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BIOM30002 - M2M > Lecture 10 - CF: Respiratory System > Flashcards

Lecture 10 - CF: Respiratory System Flashcards

1
Q

Describe the anatomy of the respiratory system

A 
Series of branching tubes:
• Upper airways
• Trachea
• Bronchi
• Bronchioles
• Terminal bronchioles
• Respiratory bronchioles
• Alveolar ducts
• Alveoli
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2
Q

What is the difference between the conducting and respiratory zones?

A

Conducting: mucosa lined, no gas exchange
Respiratory: simple squamous epithelium for gas exchange

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3
Q

What are the phases of lung development?

A
  1. Embryonic: lung bud appears, out pouching from foregut
  2. Pseudoglandular: branching of airways up to terminal bronchioles
  3. Canalicular: development of acinar region & type I and II pneumocytes
  4. Sacular / alveolar:
    • sacules form into alveolar ducts
    • decrease in interstitial tissue, septation
    • alveoli start to develop
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4
Q

What is the tissue origin of the lungs?

A

Endoderm

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5
Q

What is the acinus?

Of what is it composed?

A

This is the gas exchange region of the lung

Composed of:
• respiratory bronchioles
• alveolar ducts
• alveolar sacs
• alveoli
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6
Q

What is septation?

A

Septa form between alveoli to form more alveoli

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7
Q

What are some functions of the lungs?

A
  • Gas exchange
  • Defence
  • Acid-base balance
  • Metabolic
  • Heat exchange
  • Water balance
  • Phonation
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8
Q

What are the defences in the lung?

A 
Upper:
• cough reflex
• sneezing
• mucociliary escalator
• turbinates, filter
Lower:
• surfactant
• IgA
• complement
• alveolar macrophages
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9
Q

What is ASL and what is it composed of?

A

Airway surface liquid:
• periciliary layer
• mucous gel layer

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10
Q

Describe the function of the mucociliary escalator

A

ASL present on cells in lumen

Cilia on apical surface beat 12-15 times per second

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11
Q

Describe gas exchange in the lungs

A
  • Takes place at the level of alveoli
  • Alveoli filled with air upon inspiration
  • Gas diffuses in solution across the single celled wall of the alveolus into the capillary
  • Basement membrane between alveolus and capillary
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12
Q

What is the measurement of ‘Flow’

A

Volume / time (of air)

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13
Q

Which parameters do we measure to determine lung function?

A
  • Volume
  • Flow
  • Pressure
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14
Q

What are the various lung volumes and capacities of the lungs?

A 
Total lung capacity
Vital capacity
Tidal volume
Residual volume
Expiratory reserve volume
Inspiratory reserve volume
Inspiratory capacity
Expiratory capacity
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15
Q

Describe how FEV and FVC are measured

A
  1. Maximal inspiration
  2. Forced expiration until residual volume
    First second: FEV
    Until residual volume: FVC
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16
Q

When is most of the air exhaled when performing Spirometry?

A

First second

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17
Q

What happens with reversible intrathoracic airway obstruction?

A

Air can’t be exhaled as quickly

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18
Q

What are some pulmonary complications of CF?

A
  • Poor lung function, progressive decline
  • Cough and sputum production
  • Dyspnoea
  • Need for transplantation; death
  • Respiratory failure
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19
Q

What causes lung disease in CF?

A

The CFTR mutation(s)

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20
Q

Which cells in the respiratory system express CFTR?

A 
Epithelium of respiratory tract
Alveolar macrophages
Serous cells of submucosal cells
Type II pneumocytes
Neutrophils
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21
Q

What is the role of CFTR in the epithelium of the respiratory tract?
Describe what happens to this process in CF

A

Modulates the composition of ASL

  1. Cl- secretion through CFTR
  2. Na+ and H20 absorption through ENaC

In CF:

  1. No Cl- secretion
  2. No ENaC inhibition; increased Na+ and H2O absorption
  3. Decrease in ASL volume
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22
Q

What are the sequalae of reduced ASL volume?

A
  • Reduced ciliary beating in periciliary layer
  • Decreased lubrication, adherence of mucous plaque

→ Promotes chronic infection

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23
Q

Discuss the interaction between CFTR and Bicarbonate ions

A

CFTR important for bicarbonate ion transport

Mutation leads to:
→ improper pH regulation of ASL (airway surface liquid)
→ inhibits antimicrobial function

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24
Q

What are the thick mucous plaques in the airways of CF patients?

A

Adhere to airway epithelial surface

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25
Q

Describe the anaerobic milieu

A

Increased oxygen consumption of epithelial cells
→ anaerobic environment

This anaerobic environment is ideal for the growth of bacteria
→ Pseudomonas aeruginosa converts to anaerobic biofilm mode of growth

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26
Q

What is the common feature of lung inflammation in individuals with CF?
Describe the effect of this

A

Presence of great n°’s of neutrophils, causing:
• tissue damage
• neutrophils possess large amount of oxidants and proteases that damage tissue when the cells are present in too large numbers (regurgitation, etc.)

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27
Q

Why are the lungs of individuals w/ CF under such great oxidative stress?
What is the effect of this?

A

Oxygen radicals from:
• air
• bacteria
• host immune response

Leads to:
• pulmonary deterioration
• bronchiectasis
• oxidation of airway proteins
• inflammation
28
Q

What is bronchiectasis?

A

Dilation of part of bronchial tree, caused by muscle and elastic tissue damage

29
Q

What causes the release of large amounts of pro-inflammatory cytokines in the lungs?

A

Epithelial innate and apative immune cells constantly triggered by:
• infectious agents
• ROS
• proteases

30
Q

What is the role of NF-κB in CF?

A

(Nuclear factor - κB)
Transcription factor, which is dysregulated in CF
Respiratory epithelium is increasingly pro-inflammatory

31
Q

What is ceramide, and where is it found?

What is its role in CF?

A

• Ceramide is a breakdown product of Sphingomyelin
Found in:
• plasma membrane
• endosomal compartments

Role in CF:

  1. Triggers apoptosis & pulmonary inflammation
  2. Deposition of DNA from apoptotic cells
32
Q

What are the triggers of inflammation in the airways in CF?

A
  • Sphingomyelin
  • CFTR dysfunction
  • Unfolded CFTR
  • TLR signalling (from microbes)
33
Q

Describe the role of pulmonary inflammation in CF and pathogens

A

The pulmonary inflammation may facilitate pathogenesis of organisms:
e.g.
• Pseudomonas stimulates lipid raft formation
• Lipid rafts contain CFTR and cave-in-1
• Lipid rafts stimulate uptake of the bacterium into epithelial cells

34
Q

Describe the vicious cycle of pulmonary dysfunction in CF

A
  • Mutation in CFTR gene → viscous mucous
  • Viscous mucous → airway obstruction & predisposes infection
  • Infection → inflammation
  • Inflammation → favours thick mucous production

And the cycle continues…

35
Q

What can infection, obstruction and inflammation of the airways lead to?

A

Bronchiectasis
(dilation & damage of bronchi)
• neutrophilic inflammation in and around bronchi
• enlargement of lungs

36
Q

Which infectious agents are individuals with CF particularly susceptible to?

A
  • Pseudomonas
  • S. aureus
  • Haemophilus influenza
  • Mycobacteria
37
Q

Describe what happens to lung function over the years in individuals with CF

A
  • Slow decrease in lung function
  • Measured as decreased FEV1

NB better outcomes now, as compared to 20 years ago

38
Q

When does the lung bud first appear during development?

A

Day 26-28

39
Q

What is being referred to when people say: ‘lung function is 80%’?

A

FEV1

40
Q

What is the normal effect of CFTR on ENaC in the lungs?

A

Normally inhibits ENaC, reducing the Na+ that can come into the epithelial cells

41
Q

What are the two important antioxidants?

A

Glutathione

Thiocyanate

42
Q

Discuss the interaction between CFTR and antioxidants

A

CFTR important in Glutathione and Thiocyanate maintenance in epithelial fluid lining

With CFTR mutation, we see increased:
• oxidative stress
• lung inflammation

43
Q

Which bacteria commonly infect the CF lung?

A
  • P. aeruginosa
  • S. aureus
  • H. influenzae
44
Q

What is bad about P. aeruginosa infection in the body?

A

They form biofilms
Makes it hard for the immune system to clear
Resistant to antibiotics

45
Q

Is CF obstructive or restrictive?

A

Obstructive

46
Q

What happens to FEV1 in CF?

A

Decreased: not as much volume can be exhaled in the first second as predicted

47
Q

When performing spirometry, does it take longer or shorter for a person w/ CF to empty their lungs?

A

Longer

48
Q

What is the tissue origin of the lungs?

A

Endoderm

Out-pouching of the primitive foregut

49
Q

When is the embryonic phase?

A

0-6 weeks

50
Q

When does the epithelium of the lungs thin?

A

Canalicular

51
Q

When does septation occur?

A

Alveoar / sacular

52
Q

When do the lungs start to resemble the lungs in babies and adults?

A

Pseudoglandular

53
Q

When do the pneumocytes start to thin?

A

Canalicular

54
Q

When does the acinar region develop?

A

Canalicular

55
Q

When is the pseudo glandular phase?

A

6-16 weeks

56
Q

When is the sacular phase?

What is this also called?

A

26-36 weeks

Alveolar

57
Q

When do the pneumocytes form?

A

Canalicular

58
Q 
Describe the connections between the following terms:
 • respiratory bronchiole
 • alveolar duct
 • alveoli
 • alveolar sac
A

Alveolar ducts are tiny ducts that connect the respiratory bronchioles to alveolar sacs, each of which contains a bunch of alveoli (the balls)

59
Q

When do the alveoli start to develop?

A

Sacular / alveolar

60
Q

When is there a decrease in interstitial tissue in development?

A

Sacular / alveolar

61
Q

When is the canalicular phase?

A

16-26 weeks

62
Q

How many alveoli in a baby?

A

1/3rd of the number present in adults

i.e. 100 million

63
Q

Compare the surface area of the respiratory surface of the lung in babies and adults

A

Babies: 4 m squared
Adults: 10 m squared

64
Q

What happens in the post-natal phase?

When is this?

A

Birth to unknown

Lungs continue to develop after birth, but it is unclear when it finished (at least into the teenage years)

65
Q

List all the ways that CFTR mutation can disrupt lung function

A
  1. Dysregulated Cl- and Na+ transport
  2. Dysregulated Bicarbonate transport
  3. Dysregulated antioxidants
  4. Pro-inflammatory nature of CF epithelium
  5. Protein accumulation
  6. Anaerobic milieu
  7. Oxidative stress
  8. Neutrophilic inflammation

BIOM30002 - M2M (36 decks)

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