Respiratory Flashcards
Function of the lungs
oxygenation of blood and removal of waste products (CO2)
Respiration requires 2 main functions
ventilation (movement of air) and perfusion (movement of blood)
Structure of the resp system
Airways, acini and secondary lobules, vasculature, lymphatics and pleura
What do your airways include
Trachea, bronchi and bronchioles which include the terminal bronchioles and respiratory bronchioles
What are the basic units of gas exchange
Acini
What are acini
Units supplied by a single terminal bronchiole, includes resp bronchioles, distant alveolar ducts and alveolar sacs
What cells are alveolar sacs lined with
Type 1 and Type 2 Pneumocytes
Type 2 Pneumocyte cells are the ________ cellsfor type 1 cells and produce _________
progenitor, surfactant
Where does gas transfer take place in the lungs
alveolar-capillary membrane
What does the alveolar capillary membrane consist of
capillary endothelium, basement membrane and surrounding interstitial tissue, Alveolar epithelium (type 1 and 2 pneumocytes)
Which side of the lung does deoxygenated blood come from
right
Two types of perfusion in resp
Bronchial - oxygenated blood from descending aorta and intercostal arteries supplies lung
parenchyma
Pulmonary - - pulmonary artery carries deoxygenated blood from right side of the heart to the lungs.
Intimate contact between air in alveoli and blood in pulmonary capillaries allows gaseous exchange to
take place. Oxygenated blood returns via pulmonary vein to left atrium
What is resp failure
Inability to maintain normal oxygen saturation of blood and to remove CO2 from blood entering the lungs
What can resp failure be due to
decreased ventilation
decreased perfusion
ventilation/perfusion imbalance
What is the pleura
the membrane that covers the lungs and lines the walls of the pleural cavity; visceral and parietal
What is it called between the visceral and parietal pleura of the lungs
pleaural cavity
Which pleura is on the outside vs the inside
Outside - Parietal
Inside - Visceral
Which 2 systems can injury to the lung be mediated through
Airways or blood vessel systems
What are most injuries to the lungs a result of?
Inhaling something
Inhaled injurious objects can be … (2)
- infectious (virus, bacteria, fungi, etc.)
2. non-infectious (toxic gases, cigarette smoke/particles).
Mechanisms of defense to inhaled objects
- Nasal clearance
- Tracheobronchial clearance by muco-ciliary “blanket” - clears smaller particles to be coughed up
- Alveolar clearance by macrophage system/immune system
Explain the 3 systems of defense to inhaled objects working together to eliminate the problem
Large particles (>5 µ) are trapped in the nose; the mucociliary blanket of the airway epithelium disposes of intermediate sized particles 3 to 5 µ; smaller particles (<2 µ) are trapped in the air spaces and are removed by alveolar macrophages. Very small particles are breathed out
Are pulmonary infections more or less frequent than other organs
More
Which area of the lungs do most infections fester and what are they caused by
Upper respiratory tract infections caused by viruses
What is the basic description of pneumonia
Inflammation of the lung secondary to infection
What organisms are involved in pneumonia
bacteria
viruses
fungi
protozoa (unicellular eukaryotic organisms)
rickettsia (a diverse collection of obligately intracellular Gram-negative bacteria found in ticks, lice, fleas, mites, chiggers, and mammals. They include the genera Rickettsiae, Ehrlichia, Orientia, and Coxiella. These zoonotic pathogens cause infections that disseminate in the blood to many organs)
others
Organisms enter the lung most commonly as aspiration of what? Less commonly?
- aspiration of organisms that colonize the oropharynx
- less commonly by inhalation of infected aerosols, hematogenous dissemination (spread by blood stream) and direct inoculation
Whenever the defense mechanisms are impaired
or whenever the resistance of the host is impaired, what can result? These factors include…
Pneumonia
-cigarette smoking, chronic bronchitis, alcoholism, severe malnutrition, wasting diseases, and poorly controlled diabetes
What 2 ways can pneumonia be classified?
morphologically (histologic and morphologic appearance) or clinically (how and where acquired)
Factors which determine whether infection will occur depend on which 2 things?
- Dose and virulence of the organisms
- Host susceptibility - pneumonia will occur if:
i) defense mechanisms are impaired
ii) impaired resistance (immunocompromised)
4 examples of impaired host defense
1) Loss or suppression of the cough reflex (e.g., coma, anaesthetic)
2) Injury to the mucociliary apparatus
(e. g., cigarette smoking, inhalation of corrosive gases)
3) Interference with alveolar macrophages
(e. g., alcoholism, malnutrition)
4) Accumulation of fluid or secretions in alveoli
(e. g., pulmonary edema, cystic fibrosis
2 Types of morphologic Pneumonia
i) Lobar pneumonia - the entire lung or lobe is involved due to organisms which can spread very rapidly
ii) Bronchopneumonia - infection is spread by the airways, therefore, this type tends to be patchy
In what types of people are lobar pneumonia seen? What about Bronchopneumonia?
- Debilitated people
2. In extremes in life and as complications of Viral infections
Of the 2 types of pneumonias, most bacterial pneumonias are more likely to show which pattern?
Broncho
3 clinical classifications of pneumonia
- Community acquired - organisms involved include Streptococcus pneumoniae, Hemophilus
influenzae, and Mycoplasma pneumoniae - Nosocomial (hospital or nursing home acquired) - organisms involved include enteric gram ne.g.,ative
bacilli, Pseudomonas aeruginosa, Staphylococcus aureus and oral anaerobes. - Pneumonia in immunocompromised patients - organisms involved include CMV, fungal organisms,
tuberculosis, pneumocystis. Immunocompromised patients are more susceptible to infection than
healthy patients. Virulent organisms will cause more severe infections than in healthy individuals.
Organisms which would be unusual in healthy individuals may also cause significant infections in the
immunocompromised host
What does nosocomial pneumonia mean
Hospital or nursing home acquired
Clinical presentation of pneumonia
Pneumonia presents with a sudden onset of fever and chills, malaise, and pain on
inspiration (from pleuritis). Cold sores on the lips may flare up
How to diagnose pneumonia
Based on the clinical presentation, typical x-ray appearance, the finding of neutrophils in the
sputum and identifying the organisms
Neutrophils in the sputum could mean what?
Pneumonia
3 complications of pneumonia
-Lung abscess formation: defined as a localized collection of pus, may be a complication of bacterial
pneumonia
-Empyema: The infection spreads to the chest cavity
-Septicemia: The organisms spread beyond the lung via the blood stream
What is a lung abscess formation commonly associated with?
depressed cough reflex (alcohol)
Why is a lung abscess more commonly found in the right lobe?
the left main stem bronchus comes off the trachea
at a greater angle than the right main bronchus, and is therefore relatively protected from aspiration
Issues associated with TB
a) A major cause of morbidity and mortality in the world
b) Increased incidence in North America
c) Increased incidence of multi-drug resistant strains
2 categories of non-infectious diseases of the lungs
non-neoplastic (obstructive and restrictive) and neoplastic
Explain obstructive lung diseases
-involve the airway and are characterized by increased resistance to airflow due to
partial or complete obstruction of the airway from the trachea to the bronchioles
-This condition may be acute
(e.g. Aspiration of a foreign object) or chronic
Explain restrictive lung disease
-reduced expansion of the lung = decrease in
the total lung capacity
-may be due to an abnormality of the chest wall or the lung
Common features of Chronic Obstructive lung diseases
- patient presents with shortness of breath
- recurrent airflow obstruction
3 common Chronic Obstructive lung diseases
Bronchial asthma
Bronchitis
Emphysema
Bronchial Asthma is a _______ disorder characterized by…
INFLAMMATORY
i) hyper-reactive airways - secondary to increased responsiveness of the airways to various stimuli
ii) Episodic and reversible bronchoconstriction
The various stimuli involved in Bronchial Asthma include…
exposure to an allergen, temperature (cold or heat), infectious agent, exercise, or emotional stress
In Bronchial asthma, the patient may be ______ between attacks. However, the attacks can be fatal due to what?
Asymptomatic unremitting attacks (status asthmaticus)
Define chronic bronchitis
A patient with a persistent cough with sputum production for a least three months of the year, in at least two consecutive years
Explain how cigarette smoke leads to chronic bronchitis
The cigarette smoke will impair ciliary action and cause hypersecretion of mucus. This will lead to airway obstruction and impairment of gas exchange
Patients with chronic bronchitis are at risk for what?
increased risk of pulmonary infections and the development of pulmonary hypertension
Emphysema effects ___% of the population >50 y.o
50%
Emphysema is characterized by …
damage to the distal part of the lung (acinus) leading to abnormal and permanent enlargement of the airspaces
What is emphysema significantly associated with? Why?
Cigarette smoke
-smokers exhibit more lung destruction than non-smokers
What are restrictive lung diseases also known as?
Interstitial lung disease
Restrictive lung disease account for ___% of all non-infectious lung diseases
15%
Common features of restrictive lung diseases
i) Patients present with cyanosis, dyspnea, tachypnea and no evidence of airway obstruction
ii) Reduced lung volume
iii) Reduce lung compliance
iv) Reduced oxygen diffusion capacity
v) Involvement of the alveolar wall
Some lung diseases of unknown etiology
sarcoidosis and idiopathic pulmonary fibrosis
Lung cancer accounts for ___% of all new cancer cases in humans and ___% of all cancer deaths
14%
26%
What is the #1 etiology of lung cancer
Cigarette smoking
What % of lung cancer occurs in smokers?
80%
What are other etiological agents of lung cancer?
uranium, radiation and asbestos
4 types of lung carcinoma
- squamous cell carcinoma
- adenocarcinoma
- small cell carcinoma
- large cell undifferentiated carcinoma
Prognosis of lung cancer is dependent on
- The tumour type - small cell carcinoma has the worse prognosis
- Stage at presentation - the stage is the extent of the tumour at the time of diagnosis
4 stages of lung cancer
Stage 1: tumour is confined to the lung (no metastasis)
Stage 2: tumour is in the lung and spread to parenchymal lymph nodes
Stage 3: tumour in the lung and spread to mediastinal lymph nodes
Stage 4: the tumour has spread to distant sites
Effects of pulmonary neoplasm depends on ______ and can be either ____ or ____.
- location
- local
- distant
Which lung tumors may present earlier and why?
Tumors which take their origin close to the hilum (e.g. squamous cell carcinoma and small cell carcinoma) are
more likely to produce local effects and as a result may present earlier than tumors which grow at the
periphery of the lung (i.e. in a silent area, e.g. adenocarcinoma)
Local effects of pulmonary carcinoma
i) obstruction of an airway
ii) direct invasion of adjacent structures (chest or mediastinum)
Distant effects of pulmonary carcinoma
i) metastatic spread via lymphatics or blood
ii) paraneoplastic effects; symptoms in patients which cannot be explained by local or distant spread of
the tumor
Diagnosis of lung carcinoma is based on
- History and physical examination (Patients may present with cough, weight loss, chest pain, or dyspnea)
- Radiologic examination - chest x-ray or CT scan
- Tissue diagnosis - biopsy of the tumour to identify malignant cells. Occur via:
i) Examination of the sputum
ii) Bronchoscopic biopsy
iii) Fine needle aspiration biopsy
Treatment of lung carcinoma
-If the patient is operable (i.e. stage 1 or 2) then formal resection either of a lobe or of a lung is undertaken.
-Inoperable tumours are treated with either radiation or chemotherapy or a combination of the two. Since small
cell carcinoma have a very bad prognosis these patients are not subjected to operation, but are treated with chemotherapy
Why is the lung a common site for metastasis from other sites
Due to its rich blood supply
