Host defence in the Lung: Non-immune mechanisms

Question 1

Host defence functions: 3 types

Answer 1

Intrinsic: Always present (apoptosis, autophagy, RNA silencing, antiviral proteins)

Innate defence: Induced by infection (Interferon, cytokines, macrophages, NK cells

Adaptive immunity: Tailored to a pathogen (T cell, B cells)

Question 2

What are some of the chemicals secreted by respiratory epithelium to play a role in host defence?

Answer 2

antiproteinases
anti-fungal peptides
anti-microbial peptides
Antiviral proteins
Opsins

Question 3

Airway mucus: what does it contain? what produces it? what’s its purpose?

Answer 3

Airway mucus is a viscoelastic gel containing water, carbohydrates, proteins, and lipids.

It is the secretory product of the mucous cells (the goblet cells of the airway surface epithelium and the submucosal glands).

Mucus protects the epithelium from foreign material and from fluid loss

Question 4

Mucus clearance- How is it removed?

Answer 4

Cilia beat in directional waves to move the mucus up the airways. Mucus is transported from the lower respiratory tract into the pharynx by air flow and mucociliary clearance.

Question 5

What are the 3 causes of a cough? giving examples dor each

Answer 5

1. irritant - smoke, fumes, dust
2. diseases conditions e.g. COPD, tumors etc.
3. Infections (influenza)

Question 6

What is a sneeze and what causes a sneeze?

Answer 6

involuntary expulsion of air containing irritant from nose

1. irritant of nasal mucosa
2. excess fluid in airway

Question 7

process of complete repair in respiratory epithelium?

Answer 7

complete repair of airway epithelium- injury causing ‘hole’ in airway, cells spread and dedifferentiate, cell migration, cell proliferation, rediffernetiation and regeneration

Question 8

what is functional plasticity?

Answer 8

exists in multiple cells, lots of the respiratory epithelium cells can tur into others e.g. basal into club, ATll to ATI

Question 9

What happens following insult/injury to the airway epithelium?

Answer 9

The cells exert plasticity, leading to a complete repair

Question 10

what could happen if process of respiratory complete repair goes wrong? an example of this?

Answer 10

creates an obstructive lesion leading to obstructive lung disease

An example of goblet cell metaplasia in the airway of a heavy smoker

Question 11

What is a Mucus plug and when may it occur?

Answer 11

Associated with severe disease and are mucus and inflammatory cells blocking the airways. Hence the term obstructive lung disease is sometimes used

Question 12

How do we normally get pulmonary diseases?

Answer 12

When there is an abnormal response to insult/injury, leading to an incomplete repair to the resp. epithelium