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Respiratory > Asthma > Flashcards

Asthma Flashcards

1
Q

What are the three main characteristics of asthma?

A
  • reversible airflow limitation
  • airway hyper-responsiveness
  • bronchial inflammation
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2
Q

Asthma aiway changes

A
  • hypertrophy (increased mass of smooth muscle)
  • oedema (accumulation of interstital fluid)
  • Increased mucus secretion
  • Epithelial damage
  • Sub-epithelial fibrosis
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3
Q

What does the term ‘Atopy’ mean?

A
  • genetic tendency to develop allergic tendancies, such as asthma, ezcema
  • increased IgE levels
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4
Q

What are the causes and triggers of asthma?

A
  • genetics (production of cytokines)
  • environmental exposure to allergens
  • viral infections
  • cold air
  • emotion
  • drugs (NSAIDs - asprin)
  • exercise
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5
Q

What is chronic asthma?

A

Pathological changes to the bronchioles –> long standing inflammation

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6
Q

What is an immediate asthmatic reaction?

A
  • airflow limtation begins within minutes of contact with the allergen
  • reaches maximum within 15-20mins
  • subsided within an hour
  • type I hypersensitivity reaction
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7
Q

What is dual and late-phase reactions, in asthma?

A
  • Following an immediate reaction, asthmatics may have a prologed airflow limitation (responds less to bronchodilators)
  • Symptoms persist after allergen is removed
  • type IV hypersensitivity reaction
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8
Q

What is the main cell that drives airway inflammation?

A
  • Th2-type T lymphocytes
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9
Q

What is the main cell that drives airway tissue damage?

A
  • Th1 TNF-alpha
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10
Q

What cells are involved in inflammation?

A
  • Mast cells
  • Eosinophils
  • Dendritic cells
  • Lymphocytes
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11
Q

Explain mast cells during a reaction?

A
  • Mast cell numbers are increased within the epithelium smooth muscles and mucous glands
  • Release mediators –> histamine
  • Acts on smooth muscles, small blood vessels, mucus-secreting cells and sensory nerves
  • Release cytokines, chemokines and growth factors
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12
Q

Explain Eosinophils during a reaction?

A
  • Found in large numbers at bronchial wall
  • attracted to airways by cytokines (IL-3, IL-5)
  • Release LTC4 –> toxic to epithelial cells
  • Decreased effect by corticosteroids
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13
Q

Explain Dendritic cells and lymphocytes during a reaction?

A
  • Th2 pattern of cytokine expression
  • T-helper lympocytes activate mast cells, and eosinophils,
  • Th1 cells more prominant in severe cases
  • Th2 cells more prominant in less severe cases
  • influenced by corticosteroids
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14
Q

Explain the remodling of epithlium in asthma

A
  • loss of ciliated columnar cells

- More vulnerable to infection

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15
Q

Explain the remodling of epithlial basement membrane

A
  • thickened basement membrane

- collagen deposition

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16
Q

Explain the remodling of smooth muscle

A
  • hyperplasia

- actin and myosin cross links change –> increased contraction and stays contracted for longer

17
Q

Clinical features of asthma

A
  • wheezing
  • shortness of breath
  • worst at night
  • cough
18
Q

Atopic Vs Non-atopic

A

Atopic - extrinsic (environmental trigger) - IgE produced

Non-atopic- intrinsic - Inflammation

19
Q

What T cell is assoiciated with asthma?

A

Th-2 cell

20
Q

Explain the process of plasma cell production from antigen presentation

A 
Antigen presentation
Binds to CD4+ T cell
Proliferates --> Th0
Proliferates --> Th1 and Th2
Th2 --> binds to B cell by IL-4 --> Plasma cell
IgE secreted
21
Q

IL-5 released from Th2 does what?

A

Recruits eosinophils

22
Q

IL-13 and IL-4 from Th2 does what?

A

Mast cells express IgE receptors

23
Q

Once the antigen binds to IgE receptor on mast cell what happens?

A
  • stimulation of Ca+ into mast cells
  • release of Ca2+ from storage
  • release of histamine
24
Q

Stimulation of the postganglionic cholinergic fibres causes what?

A
  • bronchial smooth muscle contraction mediated by M3 muscarinic ACh receptors on ASM cells
  • increased mucus secretion mediated by M3 muscarinic ACh receptors on gland (goblet) cells
25
Q

Stimulation of the postganglionic noncholinergic fibres causes what?

A
  • bronchial smooth muscle relaxation mediated by nitric oxide (NO) and vasoactive intestinal peptide (VIP)
26
Q

Investigations into asthma

A
  • Lung function tests (PEFR)
  • diurnal PEFR
  • Spirometry (FEV1)
  • Exercise test
  • Trial of corticosteriods
27
Q

Management of asthma

A
  • abolish symptoms

- restore normal lung function

28
Q

Why are most asthmatic drugs given by aerosol?

A
  • bypass the liver for metabolism
29
Q

Drug treatment of asthma

A
  • SABA (Salbutamol)
  • ICS (Beclometasone dipropionate)
  • LABA (Salmeterol or formoterol)
  • ? LAMA - ipratropium
  • ?steroids - methotrexate
30
Q

What is an asthmatics FEV1/FVC ratio?

A
  • <75%

- obstructive pattern

Respiratory (25 decks)

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