Resp 9 - Lung Infection

Question 1

There are 3 levels of defence in the respiratory tract. Mechanical, Local and Systemic. Give an example of each

Answer 1

Mechanical - mucociliary clearance

Local - BALT. Immune system within Respiratory tract. Antimicrobial substances too.

Question 2

Ciliated epithelia line the airways upto respiratory bronchioles. How are they knitted together?

Answer 2

By tight junctions.

Made up of ciliated cells and goblet cells.

Question 3

What are the 2 layers in the respiratory tract?

Answer 3

Mucus layer on top which is sticky.

Periciliary fluid which is watery.

Question 4

Each cilium beats around 15 times per second. What happens when cilia reach the bottom of the forward stroke?

Answer 4

The cilium is withdrawn in a curved fashion (drawn within the periciliary fluid).

Question 5

The cilia beat to a metachronal rhythm. What other adaptation do they have to engage with mucus?

Answer 5

They have claws on their tips.

Question 6

Describe the ultrastructure of a cilium.

Answer 6

9+2 pattern.

9 MT pairs on outside with dynein arms (containing ATPase - provides energy for MTs to move up and down)

Question 7

Problems with host defence can be congenital or acquired. What are the 2 most common acquired defects of the mucociliary system?

Answer 7

1. Cigarette smoking - destroys cilia

2. Viral infection

Question 8

Tight junctions in cilia is how damage can be done to cilia.

Answer 8

T, tight junctions fall apart

Question 9

What causes yellow-green secretions?

Answer 9

Bacterial infection present.

After bacterial infection, cilia must regrow. (disabled for about 6 weeks while regrowing) - cilia may grow back abnormally

Question 10

Compound cilia?

Answer 10

Two cilia joined together - they are useless as they don’t know how to function

Question 11

3 types of respiratory infection syndrome (disordered disorders).

Answer 11

1. Acute, overwhelming. Maybe due to very virulent bug or disorder of host defence.
2. Recurrent acute, slow to resolve (with or without AB). Could be Bronchial or Pneumonic. Host defence abnormalities present in people with recurrent acute illnesses.
3. Daily purulent sputum - only temporarily responding to AB.

Question 12

What causes dextrocardia and what is unique about it?

Answer 12

Caused by ciliary abnormality.

Cilia doesn’t work - side of the body that the heart is on is random. MTs needed to guide cells during embryological development.

Question 13

Give an example of a dynein arm defect?

Answer 13

Inner arm present but no outer arm.

Question 14

What is a biochemical marker for people with malfunctioning cilia?

Answer 14

They don’t have as much NO production as normal people.

Difference in nasal NO or people with Primary Ciliary Dyskinesia compared to those without

Question 15

What is the most common cause of bronchitis and sinusitis?

Answer 15

Haemophilus influenzae - have fimbriae to attach onto epithelia. Then divides and forms colony.

Bacteria stick down to DAMAGED epithelium - not where there is cilia

Question 16

5 ways in which bacteria avoid clearance from airways

Answer 16

1. Exoproducts impair ciliary clearance - impair ciliary beat, etc
2. Enzymes - local IG breakdown
3. Exoproducts - impair neutrophil, macrophage and lymphocyte function
4. Adherence - increased by epithelial damage
5. Avoid immune surveillance - (e.g. surface heterogeneity etc)

Question 17

What can pneumonia cause?

Answer 17

Stabbing pleuritic chest pain - due to pain fibres on lung surface

Question 18

Describe streptococcus pneumonia

Answer 18

1. Has polysaccharide capsule
2. Negatively charged capsule means hard for bug to bind to epithelium but also much more virulent.
3. Produces pneumolycin which punches holes in cells and kills them

Question 19

What is gas trapping?

Answer 19

When you breathe out, diseased lungs have lost elasticity and the airways close down and air gets trapped. Which is why people with diseased lungs have a greater RV.

Question 20

Lots of greeny phlegm. Airway structure damaged and is much bigger. What is it?

Answer 20

Bronchiectasis.

Question 21

How can fungus cause bronchiectasis?

Answer 21

Aspergillus fumigatus.
Lots of eosinophils.
Strong allergic reaction can cause allergic bronchopulmonary aspergillosis. This damages airways causing bronchiectasis.

Question 22

What is the vicious cycle of infection and inflammation?

Answer 22

Microbial infection - inflammation - tissue damage - impaired lung defences

Question 23

How does the protease-antiprotease balance affect damage caused?

Answer 23

When so much protease is released by the vast number of neutrophils that the protease overwhelms the antiprotease - free proteases then present in secretions which causes damage.

Question 24

What is the most common anti protease?

Answer 24

Alpha 1 antitrypsin

Question 25

Patients with bronchiectasis have chronic inflammation for years. What effect can this have on elastin?

Answer 25

Elastin goes