Respiratory Diseases Flashcards
Air exchange in the lungs
• Pulmonary arteries brings venous blood
• Oxygenated blood leaves the pulmonary veins
• Bronchial arteries bring oxygen and nutrients to lungs
• Originate in the thoracic aorta
Pleural membranes
Envelope the lungs
Visceral (inner) and parietal (outer)
Intrapleural space contains pleural fluid: reduced friction when the lungs move upon inhalation and exhalation
Functions of the respiratory system
• Primary function gas exchange
• Larynx produces the voice
• Mucosa protects against infections: Mucosa-associated lymphoid tissue (MALT), Tonsils in nasopharynx and pharynx, Lymphoid follicles in the wall of the bronchi
• Alveolar macrophages – defense system: Expectorated from the lungs, seen in sputum
• Maintains acid-base function
Contributing factors to respiratory pathologies
The respiratory system is:
1. In direct contact with the environment
2. Exposed to allergens inhaled in the air
3. Inhaled air contains pollutants, airborne particles, and gases that may cause disease
4. Inhaled air contained many potential exogenous carcinogens
5. The heart and lungs form a functional unit
Infectious diseases of the respiratory tract
Two groups based on location:
1. The nose and upper respiratory
2. Lower respiratory
Middle respiratory syndrome mostly childhood diseases involving the trachea and bronchi
• Respiratory tract infections = 75% of all infections
• <5% involve the lung
Upper respiratory infections
• Mostly caused by viruses (colds, flu)
• Rhinovirus (spring and fall), influenza (winter), parainfluenza
• Acute inflammation of the nose, paranasal sinuses, throat, or larynx (or all of them)
• Short lived, heal spontaneously, no benefit of antibiotic treatment
• Can extend into trachea and bronchi
• May be complicated by pneumonia
• Most common location of infection
Upper respiratory infection etiology and pathogenesis
• Mucosa of nose, upper respiratory tract are congested, edematous, infiltrated with inflammatory cells
• Viral: lymphocytes, macrophages and plasma cells
• Bacterial: polymorphonuclear neutrophils (PMNs), yellow pus like exudate
May be complicated by a bacterial superinfection
• Spread into adjacent anatomical structures
• Ex. Bacterial sinusiti
Upper respiratory infection clinical features
Classical “flu like” symptoms
• Nasal congestion, inflammation, rhinorrhea
• Throat pain or discomfort
• Hacking cough
• General malaise
• Fever, headaches, muscle pain
Middle respiratory syndromes
• Infection of the larynx, trachea, major extrapulmonary
bronchi
• Prevalent in children
1. Croup (laryngitis)
2. Acute epiglottitis
3. Viral tracheobronchitis
Croup (an acutely infection of the larynx)
• Children <3 years
• Typically caused by parainfluenza virus
• Acute, potentially life-threatening
• Inflammation of the entire larynx
• Laryngeal swelling and laryngospasm
• Inspiratory stridor (barking or brass cough)
• No specific treatmen
Acute epiglottitis
• School aged children and adolescents
• Inflammation, edema to the epiglottis
• Narrowing of the air passage
• Sudden loss of voice, hoarseness, pain
• Haemophilus influenza
• Prevented with immunization
Bronchiolitis
• Viral infection
• >80% due to respiratory syncytial virus
• Invades epithelial cells of bronchi and bronchioles
• Death and desquamation of cells
• Inflammatory infiltrate (lymphocytes, plasma cells, macrophages)
• Edema of small airways = obstruction of bronchi and bronchioles
Types of Pneumonia (a lower respiratory syndrome)
- Alveolar pneumonia
• Intra-alveolar inflammation
• Etiology = bacterial infection
• Bronchopneumonia (focal)
• Lobar pneumonia (diffuse) - Interstitial pneumonia
• Involves alveolar septa
• Etiology = viral infections
• Diffuse and bilatera
Pathogenesis of pneumonia
Pathogens reach the lungs by:
1. Inhaled air droplets
2. Aspiration of infected secretions upper respiratory tract
3. Aspiration of regurgitated gastric contents
4. Hematogenous spread
Complications of pneumonia
- Pleuritis
• Extension of inflammation to pleural surface → pleural
effusion
• Pyrothorax (pus filled pleural cavity)
• Empyema (fibrotic encasement of pus)
• Slow to heal
• Results in pleural fibrosis
• Restrictive lung disease - Abscess:
• Associated with virulent bacteria
• Destruction of lung parenchyma
• Suppuration (pus forming) - Chronic lung disease
• Unresponsive to treatment
• Bronchiectasis: bronchial wall loss
• Destruction of lung parenchyma & fibrosis results in “honey comb lun
Clinical features of pneumonia
• Systemic signs of infection: fever, chills, prostration
• Local signs of irritation: cough
• Airway obstruction: shortness of breath (dyspnea), rapid
breathing (tachypnea)
• Inflammation and tissue destruction: expectoration of rusty
sputum, hemoptysis (discharge/coughing of blood
Pulmonary tuberculosis
• Chronic bacterial infectious disease
• Bacteria lack attraction of PMN and therefore no purulent
inflammation
• Bacteria elicit formation of granulomas
• Granulomas composed of lymphocytes and macrophages,
multinucleated giant cells
• Central core = necrosis → caseous necrosis
Primary infection (1st exposure):
• Localized inflammation = Ghon’s complex
• Enlarged lymph nodes
• Heals spontaneously
• Calcification
• Can be reactivated
• Secondary Tuberculosis
Dissemination of tuberculosis
Spread through airways, the lymphatic system, or blood (hematogenous)
Complications:
Miliary Tuberculosis
• Widespread seeding of bacteria in lungs and other organs
• Formation of granulomas that resemble millet seeds
Tuberculosis pneumonia
• Spread through air spaces
• Massive lobular or lobar pneumonia
• Same lung of contralateral lung
Pleuritis
• Formation of granulomas on visceral and parietal pleur
Chronic bronchitis (COPD)
• 90% of cases due to smoking
• Air pollution, toxic fumes, respiratory infections
• Thick bronchi and bronchiole walls
• Mucosa infiltrated with lymphocytes, macrophages and plasma cells
• Submucosa shows mucous gland hyperplasia, chronic inflammation
and fibrosis
• Excess production of tracheobronchial mucus
• Cough and expectoration for at least 3 months during 2 consecutive years
Bronchiectasis (COPD)
• Permanent dilation of bronchi
• Persistent inflammation in airways
• Filled with mucopurulent material which stagnates and cannot be cleared with coughing
• Spreads: intraparenchymal, hematogenous
• Fever, malaise, fatigue
Emphysema (COPD)
• Enlargement of air spaces in bronchioles
• Destruction of alveolar walls
1. Centrilobular
• Air space in center of lobule/bronchiole
• Smokers
• Leukocytes, proteolytic enzymes, elastic fibers
2. Panacinar
• Air space distal to terminal bronchioles
• Loss of elastic fibers in alveolar walls
• anti-trypsin deficiency ( 1-AT)
Bronchitis vs emphysema
Bronchitis “Blue Bloaters”
• Prolonged coughing, expectorate, dyspnea, hypoxia → cyanosis
• Bronchial fibrosis → pulmonary hypertension
• Right heart failure → peripheral venous stagnation → cyanosis
• Enlarged heart
Emphysema “Pink Puffers”
• Reduced respiratory surface → compensatory tachypnea
• Hyperventilate to oxygenate blood
• Chest overexpanded (“barrel-
chest”)
• Small heart
Asthma
• Increased responsiveness of bronchial tree to a variety of stimuli
• Acute to chronic inflammatory response
• Reversible airway obstruction
• Marked by wheezing, coughing, dyspnea
• ~10% children, 5% adults
• 50% of cases begin in childhood
• 2:1 male to female ratio
Two types of asthma
- Atopic: extrinsic allergen
• Type I hypersensitivity reaction, IgE - Nonatopic: intrinsic – attacks
• Physical factors (heat or cold)
• Exercise
• Psychological stress
• Chemical irritants, air pollution
• Bronchial infection
