Lung Cell Biology Flashcards
Is the terminal bronchus cartilaginous or non-cartilaginous?
What keeps them open?
non-cartilaginous
Surfactant on the inside of the terminal bronchiole or alveolar attchments keep it open.
The cross sectional area of the lung increases ……………………..
The cross sectional area of the lung increases peripherally
List 5 roles of the epithelium
Role of the Epithelium
Forms a continuous barrier, isolating external environment from host
Produces secretions to facilitate clearance, via mucociliary escalator, and protect underlying cells as well as maintain reduced surface tension (in the alveoli)
Metabolises foreign and host-derived compounds
Release mediators (controls the number of inflammatory mediators that reach the lungs)
Triggers lung repair processes
List the type of epithelial cells found in the lungs and state their roles?
Type I cells cover most of the alveolar surface area, gas exchange takes place through these cells, which here can be seen wrapped around the underlying capillaries.
Type II cells synthesise and release the lung lining liquid, which includes lung surfactant, which prevents the lungs from collapsing at low pressure, on exhalation
In the image below the type 1 cell is so thin that the groves are actually blood vessels. Type1 cell is like silk and the blood vessels are like rods.
Draw a simple diagram of how the airways increase in surface area peripherally
Alveoli
In susceptible smokers,…………….. in the alveoli may appear and the alveoli may become larger
This leads to a reduction in the ……………… ……………… available for gas exchange
This can be seen as ……………… ……………… loss - therefore, expansion during breathing is reduced which increases the amount of ……………… ………………
Alveolar walls consist of TWO types of epithelial cell: ……………… and ……………..
Type II cells are ……………… susceptible to damage than Type I cells but Type I cells are ……………… more often
Type II cells - also called Type II ……………… are found only in the alveoli (covers 5% of the alveolar surface)
Contain ……………… ……………… that store surfactant prior to release onto the air-liquid interface
Surfactant is a ……………… rich surface active material that prevents lung ……………… on expiration and has immunological functions
Synthesise and secrete ………………
Positioned in the corners of the alveoli and are embedded in the interstitium with the apical membranes facing the air
Type II cells are very close to capillaries
Type II cells are a precursor for alveolar epithelial ……………… cells - they divide and differentiate to replace damaged ……………… cells
Alveoli
In susceptible smokers, holes in the alveoli may appear and the alveoli may become larger
This leads to a reduction in the surface area available for gas exchange
This can be seen as elastic tissue loss - therefore, expansion during breathing is reduced which increases the amount of dead space
Alveolar walls consist of TWO types of epithelial cell: Type I and Type II
Type II cells are more susceptible to damage than Type I cells but Type I cells are damaged more often
Type II cells - also called Type II Pneumocytes are found only in the alveoli (covers 5% of the alveolar surface)
Contain lamellar bodies that store surfactant prior to release onto the air-liquid interface
Surfactant is a phospholipid rich surface active material that prevents lung collapse on expiration and has immunological functions
Synthesise and secrete antiproteases
Positioned in the corners of the alveoli and are embedded in the interstitium with the apical membranes facing the air
Type II cells are very close to capillaries
Type II cells are a precursor for alveolar epithelial type I cells - they divide and differentiate to replace damaged type I cells
What do Type II cells contain and what do they store?
What is surfactant rich in and what does it prevent?
What does it synthesise and secreate?
Where are they very close to?
What are they a precursor for?
Type II cells - also called Type II Pneumocytes are found only in the alveoli (covers 5% of the alveolar surface)
Contain lamellar bodies that store surfactant prior to release onto the air-liquid interface
Surfactant is a phospholipid rich surface active material that prevents lung collapse on expiration and has immunological functions
Synthesise and secrete antiproteases
Positioned in the corners of the alveoli and are embedded in the interstitium with the apical membranes facing the air
Type II cells are very close to capillaries
Type II cells are a precursor for alveolar epithelial type I cells - they divide and differentiate to replace damaged type I cells
TYPE II CELLS SYNTHESISE AND RELEASE …………………… TO PREVENT ALVEOLAR COLLAPSE ON EXPIRATION
TYPE II CELLS SYNTHESISE AND RELEASE SURFACTANT TO PREVENT ALVEOLAR COLLAPSE ON EXPIRATION
Secreted surfactant ………………. across the alveolar epithelial surface; “unused” surfactant is stored in the corners of the alveolus as …………….. ……………….
Secreted surfactant spreads across the alveolar epithelial surface; “unused” surfactant is stored in the corners of the alveolus as tubular myelin
Surfactant contains:
10% ……………….. This fraction contains the surfactant-associated proteins that are important in ………………… and activity of surfactant
90% …………., of which 90% is …………………...
The phospholipid has lipophilic and hydrophilic regions and is therefore ………………., enabling polarisation at the epithelial surface and surface tension reducing activity.
Surfactant contains:
10% protein. This fraction contains the surfactant-associated proteins that are important in spreading and activity of surfactant
90% lipid, of which 90% is phospholipid.
The phospholipid has lipophilic and hydrophilic regions and is therefore amphipathic, enabling polarisation at the epithelial surface and surface tension reducing activity.
What are the 3 main structures of lung blood vessels
Top left smokers emphysema, top right alpha 1 antitrypsin deficient emphysema.
Bottom showing advanced emphysema where attempted repair leads to some fibrosis, holes too big to provide adequate gas exchange
How do type II cells contribute to fibrosis of lung tissue
Showing showing how type II cells multiply to repair damaged alveolar epithelium but also produce too much surfactant, and stimulate fibroblasts to produce connective tissue. Gas exchange becomes impossible
Too much surfactant can be damaging, instead of a nice thin layer for gas exchange now you have a thick layer which makes gas exchange difficult.
Idiopathic fibrosis, no known cause, but similar deposition of lots of collagen and thickening of alveolar walls,
Endotoxic shock, which occurs in acute lung injury due to sepsis. Shows early eodema
The oedema has taken the capillary away from the alveolus reducing the efficancy of gas exhange
Shows alveolar epithelial type I cell injury- reduce efficancy of gas exchange due to it becoming thicker
Hayline membrane gets layed down during respiratory distress. Hayline is greek for glassy. So you get this glassy membrane being layed down which is quite inpentrable so it is difficult for oxygen and co2 to pass through.
Summary
