W8: Pulmonary Flashcards
How many lobes to the left and right lung have?
Right lung: 3 lobes
Left lung: 2 lobes
Dsecribe the pleural surface of the lungs
- the surface of the lungs are covered by a lining called pleura
- the pleura covering the outer surface of the lungs: visceral pleura is continuous with the parietal pleura that covers inside the thoracic cage
- pleural surfaces are moist to allow surfaces to slide over each other
Epithelia of the nasal cavity and paranasal sinuses
- cuboid epithelium- composed of ciliated and mucus producing cells
- function to keep nasal pasages moist and to filter air
- mucus contains bacteriacidal substances
- cilia helps remove muscu from nasal passages
Epithelium of pharynx and larynx
- squamous epithelium (identical to mouth)
- sturdy- provides protection to injury
- mucosa of the pharynx is rich in lymphoid tissue. This is a source for antibodies, but also goes through hyperplasia during infection
Epithelium of the trachea
-trachea and bronchi are lined with cuboidal epithelium
contains 4 cell typies: ciliated, mucus producing, neuroendocine, and basal cells
-under pathologic conditions, basal cells proliferate, and become squamous. Most lung cancers originate from bronchial epithelium. 4 cell types, this is why there are several histolic types of lung cancer.
The alveoli are lined with
- pneumocytes
- type1: 90% of alveolar surface - very thin cells designed to allow passaege of air to the blood
- type 2: cuboidal cells, specialize in the production of pulmonary surfactant (mix of lipids, protein, carbohydrates), which keeps the alveoli open and prevents them from collapsing
Histology of Bronchi and Alveoli: image
External surface of the lung is covered with
- mesothelium and underlying connective tissue
- mesothelium is an epithlial layer that lines both the visceral and parietal pleura
Pulmonary Circulation image
Describe Pulmonary Blood Supply
- the lungs have dual blood supply
- the pulmonary artery brings venous blood supply from right ventricle into the lungs to be oxygenated in the alveolar speta
- the oxygenated blood leaves the lungs through the pulmonary veins which drain into the left atrium
how are nutrients brought to the lungs?
through bronchial arteries, which originate in the thoracic aorta
Preconditions for normal respiration
- airways must be patent
- lungs must be able to expand rhythmically during each respiratory movement
- alveolar respiratory membrane must be in tact
- action of control centers in CNS, thoracic muscles and diaphragm must be properly coordinated
Metabolic function of the lungs
-maintain acid/base balance
Facts to know about the respiratory system
- ) is an open-ended system with direct contact with the environment (risk for URI, bronchitis, pneumonia)
- ) exposed to many allergens in air (immunologic diseases)
- )Inhaled air contains pollutants, airborne particles, and gases which may cause disease
- ) Heart and lungs form a functional unit
- ) Inhaled air contains many potential carcinogens
Most common cause of death in the elderly, and people with cancer, and immune diseases
Upper Respiratory Infections
most recognised as, characterized by, tendency to
- most often recognised as the common cold
- characterized by acute inflamation of the nose, sinus, throat, larynx
- tendency to extend to trachea and bronchi
Etiology of URI
- most often caused by viruses, though impractical to isolate the virus in every case
- short lived, heal spontaneously, are not helped by abx
- common cold is most often caused by rhinovirus, up to 50%, common in spring or fall
- influenza and parainfluenza can also cause colds in the winter
Pathology of URI
- largely non-specific
- mucosa of nose and upper resp. tract is congested, edematous, infiltrated with inflammatory cells
- cells infiltrates lynphocytes, macrophages, and plasma cells
- severe infections may cause ulceration of mucosal lining, causeing infection.
- Bacterial infections elicit PMN’s which cause mucopurlent exudate
Clinical Features of URI
- nasal congestion, inflammation and rhinorhea
- throat pain, sneezing, cough
systemic: malaise, fever, headache - last 2-3 days, even though fever may persist for a day or 2 longer
- purulent nasal discharge, ear pain, deep throat expecteration are signs of bacterial superinfection
What are middle respiratory infections?
- Infections of the larynx, trachea, and extrapulmonary bronchi
- most common in children, and include isolated laryngitis presenting as croup, acute epiglotitis, and viral tracheobronchitis
- can be an extention of URI, and are commonly associated with pneumonia
What is croup?
most common in, patho, caused by, mild or severe?
Infection of larynx and adjacent structures
- most common in children under 3
- spasm of the vocal chords, which causes inspiratory stridor= barking or brass cough
- typically caused by parainfluenza virus
- 80% mild form of disease
Epiglotitis
- previously common, caused by haemophilis influenzae
- school aged children and adolescents. Vaccine reduced
- Sudden loss of voice and hoarseness, throat pain on swallowing
- narrowing of air passage due to edema of epiglotis and inflammation of pharangeal mucosa
- abx. and supportive therapy with humidified 02
- severe cases tracheal intubation
Bronchiolitis
- acute childhood disease involving bronchi and bronchioles but not alveolar spaces of the lungs
- Viral infection, 80% RSV
- virus invades epithelial cells of bronchi and bronchioles, causing cell death and desquamation
- also incites inflammatory response with macrophages, plasma cells, lymphocytes
- Desquamation and inflammatory infiltrate, dead cells, edema, cause obstruction of bronchi and bronchioli
- occurs in epidemics from fall to spring, 1% of infants
- wheezing respiration, low grade fever, SOB
- unless bacterial infection, recovery in 7-10 days
Pneumonia: 2 major forms
- inflammation of the lung
- Alveolar pneumonia: caused by bacteria, focal or diffuse,. May be limited to the alveoli, or involve the bronchi.
- Bronchopneumonia: limited to segmental bronchi and lung parenchyma
- lobular pneumonia: widespread alveolar pneumonia
-Interstitial pneumonia: Diffuse, bilateral, caused by infections with viruses. Mycoplasma pneumonia.
Chronic Pneumonia is typical of…
TB
Fungal infections
Bacteria accounts for what percentage of pneumonias
-75%
Pneumonias can be classified etiologically by which causes
Upper respiratory flora: is a mixture of bacteria. When entered into the lower respiratory systems, will cause pneumonia. Most common -Streptococcus pneumoniae, Haemophilus influenzae, and Staphylococcus aureus.”
Enteric Saprophytes: Anaerobic bacteris such as e.coli or pseudomonas are part of normal enteric flora. Will cause bacteria if entered into resp.
Extraneous Pathogens: Bacteria such as legionella or TB
Routes that bacteria responsible for pneumonia enter the lungs
- inhalation of pathogens in air droplets (virus)
- Apiration of infected secretions from upper resp. tract (strep & staph)
- Apiration of infected gastric contents, foods, drinks (anaerobic bacteria)
- Hematogenous spread: transport to the lungs by blood. Common in bacteremia (sepsis)
-
Pathology of Alveolar Pneumonia
Broncho-pneumonia: typically begins with bacterial invasion of the bronchial or bronchiolar mucosa. Followed by exudation of PMNs into the lumen of the airways. The inflammation spreads from the bronchi into the adjacent alveoli. I
Hypostatic pneumonia: the infection is pre-ceded by pulmonary edema. In either case the inflammation may be limited to a small number of single lobules (lobular pneumonia), or it may be spread through large por-tions of the pulmonary parenchyma (lobar pneumonia).
As the intraalveolar exudate accumulates, it replaces the air, and the lung parenchyma becomes consolidated.
Because consolidated lung parenchyma is denser than normal lung, pneumonia can be recognized on x-ray studies as “infiltrates” or “consolidation of parenchyma.”
With appropriate treatment, the pulmonary infection can be brought under control and the pneumonia cured. The exudate is resorbed or coughed out with complete restitution of the normal alveolar spaces
Pathology of interstitial pneumonia
Interstitial pneumonia: usually diffuse and often bilateral, differ from alveolar pneumonias in that the inflammation primarily affects the alveolar septa and does not result in exudation of PMNs into the alveolar lumen.
In contrast to alveolar pneumonia, which is usually caused by bacteria, interstitial pneumonias are caused by viruses or M. pneumoniae that attach to the surface of respira-tory epithelial cells.
These pathogens cause cell necrosis and induce an infiltrate predominantly restricted to the alveolar septa. This accounts for the so-called reticular pattern, with no major consolidations typically seen on radiographic examination. Fortunately, most interstitial pneumonias cause only minor alveolar damage and resolve without consequence.
Som may result in chronic pneumonia- characterized by interstitial fibrosis and honeycomb appearance of lung
-atypical course- may pass undiagnosed
Most NB complications of bacterial pneumonia
- Pleuritis: Etension of inflammation to the pleural surface leads to pleural effusion. Some-times, especially with purulent bacteria, pus fills the entire pleural cavity (pyothorax); more often pus is encapsulated by fibrous tissue into pockets called empyema. Suppurative pleuritis heals slowly and usually results in pleural fibrosis encasing the entire lung. Pleural fibrosis obliterates the pleural cavity. Because the lungs cannot expand during inspiration, restrictive lung disease results.
- Abscess: highly virulent bacteria (staff), may destory lung parenchyma and suppuration
- Chronic lung disease: Complication whe pneumonia is not responsive to tx. Pus inside bronchi causes destruction of their walls and broncial dilation (bronchiectasis). Honeycomb lung: desruction of parenchyma and fibrosis
Complication of viral pneumonia
Rare b/c most heal spontaneously
some will not resolve and then become chronic pneumonia. Intersitial fibrosis and bacterial superinfection
Pneumonia primarily affects which age groups?
- under 5
- over70
Primary vs. secondary pneumonia
-Primary: Community aquired, healthy people
Secondary: hospital aquired (nosocomal) or in people with pre-existing conditions
Risk factors for pneumonia
-elderly, alcoholism, smoking, immunosupression
Symptoms of pneumonia can be classified as
- systemic signs of infection: high fever, chills, prostration
- local signs of infection: related to bronchial inflammation that promote secretion of mucus. Plugging airways causes irritation, coughing, and expectoration. Pleural inflammation causes cp
- airway obstruction: impaired gas exchange causes dyspnea and tachypnea
- inflammation and tissue destruction: inflammatory exudate causes tissue destruction and bleeding. Mucupulrulent, blood tinged (rusty) sputum
Clinical Findings of Pneumonia
- distress, SOB
- relentless coughing
- auscultation: rales, other symptoms of consolidation
Pneumonia is confirmed by
- CXR
- bacteriologic studies of sputum
- peripheral blood sample:
- bacterial pneumonia accompanied by leukocytosis
- viral: may have elevated lymphocytes
- hypercapnia, hypoxemia, respiratory acidosis (low ph)
Common form of atypical pneumonia
-mycoplasma pneumoniea
More than 50% of bacterial pneumonia is caused by
s. pneumoniae
Pneumonia with multiple abscesses is caused by
staph aureus
most common gram negative hospital aquired pneumonia
pseudamonas pneumoniae
most common cause of lung infection with cystic fibrosis
P.aeruginosa