Respiratory Histopathology Flashcards
What is the conducting system of the respiratory system?
- airways starting at nasal cavity - ends at terminal bronchioles
What is the respiratory zone of the respiratory system?
- starts at respiratory bronchioles - ends at the alveoli sacs
What are the 3 main functions of the conducting system that they must ensure happens to air in the respiratory system?
- clean air - warm air - protect airways
What cells lines the conducting system of the respiratory system?
- pseudostratified ciliated columnar epithelial cells
Pseudostratified ciliated columnar epithelial cells line the membranes of the conducting system of the respiratory system, but what fills the rest of the airways?
- lamina propria - made of loose connective tissue
Pseudostratified ciliated columnar epithelial cells line the membranes supported by loose connective tissue called the lamina propria in the conducting system of the respiratory system, but what are the other 3 main aspects found within the lamina propria?
- blood vessels
- mucous glands
- serous glands
What do serous glands secrete in conducting system of the respiratory system?
- proteins in a less viscous solution than mucous glands
What is the muscociliary escalator?
- interplay between mucous and ciliary in airways - remove debris, pathogens etc… - can be damaged in lung disease
Where is the Olfactory Epithelium located?
- in the roof of the nasal cavity
- olfactory = means smell
Sustentacular cells line the Olfactory Epithelium, what are Sustentacular cells?
- a form of epithelial cell
- act as metabolic and structural support
What is the terminal bar in the Olfactory Epithelium?
- junctional complex connecting adjacent epithelial cells on the lateral surface
- examples include zonula occludens and zonula adherens
What is a Bowmans gland located in the Olfactory Epithelium?
- mucosubstance secreting gland
- secrete mucous or serrous fluid
- secretes onto luminal/apical surface of the olfactory epithelium
What are the basal cells of the Olfactory Epithelium?
- epithelial basal cells
- able to differentiate into sustentacular or olfactory cells
What is the purpose of the sustentacular cells microvillia located in the Olfactory Epithelium?
- increase surface are of the Olfactory Epithelium
- they hold onto smell molecules until can bind with olefactory cilia
- microvillia like in the GIT, but here they are motile
What are the olfactory receptor cells of the Olfactory Epithelium?
- form of epithelial cell
- capable of binding odour molecules involved in smell
What is the end of the olfactory receptor cells inside the olfactory epithelium called?
- olfactory knob
- attaches to nerve fibres
What is the name given to the cilia located at the end of the olfactory receptor cells facing the lumen of the nasal cavity?
- olfactory cilia that bind odur molecules
- non motile
What are the 3 major parts of the olfactory receptor cells, beginning with the basal side of the cell?
1 - olfactory receptor cell
2 - olfactory knob
3 - olfactory cilia (attached to olfactory knob)
What is special about the end of the olfactory receptor cells based in the basal aspects of the cell?
- attached to olfactory bulb
- olfactory bulb attached to olfactory nerve fibres
- provide information to brain about smell
Where in the lungs does gas exchange take place?
- anywhere beyond the terminal bronchioles
What are Clara cells?
- form of epithelial cell
- non ciliated cells
- act as a stem cell
Where are Clara cells generally found?
- distal respiratory bronchioles
- terminal and respiratory bronchioles
What 2 things do Clare cells secrete?
- part of surfactant
- enzymes able to detoxify noxious substances
What are the 3 main components of the alveoli?
1 - single layer of epithelial cells
2 - supporting tissue (elastic+collagenous fibres and the occasional fibroblast)
3 - blood vessels
What are pneuomcytes?
- pneumo = lungs - cells of the alveoli
What are the 2 types of pneuomcytes of the alveoli?
- type 1 = squamous epithelial cells acting as a barrier
- type 2 = cuboidal epithelial cells secreting surfactant
Are there more type 1 or 2 pneuomcytes in the alveoli?
- type 1, but type 2 are a lot bigger
What are the pores of Kohn?
- holes in adjacent alveoli - connection between alveoli
What are the benefits of the pores of Kohn?
- allow air to move between alveoli - maintain homeostasis
What are the risks of the pores of Kohn?
- allow infection spread between alveoli
What term is used to describe patients who are prone to the triad of asthma, eczema and hayfever?
- atopic
What does paroxysmal mean?
- sudden short attacks of a symptom or condition
What is the main cause of COPD?
- smoking
What is chronic bronchitis?
- chronic irritation of bronchial mucosa
What is the clinical diagnosis of chronic bronchitis?
- sputum production most days
- >3months for 2 consecutive years
In chronic bronchitis what happens to the bronchial mucosa?
- becomes thickened
- form of COPD so obstructive lung disease
What are some common causes of chronic irritation involved in chronic bronchitis?
- smoking (main cause)
- pollutants
- recurrent infection
What are the most common changes to the bronchi in chronic bronchitis and chronic asthma?
- inflammatory cells infiltrate submucosa
- hypertrophy of smooth muscle
- mucosal cell hyperplasia and ⬆️ mucus production
- squamous cells metaplasia (columnar change to sqaumous)
What is emphysema?
- chronic irritation and inflammation of respiratory zone
- permanent enlargement of respiratory zone
- form of COPD
How does emphysema cause a permanent enlargement of the respiratory zone?
- alveoli can collapse, narrow and generally not function
- ⬇️ surface area
- air sacs merge and form bullae
What is pulmonary fibrosis?
- scarring of the lungs
- restrictive lung disease
What happens to the alveolar walls in pulmonary fibrosis?
- ⬆️ thickness due to collagen deposition
- ⬆️ fibrosis
- ⬆️ in type 2 pneuomcytes
What is pneumoconioses, also known as occupational lung disease?
- interstitial lung damage caused by irritants
- generally inorganic dusts
- can cause fibrosis
What does pneumoconioses, also known as occupational lung disease do to the interstitial aspects of the lungs?
- fibrosis in lungs
- ⬆️ thickness of interstitial space
- ⬇️ perfusion
Silica dust has been shown to cause pneumoconioses, also known as occupational lung disease. What happens to the macrophages in patients who inhale silica dust for long periods?
- phagocytosed by macrophages
- formation of granuloma like masses around macrophage containing silica
- macrophages containing silica induce fibrotic reactions
- nodules form of collagenous tissue
Why is asbestos so dangerous?
- small like fibres can enter airways
- coated with proteinaceous material forming asbestos bodies
- macrophages and giant cells infiltrate and cause fibrosis
What is the most common cancer in patients exposed to long term asbestos?
- mesothelioma
What are the 2 groups of lung cancer/neoplasms?
- small cell lung carcinoma
- non-small cell lung carcinoma
What % of lung cancer/neoplasms are caused by - small cell lung carcinoma and non-small cell lung carcinoma?
- small cell lung carcinoma = 20%
- non-small cell lung carcinoma = 80%
What are the 3 subdivisions of non-small cell lung carcinoma?
1 - squamous cell carcinoma
2 - adenocarcinoma
3 - large cell carcinoma
Are benign tumours in the lungs common?
- no
- they are rare
What cells do small cell lung carcinomas generally originate from?
- neuroendocrine cells that differentiate
On histology how do small cell lung carcinomas appear?
- darkly stained
- crushed and tightly packed together
Is small cell lung carcinomas responsive to treatment?
- yes
- generally too late to treat when diagnosed though
- highly malignant and metastasised
Squamous cell carcinomas are a form of non-small cell lung carcinomas, where do they generally start?
- affect squamous cells
- main bronchi
