When things go wrong in the respiratory system Flashcards by Miayla Marcus

What do you use to measure airway resistance?

Forced expiratory volume in 1 sec (FEV1) by spirometry

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What is FEV1 usually?

FEV1 is normally 80% of vital capacity (forced exhalation is usually about 80% of total exhalation)

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What are the main features of Chronic Obstructive Pulmonary diseases (COPDs)?

Narrowing of airways -> increased airway resistance
Elastic recoil of lungs lost -> decreased outflow pressure
Both lead to decreased FEV1
Increased residual volume (RV) (air remaining in lungs after fully exhaled) -> appearance of chest over-inflation

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What are the main COPD diseases?

Chronic bronchitis – narrowing

- Emphysema – recoil

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What is Chronic Bronchitis, how do you define it and what is it usually due to?

Inflammation of the bronchi – mucus hypersecretion
Due to: smoking (80%), environmental irritants
Lasts: at least 3 consecutive months in 2 consecutive years

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What happens in Chronic Bronchitis?

Irritants cause inflammation in bronchi
Abnormal mucus secretion
Plugs airways
Prone to infection
Further inflammation

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What is the result of chronic bronchitis?

 Airway obstruction
 Shortness of breath/ wheezing
 Chest pain, chronic (productive – sputum) cough

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What is the treatment for chronic bronchitis?

 Stop smoking
 Bronchodilators
 Antibiotics

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What is Acute bronchitis?

Due to bacteria/ virus

- Lasts days/ weeks

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What happens in Emphysema?

Smoking -> neutrophils and macrophages release elastase -> elastase destroys alveolar walls -> emphysema
In healthy tissues we have anti-proteases that neutralise elastase (alpha1 antitrypsin) but not in emphysema
Genetic alpha 1 antitrypsin deficiency also leads to emphysema (2% COPD patients)
See increased compliance significantly ABOVE normal
Increased RV (residual volume) -> increased FRC (functional residual capacity): chronically over-inflated lung
Air gets trapped in lungs

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What are the symptoms of emphysema?

 Shortness of breath on exertion
 Hyperventilation
 Expanded chest

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What is used to treat emphysema?

Enzyme supplements in alpha 1 antitrypsin deficiency
Supplemental O2 can be given
Lung transplant the best method of treatment
but loss of alveoli is permanent and irreversible

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What are the symptoms of asthma?

 Increased airway resistance:
 Bronchoconstriction
 Oedema of airway mucosa
 Mucus-secretion

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What are the causes/ precipitating factors of asthma?

 Hypersensitivity reaction to allergens 
 Air pollution 
 Exercise and cold air 
 Emotional stress 
 Genetics?
 Conflicting evidence with causes

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What is the mechanism of asthma?

Mast cell activation -> histamine and cytokine release -> oedema, mucus, smooth muscle contraction - bronchoconstriction

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What is the treatment for asthma?

 Bronchodilators e.g. salbutamol (beta 2 adrenoceptor agonist)
 Anti-inflammatories

What are the main restrictive lung disease disorders?

Fibrosis – development of excessive connective tissue

- Respiratory distress syndrome (IRDS, ARDS, SARS)

What happens in restrictive lung disease?

Alveolar walls become rigid (lungs become rigid)

What happens in acute restrictive lung disease?

Sepsis of severe trauma -> protein exudation -> oedema (thickening of walls)

What happens in chronic restrictive lung disease

Industrial dust, drugs, rheumatism -> inflammation -> fibrosis (alveolar walls replaced by fibrotic tissue)

What happens in fibrosis?

(development of excess connective tissue) – lungs stiffer:
- Alveoli replaced by fibrotic tissue -> DECREASED lung compliance
• Leads to ‘honeycomb lung’ where the lung is so stiff no air can be moved in or out

What are the causes of fibrosis?

Inhaled environmental and occupational pollutants
Cigarette smoke
Autoimmune disease

What is the treatment for fibrosis?

There isn’t one

What type of respiratory tract infections can you get and give some examples?

• Upper respiratory tract infections
- Common but minor
- Average adult gets around 2-4 URTI/year
• Lower respiratory tract infections
- Less common but more serious
- E.g. bronchitis, pneumonia, tuberculosis

What is Pneumonia and what is it caused by?

- acute infection of the lung | - Caused by bacteria: Streptococcus pneumoniae, Staphylococcus aureus or Klebsiella pneumonaiae

What happens in pneumonia?

It affects bronchi and alveoli -> inflammatory exudate fills alveoli -> lead to ‘consolidation’ (lung tissue becomes firm and airless)

What is bronchopneumonia?

 Acute inflammation of the bronchi |  Often accompanied by inflammation in nearby lobules of lung

What is lobar pneumonia?

 Intra-alveolar space affected |  Large area of lung affected

What is Tuberculosis caused by?

- Caused by inhalation of mycobacterium tuberculosis |  Highly contagious

What is TB in it's latent phase?

asymptomatic, non-infectious, granuloma in lung tissue

What happens in the active phase of TB?

- spreads to bronchioles and circulation (10% cases)  Infection in alveoli -> replicate in alveolar macrophage (Ghon focus – site of primary infection)  Initial infection – ineffective immune response  Bacteria then move to lymph nodes (secondary inflammation)  Collagen deposited around bacteria which can cause damage to the lymph nodes  Lymph nodes erodes releasing bacteria  Drainage into bronchioles and blood vessels  Destruction of alveoli

What is the treatment for TB?

- Antibiotics | - difficult because of antibiotic resistance

Give features of COVID-19

- Similar to SARS- 1 - Coronaviruses – coronaviridae family in the Nidovirales order - ‘Corona’ = crown-like spikes on the outer surface of the virus - 65-125 nm in diameter - Contain a single-stranded RNA (26 to 32 kilobases (kb) in length - Believed to be of zoonotic origin

How is COVID-19 transmitted and what happens in the body?

 Primarily via direct contact or through droplets spread by coughing or sneezing  Binding of a receptor expressed by host cells is the first step of viral infection and is then followed by fusion with the cell membrane  Lung epithelial cells thought to be primary target  Receptor = angiotensin – converting enzyme 2 (ACE2) receptor – most abundant in type 2 alveolar cells

How many doses of the Pfizer vaccine are required for full immunity to COVID-19?

two doses

In TB where may the bacteria colonize?

the respiratory passageways, the interstitial spaces, the alveoli or a combination of them

What are symptoms of TB?

coughing and chest pain, fever, night sweats, fatigue and weight loss

What happens in cystic fibrosis?

the respiratory mucosa produce dense, viscous mucus that cannot be transported by the respiratory defence system – the muscocilliary escalatory stops working leading to frequent infections. Mucus also blocks the smaller respiratory passageways making breathing difficult