L3 Lung structure and airway disease Flashcards

1
Q

The respiratory system includes: (list)

A
  • Lungs
  • Airways
  • Blood vessels
  • Gas exchange
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2
Q

3 main divisions of the respiratory tract

A
  • Conducting airways
  • Resistance airways
  • Respiratory Airways
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3
Q

Whats part of the conducting airway

A
  • Trachea
  • Primary bronchus
  • Secondary bronchus
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4
Q

Whats part of the resistance airway?

A
  • Bronchiole (<=1mm)
  • Terminal Bronchiole
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5
Q

Whats part of the Respiratory airway?

A
  • Alveolar duct
  • Alveolar sac
  • Respiratory Bronchiole
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6
Q

(cartilage) Bronchus divides to

A

Bronchiole (no catilage)

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7
Q

Bronchus and Bronchiole contain

A
  • Glands (mucus)
  • Smooth muscle epithelium
  • Cartilage
  • Connective tissue and elastic fibre
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8
Q

Alveolar airways contain

A
  • Respiratory bronchiole
  • Smooth muscle
  • alveolar duct
  • Alveolar sac
  • Arteriole
  • Alveoli
  • Interalveolar septum
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9
Q

Route of blood in the alveolar cappillary

A

O2 in lumen

Surfactant

Aairway epithelium fused basil lamina vascular epithelium

Capillary

Binds to haemoglobin

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10
Q

Distance O2 travels in capillary

A

0.2-0.6µm

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11
Q

Pulmonary arteries carry blood where?

A

To the lungs

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12
Q

Pulmonary veins carry blood where?

A

From the lungs

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13
Q

Pulmonary veins carries what?

A

Oxygen (O2)

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14
Q

Pulmonary arteries carry what?

A

Carbon Dioxide (CO2)

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15
Q

Bronchial arteries do what to blood and where

A
  1. supply
  2. trachea, bronchi, bronchial branches, esophagus, and visceral pleura
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16
Q

Bronchial veins do what to blood and where

A
  1. Drain from airways
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17
Q

Bronchial veins carry what in blood

A

Carbon Dioxide (CO2)

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18
Q

Bronchial arteries carry what in blood?

A

Oxygen (O2)

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19
Q

Airway epithelium type

A

Pseudostratified columnar

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20
Q

What does airway epithelium do?

A
  • Physical barrier
  • Housekeeping
  • Catabolic and anabolic metabolism
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21
Q

Airway epithelium

Physical barrier

A
  • inhibits penetration of inhaled noxious substances
  • allergens, mast cell-derived mediators, particulate
    matter, irritant molecules
    – prevents access to submucosa
  • nerves, vascular tissue, airway smooth muscle
22
Q

Airway epithelium

Housekeeping role

A

– cilia beat synchronously, propel mucus towards throat
– mucus and particulate matter continually cleared
– ciliated cells damaged first in asthma

23
Q

Airway epithelium

Catabolic metabolism

A
  • Active
  • via cytochrome P450 system
  • peptide degradation via neutral endopeptidase
  • > neuropeptised are degraded and are proteins with airway activity.
  • – protects sensitive targets - nerves, muscle, glands
24
Q

Airway epithelium

Anabolic metabolism

A

– synthesis of inhibitory mediators – PGE2 (relaxes airway muscle)
– rich source of peptides – endothelin (growth factor)
– produces pro-inflammatory cytokines

25
Q

Airway nerves
excitatory and inhibitory

A

Contraction and relaxation

26
Q

Airway nerves

Cholinergic

A
  • Excitatory
  • Releases ACh
  • Dom neiral pathway
  • Role in regulating airway smooth muscle tone and mucus production
27
Q

Airway nerves

Noradrenergic

A
  • Inhibitory
  • Relaxation
  • Noradrenaline decreases smooth muscle tone
  • no major role in main bronchi
28
Q

Airway nerves

Inhibitory nonadrenergic noncholinergic (iNANC)

A

– release nitric oxide (NO)
– innervates smooth muscle directly
– relaxation

29
Q

Airway Nerves

Excitatory nonadrenergic noncholinergic (eNANC)

A

– release neuropeptides e.g., substance P, neurokinin A – increase airway tone, secretion of mucus and microvascular
leakage
– capsaicin in pepper spray

30
Q

What is asthma?

A

Chronic inflammatory disease of the airways
characterised by bronchial obstruction and airflow limitation.

31
Q

What characteristic in asthma are reversible

A

Bronchial obstruction and airflow limitation.
Either spontaneously or with treatment

32
Q

Asthma characteristics/symp

A

– shortness of breath, wheeze, tight chest, cough
– allergic, occupational, exercise-induced, aspirin
– mild, moderate, severe

33
Q

Allegeric response in asthma [Early phase]

A
  • Decrease in Forced expiratory vol in 1 second (FEV1), peak at 30-40 min, resolves in 2-3 hrs
  • mast cell-derived histamine and leukotrienes (by the decrease if FEV1)
  • Contract
34
Q

Allegeric response in asthma [Late phase]

A
  • release of inflammatory mediators cause submucosal oedema, airway wall swelling, secretion of mucus
  • epithelium remodelling, airway muscle
    hypertrophy/hyperplasia, subepithelial fibrosis
35
Q

Submucosal oedema

A

Leaking of plasma from microvessels of bronchiole circulation that allows airway to swell.

36
Q

Bronchial Obstruction in Asthma

A

– ↑ airway smooth muscle tone
– ↑ secretion of mucus
– shedding of the epithelium and accumulation of debris in airway lumen
– oedema and swelling of the submucosa
– airway smooth muscle hypertrophy (↑ cell size) and hyperplasia ↑ cell number)
– sub-epithelial fibrosis

37
Q

What are asthmaics hyperrespovsice to

A

– methacholine, histamine, cold air
– allergic late phase response, respiratory viruses

38
Q

Airway resistance

A

– resistance to airflow is inversely proportional to the radius of the lumen raised to the fourth power
* R 1/inverse r4

39
Q

Airway narrowing

A

– ↑ airway smooth muscle force and/or mass
– microvascular leakage from post-capillary venules and resultant oedema

40
Q

Histamine and asthma

A
  • Stored in mast cells and basophils
    – released in response to appropriate allergen
    – early phase response
  • Bronchoconstriction, airway wall oedema
    – bronchial obstruction and airflow limitation
41
Q
  • Histamine (H1) receptor antagonists (antihistamines) asthma
A

– seasonal allergies e.g., hay fever
– not useful in asthma

42
Q
  • Histamine (H4) receptor antagonists in development in asthma
A

– asthma, atopic dermatitis, psoriasis

43
Q

Leukotrienes asthma mediator

A
  • Family of lipid mediators derived from arachidonic acid metabolism
  • Released in response to allergen exposure
    – early and late phase response
  • LTB4 family is a chemoattractant for inflammatory cells
  • LTd,e,c4
    • Bronchoconstrictors, mucus secretion↑, incude mediator from inflammatory cells
44
Q

Chronic Obstructive Pulmonary Disease (COPD)

A
  • Progressive degenerative disease causes death
    – debilitating symptoms, shortens lifespan
    – primary causes – tobacco smoking and air pollution
  • most important therapy is smoking cessation
  • indoor air pollution – heating + cooking
  • outdoor air pollution
  • occupational dusts, chemicals, vapours, irritants,
    fumes
45
Q
A
46
Q
  • COPD =
A

chronic bronchitis + emphysema

47
Q

Combination Bronchodilator –
Treatment of COPD

A

Ipratropium bromide (muscarinic antagonist)
+ salbutamol (b2-adrenoceptor agonist)

48
Q

Triple Combination Therapy –
Treatment of COPD

A

Glucocorticoid +
Muscarinic Receptor Antagonist
+ Long Acting b2-Agonist

49
Q

Chronic Bronchitis Features

A
  • Inflammatory disease with irreversible airflow limitation
  • Hypersecretion of bronchial mucus
    – hypertrophy & hyperplasia of bronchial mucus-secreting cells
    – chronic cough, excessive sputum
  • Secondary respiratory infections
    – excessive mucus production
50
Q

Chronic Bronchitis Treatment

* Selective phosphodiesterase IV inhibitor (roflumilast)

A

– improves lung function
– ↓ frequency of exacerbations
– targets underlying inflammation

50
Q

Chronic Bronchitis Treatment

Drugs provide symptom relief

A
  • b2-adrenoceptor agonists
    – muscarinic antagonists
    – glucocorticoids
    – mucokinetic drugs ( mucus viscosity)
    – antibiotics (secondary infections)
51
Q

Emphysema

A
  • Degenerative, peripheral lung disease
  • Involves destruction of alveolar membranes
    – causes severe impairment of:
  • oxygen delivery
  • carbon dioxide clearance
  • Often associated with smoking and chronic bronchitis