Respiratory system and diseases I and II Flashcards
what are the most frequent/common diseases in the respiratory tract
The most frequent diseases in respiratory tract are upper respiratory tract infections(bacterial, viral)
other than upper respiratory tract infections which othe rinfections are important
lobar pneumonia, tuberculosis & opportunistic infections
what are the common chronic lung diseases
asthma, chronic bronchitis, emphysema & pulmonary fibrosis
where in the resp system can Clinically important tumours form
from bronchial tree and lung are common; almost all malignant
in the resp system give an example of dysfunction secondary to diseases from other systems
pulmonary oedema due to heart failure
what does the trachea consist of
- Cartilage plates & smooth muscle
- Respiratory epithelium
- Submucosal glands
what is the structure of the bronchi
- Cartilage foci & smooth muscle
- Respiratory epithelium
- Submucosal glands
what is the structure of the bronchioles
- No cartilage, thinner muscular layer
- Simple ciliated epithelium
- Clara cells
what do alveoli consist of
type I and type II pneumocytes
describe the structure of respiratory mucosa cells
- pseudostratified, columnar, ciliated epithelium with mucus-secreting goblet cells
what is the main defence mechanism of the resp system
ciliated epithelium
where does the common cold infect
upper respiratory tract
describe the common cold
- A catarrhal disorder of upper respiratory tract, very common
- Mainly by rhinoviruses (picornavirus group, over 100 strains - vaccination impracticable)
- Spread by close personal contact, droplets
- Pathology: inflamed mucosal membrane of the nose
where does influenza infect
upper respiratory tract
describe influenza
- Influenza virus (orthomyxovirus), main forms A, B
- type A: cause for pandemics
- ~10,000 deaths per year in UK
- Haemagglutinin (H) – cell attachment
- Neuraminidase (N) – cell penetration
- H1-H3 and N1&N2 subtypes have established stable lineage in human population
describe genetic variations of influenza spread incubation symptoms prophylaxis
- Genetic variations of the virus:
- Major antigenic shift can caus pandemics
- Minor antigenic drift can cause less severe epidemics
- Spread: By droplets and fomites
- Incubation:−1-3 days
- Symptoms:−Fever, shivering, generalised aching (limbs)−Severe headache, sore throat, persistent dry cough
- Prophylaxis:
- Influenza vaccines; recent advance: M2-protein based multi-strain vaccine; universal vaccine targeting core proteins on trial
what is pneuomonia
how is it classified
Inflammation of alveoli, usually caused by bacteria
Classifications:
- Anatomical:Lobar pneumonia (whole of one lobe)
- Bronchopneumonia (lobules and bronchi)
Aetiological:Bacterial, Viral, Other
what is a common cause of pneumonia
STREPTOCOCCUS PNEUMONIA
- causes acquired acute pneumonia
who does bronchopneumonia affect
Most commonly in old age, infancy andpatients with debilitating diseases
who does lobar pneumonia
Typically affects healthy adults between 20-50 yrs
what is the pathology of pneumonia
- alveolar inflammtion
- alveoli become filled with protein rich exudate
- Bronchopneumonia:
- Focal inflammation along the airways (patchy consolidation), often bilateral of the lung
- Lobar pneumonia:
- Diffuse inflammation affecting the entire lobe; pleural exudate common
what are the clinical features, symptoms and signs of pneumonia
SYMPTOMS:
respiratory symptoms: cough, purulent or rusty sputum, dyspnoea (difficulty breathing)
systemic symptoms:
pyrexia (fever)
SIGNS:
- consolidation (THE LUNG is normally full of air but in pneumonia the lungs are filled with fluid)
- pleural rub (pleural cavity should be empty but in pneumonia it is filled with protein exudate)
but elderly patients often have fewer symptoms
what investigations can we do for pneumonia
- Chest X-ray (cheap, specific)
- Blood cell count:
- WBC count >15x10^9/L suggests bacterial infection
Sputum:
- Gram stain, culture & sensitivity tests
Other specific tests:
- Myoplasma, legionella (these are gram negative bacilli)
how can we manage pneumonia
if COMMUNITY ACQUIRED:
- antibiotics immediately without waiting for microbial results
if HOSPITAL ACQUIRED:
- Often Gram-negative organisms; different antibiotics
- treatment should be modified for depending on the bacterial culture and sensitivity results
Specific measures:
- Analgesia (pleuritic pain)−O2 therapy (hypoxaemia)−Intensive care (severe pneumonia)
what complications of pneumonia can arise
- lung abscess (liquefactive necrosis of the lung tissue and formation of cavities containing necrotic debris or fluid caused by microbial infection)
- empyma (collection of pus in the pleural cavity)
what is tuberculosis (TB)
- The world’s leading cause of death from a single infectious disease
- Major cause of death/morbidity in developing countries
- Prevalence on the increase in developed countries
- Lung – the commonest site
what is the cause, transmission and predisposing factors of TB
Caused mainly by:−Mycobacterium tuberculosis
Transmission:
- Through the air, or from direct contact
Predisposing factors: −Alcohol, diabetes, immunosuppression
what is the pathogenesis of TB
1) First infection with mycobacteria (primary tuberculosis)
2) Initial reaction & macrophage ingestion
3) Interacting with T-cells & development of cellular immunity
4) DELAYED HYPERSENSITIVITY REACTION ADN TISSUE NECROSIS
5) Healing & calcification
6) REACTIVATION: (diabetes, malnutrition, immunosuppression)
7) Adult post-primary pulmonary tuberculosis
what is the pathology of TB
Primary TB: small GRANULOMAS in lobes (Ghon complex) often resolves
Secondary TB: Reactivation; lesions in apices: caseous necrosis in granulomas, convert to fibrocalcific scars
Miliary tuberculosis:
disseminated GRANULOMAS in many
what are the clinical features of TB
primary TB: usually asymptomatic
but if symptoms are experienced@ cough, chest pain, and fever
purulent sputum
Diagnosis:
- chest x- ray (upper zone shadows, fibrosis)
- sputum samples (stain and culture)
how can TB be prevented and treated
Prevention: BCG (bacille Calmette-Guerin)vaccination
Treatment: 3 or 4 different antibiotics in combination over 6 to 9 months
what is COPD Chronic obstructive pulmonary disease
- Characterised by poorly reversible airflow limitation, usually progressive
- Associated with a persistent inflammatory response of the lung
- Predominantly caused by smoking in developed countries
- A term for patients with airflow obstruction, including chronic bronchitis or emphysema
EPIDEMIOLOGY:
- Develops over many years; rarely symptomatic before middle age
- Common in UK, 18% of male smokers, 14% of female smokers; one of leading causes of lost working days
what is the aetiology of COPD
- SMOKING is the dominant causal agent
1) smoking activates macrophages in the epithelial cell region
2) causes release of CHEMOTACTIC factors
3) this activates GRANULOCYTES
4) causing the release of PROTEASES
5) this damages cells - there is an imbalance of proteases/protease inhibitors in COPD
- also ATMOSPHERIC POLLUTION: has a minor role in comparison with smoking
- also alpha1- antitrypsin: a rare cause of early onset emphysema
what is the pathology of COPD
CHRONIC BRONCHITIS:
- chronic inflammation of airways (caused by predominantly lymphocytes)
- enlargement of mucus secreting glands of trachea and bronchi
- airway narrowing and O AIRFLOW LIMITATION
EMPHYSEMA:
- dilation and destruction of the lung tissue distal to terminal bronchioles
- loss of elastic recoil, expiratory airlow limitation and air trapping
what are the characteristic symptoms and signs of COPD
SYMPTOMS: - cough - sputum - breathlessness - wheeze SIGNS: - tachypnoea (abnormally rapid breathing) - use of accessory muscles in breathing - hyperinflation - poor expansion - others: cyanosis (blueish tinge to skin), cor pulmonale (enlargement of the right side of the heart)
what are the investigations for COPD
LUNG FUNCTION TESTS: - DECREASED FEV and DECREASED FEV1/FVC CHEST X RAY: - lungs hyperinflated ARTERIAL BLOOD GASES: - normal or hypoxia and hypercapnia ( elevated carbon dioxide levels in the blood) HAEMOGLOBIN and PCV may be high ECG and echocardiography : - assess cardiac status if clincal features of cor pulmonale
what is cor pulmonale
abnormal enlargement of the right side of the heart as a result of disease of the lungs or the pulmonary blood vessels
how is COPD treated
complications
prognosis
TREATMENT:
- smoking cessation
- drug therapy (bronchodilators, corticosteroids, antibiotics)
- treatment of respiratory failure
- other measures - heart failure, secondary polycythaemia
COMPLICATIONS:
- respiratory failure
- Cor pulmonale (right heart failure secondary to lung disease)
PROGNOSIS:
- 50% of patients with severe breathlessness die within 5 years
what is asthma
- chronic inflammatory condition of the lungs
- Hyper-reactivity of the bronchial tree with paroxysmal narrowing of the airways
- 3 main characteristics: airflow limitation, airway hyperesponsiveness and inflammation of the bronchi
- airflow limitation is often REVERSIBLE
epidemiology:
The prevalence is increasing; geographical variation: more common in developed countries; much rarer in Far Eastern countries
what is the aetiolgy of asthma
2 major factors:
1) Atopy and allergy: Readily develop IgE against common environmental antigens; genetic and environmental factors affect IgE levels
2) Increased responsiveness of the airways ofthe lung (a fall in FEV1) to stimuli
what is the pathogenesis of asthma
Primary abnormality:
- Narrowing of the airway
−Thickening of the airway wall
−Secretions within the airway lumen
Inflammation:
Cellular components: eosinophils, T lymphocytes, macrophages and mast cells which release inflammatory mediators
Remodelling:
structural changes in the airway
what are precipitating factors in asthma
Occupational sensitizers:
- Over 200 materials encountered at workplace may giverise to wheezing, which typically improves on days off- (occupational asthma)
Non-specific factors that cause wheezing:
- viral infections, cold air, exercise, irritant dusts,vapours and fumes, emotion and drugs
Rare cause of asthma:
- airborne spores of Aspergillus fumagatus (soil mould)
what are the clinical features of asthma
- Wheezing attacks
- Episodic shortness of breath
- Some have one or two attacks a year;others have chronic symptoms
- On examination, during attack:−reduced chest expansion, prolonged expiratory time and bilateral expiratory polyphonic wheezes
what investigations can be done on asthmatic patients
- Diagnosis often made on the history and response to bronchodilators. No single satisfactory diagnostic test for all
LUNG FUNCTION TESTS:
- Demonstration of variable airflow limitation ( PEFR or FEV1)
TESTS FOR ALLERGY/HYPERSENSITIVITY:
- Airway responsiveness (histamine or methacholine)−Test of allergy (skin-prick tests)−Blood and sputum for eosinophils & Aspergillus antibody
CHEST X RAY (at diagnosis and only repeated in the case of an acute severe attack)
TRIAL OF STEROIDS REVERSIBLY:
- to those with severe airflow limitation - reversibility (↑FEV1 > 15%)
EXERCISE TESTS (in children)
how can asthma be treated
- control extrinsic factors
- drug treatment:
Bronchodilators:
ß2-adrenergic agonists
Antimuscarinic bronchodilators
Theophyllines
Anti-inflammatory agents:
steroids
Chromones
Leukotriene receptor antagonists
Immunosuppressive agents
what are the 2 types of lung tumour
- primary
- secondary
describe primary carcinoma of the lung (bronchial carcinoma)
- Accounts for 95% of all primary tumours of the lung
- Most common malignant tumour in the world
- poor prognosis:
- 5 year survival rate <10%
what are the major risk factors/ aetiology in primary carcinoma of the lung
- Directly related to smoking
- Associated with occupational exposure to carcinogens
- Pulmonary fibrosis
what is the pathology of primary carcinoma of the lung
- most arising form bronchi (hilum)
- main histological types:
- Squamous cell carcinoma
- Small cell lung carcinoma
- Adenocarcinoma
- Large cell undifferentiated carcinoma
what are the clinical features of primary carcinoma pf the lung
- Cough
- Chest pain
- Haemoptysis
- Weight loss
how is primary carcinoma diagnosed
- Chest X-ray
- CT
- Biopsy & cytology
how is primary carcinoma treated
- Surgical resection
- Non small cell lung cancer
- Chemotherapy
- Small cell lung cancer
- Radiotherapy
- Localised tumours
overall poor prognosis
Recent advances:
specific targeted therapies: EGFR mutation –EGFR tyrosine kinase inhibitorALK fusion oncogene –ALK inhibitor
