Respiratory strand: Lecture 5 - Physiology of the Airway

Question 1

Explain the anatomy of the upper airway (image)

Answer 1

slide 2 image

Question 2

What happens when the pressure in our airway drops?

Answer 2

• airway has pressure receptors that detect when the pressure drops
• sends efferent message to the vagus nerve
• causes pharyngeal muscles to contract harder
• this is rapid and critical

Question 3

Name two sleeping disorders and their prevalence?

Answer 3

• snoring (25%)

- sleep apnoea (10%)

Question 4

What are the clinical features of apnoea?

Answer 4

• snoring
• daytime somnolence
• associated with: obesity and hypertension

Question 5

How do you treat sleep apnoea?

Answer 5

• weight loss

- CPAP (continuous positive airway pressure: keeps air at higher pressure than atmospheric)

Question 6

Where do you find cilia epithelial cells & goblet cells?

Answer 6

Nose
Pharynx
Trachea
Bronchi
Bronchioles

Question 7

What is the function of cilia epithelial cells & goblet cells?

Answer 7

to produce airway lining fluid

Question 8

Why are mucin granules released?

Answer 8

To protect the lungs in response to:

• airway irritation
• tobacco smoke
• infection

Question 9

What is periciliary layer?

Answer 9

water with salt

Question 10

What is cilia inhibited by?

Answer 10

• tobacco smoke
• inhaled anaesthetics
• air pollution
• infections

Question 11

What are the two functions of airway lining fluid?

Answer 11

1. Humidification

2. Airway defence

Question 12

Why do we humidify air?

Answer 12

When we breath in, its not moist or as warm as we’d want

Question 13

Why is it better breathing through the nose than mouth?

Answer 13

• theres less turbulence and it has to travel less distance

- more air comes into contact with mucus so its better humidified

Question 14

What is the heat and moisture exchanger?

Answer 14

• part of the humidification of the air

- when dry air passes the fluid water evaporates into the gas mixture

Question 15

What mechanisms do we have in place to defend our airway?

Answer 15

• most particles we breath n stick to the mucus an we remove it e.g by coughing
• muco-ciliary escalator (mucus transport)

Question 16

What is expectoration?

Answer 16

Coughing

Question 17

Give 5 clinical features of cystic fibrosis?

Answer 17

• autosomal recessive inheritance
• abnormal cystic fibrosis transmembrane regulator protein (cftr)
• progressive lung infection and destruction
• affects all systems with epithelial surfaces

Question 18

What does the cftr protein do?

Answer 18

Protein on epithelial cells that control the airway lining fluid

Question 19

What are the two layers of airway lining fluid?

Answer 19

Periciliary and mucous

Question 20

Where are very large particles deposited? What is their mechanism of action? Give two examples

Answer 20

deposited - nose & pharynx
mechanism - intertial impaction
examples - pollen, sawdust

Question 21

Where are large particles deposited? What is their mechanism of action? Give an examples

Answer 21

deposited - large airway
mechanism - inertial impaction
examples - fungal spores

Question 22

Where are small particles deposited? What is their mechanism of action? Give two examples

Answer 22

deposited - bronchioles
mechanism - sedimentation
examples - particulate pollution, asbestos

Question 23

Where are very small particles deposited? What is their mechanism of action? Give two examples

Answer 23

deposited - exhaled
mechanism - diffusion
examples - smoke (including cigarette)

Question 24

Why are pollution particles so dangerous?

Answer 24

pollution particles can get as far as the bronchioles in the lung where the defence mechanisms are not as strong as its nearer the alveoli

Question 25

“the size of a particle determines where it is deposited”

where could this be useful?

Answer 25

in inhaled drug deposition e.g if you want the drug to be absorbed into the blood, it must be very small as it must be able to reach the alveolus

Question 26

What are the 3 non-immunological systems in place to remove pathogens?

Answer 26

1. Physical barrier and removal
2. Chemical inactivation (mucus produces chemicals)
   - lysozyme
   - protease enzymes e.g elastase (& anti-protease system)
   - antimicrobial peptides e.g human B defensives
3. Alveolar macrophages

Question 27

What are human B defensins?

Answer 27

Self antibiotics against certain bacteria in lungs

Question 28

What are the humoral immunological pulmonary defence systems in place?

Answer 28

Production of immunoglobulins:

• IgA (nose and large airway)
• IgG (small airway)
• IgE (allergic disease)

Question 29

Describe the cell mediated immunological pulmonary defence systems in place?

Answer 29

-epithelial cells
-macrophages
Pathology:
-neutrophils (infection)
-eosinphils (allergy)

Question 30

What conditions could be associated with air pollution?

Answer 30

• Asthma
• Pneumonia
• Stroke
• -Heart attack
• T2 diabetes