Pulmonary Defence Mechanisms

Question 1

How much air does one inhale every day?

Answer 1

8000L

Question 2

What are the two main reasons there isn’t a great defence mechanism against pathogens?

Answer 2

The lungs need fast movement of air into circulation (not much filtering possible) and efficient gas exchange (requires moist surfaces, which is where microorganisms also thrive)

Question 3

What are the three classes of stuff in the air?

Answer 3

Large particulates
Fine pollution material
Microscopic pathogen

Question 4

Give examples of large particulates

Answer 4

Foreign body aspiration (food, liquid, choke hazards)

Question 5

Give examples of fine particulate material and their sizes

Answer 5

Pollution (<2.5-1000um)
Dust (0.1-1000um)
Pollen (10-100um)

Question 6

Give examples of microscopic pathogens and their sizes

Answer 6

Fungal spores (2-10um)
Bacteria (0.5-5um)
Viruses (less than 1um)

Question 7

What does particle size have to do with where it gets stuck in the respiratory tree?

Answer 7

The bigger the particle, the earlier it will get deposited in the respiratory tree

Question 8

What are the three types of respiratory immunological defence mechanisms?

Answer 8

Physical obstructions
Protective reflexes
Immunological defence system

Question 9

What are the two types of physical obstructions in the respiratory systems?

Answer 9

Macro and micro

Question 10

Give examples of macro obstructions and how they work

Answer 10

Nasal hairs, conchae, branching airways

Helps to filter air and prevent particles from reaching the airways

Question 11

Give examples of micro obstructions and how they work

Answer 11

Cilia, mucus

Trap and remove particles and microorganisms- also goblet cells which is where the mucous is secreted from

Question 12

Give examples of the protective reflexes

Answer 12

Coughing
Sneezing
Expiratory reflex

Question 13

Give examples of immunological defence mechanisms in the lungs

Answer 13

Lung resident immune cells (alveolar macrophages)
Structural cells (epithelial cells/innate immunity)
Antimicrobial proteins

Question 14

How do cillia move the mucus in one direction?

Answer 14

On the reverse stroke they curl up so they only move in the pericillary layer

Question 15

What is the pericillary layer?

Answer 15

Layer under mucus that is more watery

Question 16

How does cystic fibrosis affect the lungs?

Answer 16

The mutation dehydrates the mucus, so decrease in airway surface fluid

• > cillia dysfunction
• > decreased mucus clearance

Question 17

How does tobacco smoke exposure affect the mucocilliary function?

Answer 17

Smoke inflames the airways

• > goblet cell hyperplasia and cillia damage
• > mucus hypersecretion and decreased mucus clearance

Question 18

What can loss of mucocillary function lead to?

Answer 18

Lung infections and airway pathology

Question 19

How do you cough?

Answer 19

Stimulation of mechano or chemoreceptors

• > afferent impulses to cough centre (medulla)
• > efferent impulses via parasympathetic and motor nerves to diaphragm, intercostal muscles and lung
• > increased contraction of diaphragmatic, abdominal and intercostal muscles

Question 20

How does the branched structure of airways help to filter particles?

Answer 20

When branching occurs, airflow becomes turbulent and means pathogens are more likely to come into contact with the mucosal surfaces

Question 21

Give three examples of things alveolar macrophages cant digest

Answer 21

Silicone
Asbestosis
Pneumonicosis

Question 22

How do structural cells help to detect pathogens in the lungs and alert the immune system?

Answer 22

Specific receptors which pick up on specific surface proteins, which cause cytokine release and leukocyte migration and activation

Question 23

What happens to the airway/lung microbiota in different respiratory diseases?

Answer 23

Different pathogens are out of balance