossa

Question 17

Identify 4 characteristics of non-olfactory regions

Answer 17

• Pseudostratified ciliated epithelium
• Venous plexuses swell often to prevent overdrying
• Arterial blood flow warms inspired air
• Patency maintained by surrounding cartilage/ bone

Question 18

Identify some key anatomical features on the larynx diagram below:

Answer 18

Question 19

Describe the features of the ventricular folds of the larynx

Answer 19

• Lined by pseudostratified epithelium
• Contain mucous glands
• Contain numerous lymph nodules

Question 20

Which 2 structures contribute to the resonance of the voice?

Answer 20

• Ventricles
• Ventricular folds

Question 21

What are the components of each vocal cord of the larynx?

Answer 21

• A vocal ligament (large bundle of elastic fibres)
• A vocalis muscle (bundle of skeletal muscle)

Question 22

Identify 2 functions of the vocal cords

Answer 22

• Stop foreign objects from reaching the lungs
• Close to build up pressure when coughing is required

Question 23

The trachea divides into two primary bronchi in the mid-thorax.

How does the cartilage in these structures differ?

Answer 23

• Trachea has cartilage crescents which partially enclose the lumen
• Primary bronchi have cartilage rings which completely encircle the lumen

Question 24

What are the features of Chronic Obstructive Pulmonary Disease?

Answer 24

• There is goblet cell hyperplasia
• A smaller proportion of ciliated cells
• Hypertrophy of the submucous glands

Question 25

As bronchioles get smaller, goblet cells give way to Clara cells, interspersed between ciliated cuboidal cells. What is the role of Clara cells?

Answer 25

**Clara cells** secrete a surfactant lipoprotein, which prevents the walls sticking together during expiration

Question 26

Clara cells also secrete abundant Clara cell protein (CC16). What is the importance of this protein?

Answer 26

- A measurable marker in **bronchoalveolar lavage fluid** (lowered in lung damage) - A measurable marker in **serum**; if raised then leakage across air-blood barrier

Question 27

Which different structures can alveoli open up to?

Answer 27

- A respiratory bronchiole - An alveolar duct - An alveolar sac - Another alveolus (via an alveolar pore)

Question 28

Describe the features of alveolar walls

Answer 28

- Abundant **capillaries** - Basketwork of **elastic** and **reticular fibres** - Covering of **type I pneumocytes** - Scattering of intervening **type II pneumocytes**

Question 29

What is emphysema?

Answer 29

- **Emphysema** is a condition resulting in the destruction of alveolar walls and permanent enlargement of air spaces due from smoking or alpha 1-antitrypsin deficiency - Alveolar walls are damaged, bronchioles collapse during exhalation, so lungs cannot empty and air becomes trapped in the alveoli.

Question 30

What is a hallmark sign of emphysema?

Answer 30

Pursed-lip breathing

Question 31

What is pneumonia?

Answer 31

- **Pneumonia** is a condition involving the Inflammation of the lung by bacteria (commonly Streptococcus pneumoniae) - The lung consolidates as the alveoli fill with inflammatory cells

Question 32

Lung cancer often results in a pancoast tumour on the apex of the lung. Describe the effects of this form of cancer

Answer 32

- Tumour impinges on either **phrenic nerve** = part of diaphragm paralysed - Tumour impinges on the **brachial plexus** = muscle wasting in lower arm - Tumour impinges on the **sympathethic trunk** = Horner's syndrome - Tumour impinges on **left recurrent laryngeal nerve** = hoarse voice

Question 33

Identify the 3 hallmark signs of Horner's syndrome

Answer 33

- Miosis - Partial ptosis - Anhidrosis

Question 34

What is cohesion?

Answer 34

**Cohesion** refers to the attraction of identical molecules towards each other *e.g. H₂O molecules have strong cohesive forces due to H₂ bonding*

Question 35

Cohesive forces are responsible for surface tension. What is it?

Answer 35

**Surface tension** is the tendency of a liquid’s surface to resist rupture when placed under tension or stress *e.g. H₂O molecules at the surface will form hydrogen bonds with their neighbours*

Question 36

Lungs are surrounded by thin tissue called the pleura, a continuous membrane that folds over itself. Distinguish between the visceral and parietal pleura.

Answer 36

**- Parietal pleura** lines the chest wall **- Visceral pleura** covers the lung

Question 37

Normally, the two membranes of the lung are separated only by lubricating pleural fluid. What is the purpose of this fluid?

Answer 37

- **Reduces friction**, allowing the pleura to slide easily during breathing - **Provides the surface tension** needed to prevent the lung from recoiling and collapsing

Question 38

Normally, a vacuum (negative pressure) in the pleural space keeps the two pleurae together and allows the lung to expand and contract. Discuss this in terms of inspiration and expiration

Answer 38

- During **inhalation**, the intrapleural pressure is approximately -8cmH₂0 (below atmospheric) - During **exhalation**, intrapleural pressure is approximately -4cmH₂0 (below atmospheric)

Question 39

Demonstrates Boyle's Law in terms of volume and pressure in a container

Answer 39

- When the volume of a container increases, the pressure decreases - When the volume of a container decreases, the pressure increases

Question 40

In 4 steps, describe inhalation

Answer 40

⇒ Diaphragm contracts ⇒ Intrathoracic volume increases ⇒ Intrathoracic pressure decreases ⇒ Air moves from atmosphere into the lungs

Question 41

In 4 steps, describe exhalation

Answer 41

⇒ Diaphragm relaxes ⇒ Intrathoracic volume decreases ⇒ Intrathoracic pressure increases ⇒ Air flows out from lungs to atmosphere

Question 42

What is pressure inside the lungs called?

Answer 42

Intrapulmonary pressure

Question 43

Describe the intrapulmonary and intrapleural pressure changes

Answer 43

- **Intrapulmonary pressure** fluctuates during breathing and equalises to atmospheric pressure at end-exhalation (0 cmH₂O) - **Intrapleural pressure** also fluctuates during breathing and is ~ 4 cmH₂O less than the intrapulmonary pressure

Question 44

What is significant about the differences between intrapleural and intrapulmonary pressure?

Answer 44

The **pressure difference of 4 cmH₂O** across the alveolar wall is the force that keeps the stretched lungs adherent to the chest wall

Question 45

What happens during pneumothorax?

Answer 45

If air enters the pleural space between the parietal and visceral pleura (in pneumothorax), the -4cmH₂0 pressure gradient disappears and the lung recoils and collapses

Question 46

What is open pneumothorax?

Answer 46

**Open pneumothorax** is a condition cause by an opening in the chest wall allowing atmospheric air to enter the pleural space due to a penetrating trauma (stab, gunshot, impalement, surgery)

Question 47

What is closed pneumothorax?

Answer 47

**Closed pneumothorax** is a condition wherein atmospheric air enters the pleural space due to the rupture of the lung and visceral pleura with the chest wall still intact

Question 48

What is the role of surfactant during inhalation and exhalation?

Answer 48

- **During inhalation** – when alveoli expand, surfactant molecules move apart - **During exhalation** – when lungs shorten, surfactant molecules move together and become concentration i.e. surface tension is reduced