Pathology and Histology Flashcards
What is pneumonia?
Infection involving the distal aspects of the respiratory tree including localised oedema
What is lobar pneumonia?
Pneumonia involving a complete lung lobe
What are the different types of pneumonia (based on where infection was acquired)?
- Community acquired
- Hospital aquired
- Aspiration
During a classical acute inflammatory response what are the main stages in a pneumonia?
- Exudation - emission of fibrin-rich fluid through pores or wounds
- Infiltration by neutrophils
- Infiltration by macrophages
- Resolution
Why is pneumonia potentially able to cause long term damage?
Organisation of tissues during healing can cause fibrous scarring
Abcesses can form
Bronchiestasis can occur - abnormal dilation of bronchi
Empyema - collection of pus in body cavity most commonly the pleura
What is bronchopneumonia?
This is when infection causing pneumonia starts in the airways and proceeds to infect the alveolar lung
This is common when the patient has pre-existing disease
Which pathogens can cause bronchpneumonia?
Strep. pneumoniae, Haemophilius influenza, S. aureus, anaerobes and coliforms
What is an abscess?
A local collection of pus
Can cause chronic malaise and fever
Caused by aspiration of pathogens
What is bronchiestasis?
Fixed dilatation of bronchi
This is due to fibrous scarring after infection, or chronic obstruction
Which pathogen is most likely to cause Tb?
Mycobacterium tuberculosis
(M.bovis can also cause Tb)
What is a key sign of Tb?
Granuloma formation
Caseating ācheesyā necrosis
This is due to a delayed hypersensitivity (type IV) reaction
What is primary Tb?
The first exposure to Tb
The pathogen is phagocytosed and taken to hilar lymph nodes which provokes an immune reaction leading to a granulomatous response
What is secondary Tb?
This is a secondary encounter with Tb and involves reinfection and reactivation
A degree of immunity will be present
Generally the disease will still remain localised to the lung apices
Describe the tissue changes in primary Tb
Small focuses (Ghon focuses) occur which are small lesions caused by the mycobacterium
Large hilar nodes will develop due to the granulomas forming
Describe the tissue changes in secondary Tb
Fibrosis and cavitating of apical lesions will occur
This worsens the damage already present
Why may reactivation with Tb occur?
Decrease in T cell function due to:
- Age
- Immunosuppression due to disease (HIV)
- Immunosuppression due to therapy - steroids, chemo
How may a patient be diagnosed with Tb?
- History
- Broncho-alveolar lavage - bronchoscope is passed into the lungs and squirts fluid into the lungs which is subsequently collected for study
- Biopsy
What is the pulmonary interstitium
This is where gas exchange occurs
Contains alveolar type I and II cells as well as thin connective tissue high in elastin
How does ILD commence?
Any form of injury that leads to alveolitis - inflammation of the alveoli
What are the two umbrella causes for ILD?
- Environmental - minerals (asbestos), drugs, radiation
- Idiopathic
How can ILD be diagnosed?
- Transbronchial biopsy
- Thoracoscopic biopsy - more invasive - thoracoscope enters through an incision between ribs allowing for visual inspection of the lungs
What are some forms of ILD?
- Fibrosing alveolitis
- Sarcoidosis
- Extrinsic allergic alveolitis (hypersensitivity pneumonitis)
- Pneumoconiosis - occupational lung disease
- Connective tissue disease
What is fibrosing alveolitis?
A type of idiopathic pulmonary fibrosis
Inflammation is usually associated with the condition
Finger clubbing is a common symptom
What is the pathology of fibrosing alveolitis?
A sub-pleural and basal fibrosis occurs due to inflammation
In the terminal stages the lung structure becomes composed of large dilated spaces surrounded by fibrous walls - this is honeycombing
These thick walla and dilated spaces hinder gas exchange
What is extrinsic allergic alveolitis?
Chronic inflammation due to a type III and type IV hypersensitivity reaction
Airways become small and granulomas can be formed from collections of activated macrophages
What are some causes/forms of extrinsic allergic alveolitis?
- Thermophilic bacteria - Farmerās lung
- Avian proteins - Pigeon fancierās lung
- Fungi - Malt workerās lung
How can extrinsic allergic alveolitis diagnosed?
The presence of antibodies called precipitins can be detectable in the blood serum which indicate hypersensitivity reactions
Biopsies can be utilised to diagnose more difficult conditions
What is sarcidosis?
A multisystem granulomatous disorder commonly affecting the pulmonary system
In what ways can sarcoidosis manifest itself?
- Uveitis - inflammation of iris
- Erythema nodosum - inflammation of fat cells under the skin causing red patches
- Lympthadenopathy
- Hypercalcaemia
What effects can connective tissue diseases have on the pulmonary system?
- Interstitial fibrosis
- Pleural effusions
- Rheumatoid nodules - local swelling or lumps most often associated with rheumatoid arthritis
What is pneumoconiosis?
An umbrella term for ādust diseasesā
Characterised by inalation of ādustā, inflammation and fibrosis
What are three types of pneumoconiosis?
- Asbestosis
- Coal workerās lung
- Silicosis
What does the severity of pneumoconiosis depend on?
- Particle size (1-5microns) - larger get trapped, smaller can be breathed in and out
- Reactivity of particle
- Clearance of particle
- Host response
Asbestosis is a ________ and can have _________ (curved) or _________ (straight) fibres. Of the two, _________ fibres are far more dangerous
Silicate
Serpentine
Amphibole
Serpentine
What are consequences of asbestosis exposure?
- Parietial pleural plaques
- Interstitial fibrosis (asbestosis)
- Bronchial carcinoma
- Mesothelioma
What is pulmonary oedema?
Fluid build up in the lung interstitium
Pulmonary oedema is a type of __________ lung disease
Restrictive
What is the most common cause of pulmonary oedema?
Left ventricular heart failure and backflow pressure which causes the release of tissue fluid into the lungs
The heart cannot pump blood out of the lungs fast enough so pressure builds and fluid is deposited.
Why is pulmonary oedema bad for gas transfer?
By occupying space in the alveoli, the fluid increases the distance oxygen must diffuse to enter the blood stream so less oxygen will diffuse
This is not a problem for carbon dioxide to exit since it is 20 times more soluble than oxygen
What is ARDS?
Adult respiratory distress syndrome
What is the pathology of ARDS?
- Inflammatory cells enter a region of injury in the lungs due to bacterial endotoxin
- Cytokines are released
- Oxygen free radicals are released
- Collateral damage occurs to cell membranes due to the inflammatory response
ARDS can cause?
- Sepsis
- Severe trauma
How is ARDS characterised?
- Fibrous exudate lining alveolar walls
- Evidence of cell regeneration
- Inflammation
Why does neonatal RDS occur?
Premature infants produce inadequate surfactant between pleura
There is reduced surface tension and breathing is difficult and may cause damage to cells
What is an embolus?
A detached intravascular mass carried by the blood to a site in the body far from its origin
Emboli can be thrombi, gas, fat, foreign bodies or tumour
What is the source of most pulmonary emboli?
Deep venous thrombosis of the lower limbs
Virchowās triad describes the risk factors for developing a thrombus as with DVT for example, what is this triad?
- Stagnant blood flow
- Hypercoaguable blood
- Endothelial injury/abnormality
What is primary pulmonary hypertension?
This is hypertension due to abnormalities within the lungs
What is secondary pulmonary hypertension?
Hypertension associated with another condition such as emphysema, COPD, lupus etc
Primary pulmonary hypertension is most common in ________ ________
Young women
What is cor pulmonale?
This the alteration in the structure and or functio of the right ventricle due to a primary disorder of the respiratory system
Often this is due to primary hypertension
The pleural is lined with that type of epithelium?
Squamous
What are the two types of pleural effusion?
- Transudate - cardiac failure, low protein levels
- Exudate - high protein levels, Tb, pneumonia, malignancy, connective tissue disease
What is a purulent effusion?
An empyema
Tumours in the lungs can be of which two categories?
Primary - malignant mesothelioma, benign
Secondary - adenocarcinomas, undergone metastasis
Mesothelioma is characterised by _________ the lung by affecting all of the pleura
Surrounding
The differentiation of both __________ and ___________ cells are involved in mesothelioma
Epithelial
Mesenchymal
What is present under the ethmoid bone that is specialised for the sense of smell?
An area of olfactory epithelium
The vestibule of the nasal cavity is lined with what for protection?
Keratinised stratified squamous epithelium
Further into the nasal cavity, how does the epithelium change
It becomes respiratory epithelium
(pseudostratified ciliated columnar epithelium with goblet cells)
Where are basal cells located and what do they function to do?
Located at basal lamina and will replace epithelium - they are a type of stem cell
What is the lamina propria?
A thin layer of connective tissue below the epithelium to which it connects collectively becoming the mucosa
It contains seromucous glands
The oropharynx and epiglottis have which type of epithelium?
Respiratory epithelium without goblet cells
(Non-keritinised stratified squamous epithelium)
What epithelium coats the larynx?
The cartilage ad muscle is coated with respiratory epithelium
The vocal folds are coated in stratified squamous epithelium for strength due to vocal cord collisions during sound production
What is the carina?
The point of bifurcation of the trachea
What are seromucous glands?
Glands in which serous and mucous secretory cells are present
The walls of the trachea have what lining?
Respiratory epithelium
(with basal lamina and lamina propria - contains elastic fibres)
There is also a layer of submucosa containing seromucous glands
What is present within the bronchi that allows for the mucociliary rejection current?
Cilia
How does the cartilage in bronchi differ from that in the trachea?
Bronchi - irregularly shaped in plates
Trachea - āCā shaped
When is the transition from bronchi to bronchioles defined?
When there are no longer cartilage plates
The lamina propria in bronchioles is composed of what 3 main consititutes?
- Smooth muscle
- Elastic fibres
- Collageous fibres
What are terminal bronchioles?
The smallest bronchioles that still lack respiratory function
What is present down the bronchial tree after terminal bronchioles?
Respiratory bronchioles
What innervates the smooth muscle of bronchioles?
The parasympthetic nervous system
This can inititiate contraction
Terminal bronchial epithelia are lined with what types of cell?
Cuboidal ciliated epithelium and non-ciliated club cells (Clara cells)
Non-ciliated club cells have which roles?
- Stem cells
- Detoxification
- Immune modulation
- Surfactant production
Describe respiratory bronchiole walls
It is discountinous squamous epithelium with type 1 aveoli within their walls - as opposed to low cuboidal epithelium
What are pneumocytes?
Alveolar cells
Type 2 alveoli are covered in what?
Microvilli
The cytoplasm of type II alveoli contains what?
Lamellar bodies
(release surfactant by exocytosis)
What are dust cells?
Macrophages found in alveloli which remove pathogens and foreign material that bypasses the mucociliary escalator
