9. Lung Infection

Question 1

What are the defences of the lung?

Answer 1

Mechanical, local and systemic

Question 2

Give examples of mechanical defence?

Answer 2

Pathogens sticking to mucus or the epithelium acting as a barrier

Question 3

Give examples of local defences?

Answer 3

BALT - samples antigens and produces antibodies
Neutrophils - mobilise from the circulation
Antimicrobial substances in secretions

Question 4

What are the cilia surrounded by?

Answer 4

Periciliary fluid - watery

Question 5

What floats on top of the cilia?

Answer 5

Mucus - sticky gel like

Question 6

What is the rate at which cilium beats at?

Answer 6

15 times a second

Question 7

Describe the movement of the cilium?

Answer 7

The backwards and forwards movement is different. When moving forward the cilium engages the mucus when it is vertical. It is withdrawn in a curved fashion within the periciliary fluid back to the start

Question 8

What part of the cilia engages with the mucus?

Answer 8

Little claws

Question 9

What rhythm does the cilia beat in?

Answer 9

metachronal rhythm

Question 10

What is the arrangement of microtubules in cilium?

Answer 10

9+2 pattern with the 9 microtubules pairs on the outside with dynein arms

Question 11

What are the dynein arms for?

Answer 11

They have ATPase which provides energy to move the microtubules up and down each other. It makes the cilia bend

Question 12

What is the function of the central tubule?

Answer 12

It used as an axis to move against

Question 13

What can problems with the host defence systems be?

Answer 13

congenital or acquired

Question 14

What are the two most common acquired defects of the mucociliary system?

Answer 14

Cigarette smoking

Viral infection

Question 15

What cigarette smoke do to the mucociliary system?

Answer 15

It destroys the cilia - makes you more prone to infection. Tight junctions begin to fall apart

Question 16

How long does it take for cilia to regrow, restoring the mucociliary system?

Answer 16

6 weeks

Question 17

What are compound cilia?

Answer 17

Groups of cilia which are useless - no function. This occurs when cilia grows back abnormally

Question 18

What is the risk being infected by a virus?

Answer 18

It puts you at risk from a bacterial infection as well

Question 19

What could be the reason of an acute and overwhelming syndrome?

Answer 19

Very virulent bug or disorder of the host defence

Question 20

What could be the reason for recurrent-acute, slow to resolve syndrome?

Answer 20

Bronchial, pneumonic or abnormalities in host defence

Question 21

Define dextrocardia and what does it suggest?

Answer 21

It is an abnormality where the heart lies on the right side. Suggests some sort of ciliary abnormality

Question 22

People born with cilia that do not work have a heart on a random side of the body. Why?

Answer 22

This is because the microtubules are used to guide cells around during embryological development. So if the microtubules didn’t guide the cardiac cells to the right place then the cilia which are made up of microtubules won’t work.

Question 23

What structural defects will mean that the cilia doesn’t work?

Answer 23

1) No outer dynein arms

Dynein arm defects

Question 24

How do you identify defective cilia?

Answer 24

1) Biopsies - use a microscope to look at beating

2) Biochemical marker - look for reduced levels of NO

Question 25

What bacteria is the most common cause of bronchitis and sinusitis?

Answer 25

Haemophilus influenzae

Question 26

How do bacteria attach to the epithelial surface?

Answer 26

With hair like fimbriae which act as anchors. They then divide and form a colony

Question 27

How do bacteria avoid clearance from airways?

Answer 27

1) Exoproducts that impair mucociliary clearance - disorganise ciliary beat, damage epithelium 2) Enzymes - breakdown local immunoglobulins 3) Exoproducts - impair neutrophil, macrophage and lymphocyte function 4) Adherence - increased epithelial damage and tight junction separation 5) Avoid immune surveillance

Question 28

What is pneumonia?

Answer 28

Inflammatory condition of the lung affecting primarily the alveoli. The alveoli can be filled with pus

Question 29

List the clinical features of pneumonia

Answer 29

Cough, sputum, fever, dyspnoea, pleural pain, headache

Question 30

Why is there stabbing pleuritic chest pain in pneumonia?

Answer 30

When inflammation starts to affect the pain fibres on the surface of the lung

Question 31

What is the most common cause of bacterial pneumonia

Answer 31

Streptococcus pneumoniae

Question 32

How does streptococcus pneumonia cause inflammation?

Answer 32

Produces pneumolycin which punches holes in cells killing them. Has a negatively charged polysaccharide capsule which makes it more virulent

Question 33

Define gas trapping

Answer 33

Air trapped when airways have collapsed - results in high RV. This is caused by lost of elasticity in to the lungs

Question 34

What kind phlegm do people with bronchiectasis have?

Answer 34

Greeny phlegm

Question 35

What are typical bronchiectactic airways?

Answer 35

Damaged airways which have fallen apart and are much bigger than they should be

Question 36

What is bronchiectasis

Answer 36

Bronchiectasis is a disease in which there is permanent enlargement of parts of the airways of the lung

Question 37

How is excess phlegm removed in brochiectatic patients?

Answer 37

physiotheraphy

Question 38

What does the removal of phlegm help with?

Answer 38

Reduction of inflammation because then the neutrophils dont have a stimulus to move in

Question 39

List the causes of chronic bronchial sepsis?

Answer 39

1) Congenital 2) Mechanical obstruction 3) Inflammatory pneumonitis 4) Fibrosis 5) Postinfective 6) Immunological 7) Imparied mucocillary clearance 8) Immune deficiency

Question 40

What is the cycle of chronic inflammation

Answer 40

Microbial infection -> inflammation -> tissue damage -> Impaired lung defences -> More infection = more inflammation

Question 41

What is damage caused by inflammation based upon?

Answer 41

Protease anti-protease balance

Question 42

Give an example of an anti-protease?

Answer 42

Alpha 1 antitrypsin

Question 43

What is function of an anti-protease?

Answer 43

They neutralise proteases preventing damage to the body

Question 44

Describe what happens in chronic inflammation in terms of proteases and anti-proteases?

Answer 44

In chronic inflammation there are so many neutrophils so much protease is released that it overwhelms the anti-proteases. The free proteases then cause damage

Question 45

What effect does protease have on the epithelium?

Answer 45

It breaks down the epithelial surface causing damage

Question 46

What are the risks of have damaged areas of epithelium?

Answer 46

They become more susceptible to infection

Question 47

How does bronchiectasis affect the bronchial wall?

Answer 47

Patients with bronchiectasis have chronic inflammation resulting in high levels of neutrophils which digest the elastin

Question 48

What could be the reason for daily purulent sputum only temporarily responding to antibiotic?

Answer 48

Abnormality in host defenses

Question 49

What are the common complaints for patients with bronchiectasis?

Answer 49

Daily sputum production Recurrent respiratory infections Breathlessness Fatigue