Lung cell biology Flashcards
(40 cards)
What are the divisions of the airways`
0 Trachea 1 bronchi 4 bronchioles 14 terminal bronchioles 15 transitional bronchioles 16 respiratory bronchioles 19 alveolar ducts 23 alveolar sacs
What is epithelium?
Forms continous barrer isolating extenral from internal
Produces secretions to protect cells and reduce surface tension
Metabolise foreign and host derived compounds
Release mediators
Trigger lung repair process
Where are goblet cells found?
Large, small, airways
What percentage of epithelial cells are goblet cells?
In healthy lung 20% of epithelial cells
What is the effect of smoking on goblet cell numbers
(at least doubles in smokers, thicker and increased secretions, more viscoelastic)
What is the function of goblet cells?
Traps smoke carticles and trap and harour microporganisms isncreaisng chance of infection
Sythesisze and secrete mucus
‘thin’ sol phase overlays cells, thick gel phase at air interface.
What does the mucus in goblet cells contain?
Mucin proteins, proteoglycans and gycosaminoglycans,
Give mucus viscoelasticity
What combats microorgsnisms and phagocyte roteases in mucus?
albumin and alpha 1-antitrypsin, also called alpha 1-proteinase inhibitor,
Inhibit polymorphonuclear neutrophil proteases
What combats inhaled oxidants?
Antioxidants from the blood and synthesised by epithelial cells and phagocytes – uric acid and ascorbic acid (blood), glutathione (cells)
Where are cilia found
- Large, central, small airwas,
What proportion of epithelial cells is cilia?
- 80% of epithelial cells
How do cilia beat?
- Beat metasynchroulsy
- Tips of cilia in sol phase of mucus pushes mucus towards epiglottis
- Expectorated
How does smoking affect cilia?
- Depleted in smokers with bronchitis
- Asynchrous
- Found in bronchioles which blocks smaller airways
- Unable to transort thickeend mucus
- Reduced musuc clearance
How are smaller airways held open?
- Intact alveolar walls hold airways open
Where are Clara cells found?
- Mosdt conducting and transitional airways
- Increase in proportion distally e.g bronchi and bronchioles
What is the function of Clara cells?
- Xenobiotic metabolism
- Metablism of foreign compounds deposited by inhallation
What are phase I and phase 2 enzymes?
Phase 1: cytocrhome P450 oxidases
- Metabolise foeigh compounds
- Enables phase 2 enzymes to neutralise toxic aganet
- May often activate precarcinogen to carcinogen
Phase 2: glutathione S-transferase
- Enables conjugation of BPDE to small molcule
- Neutralises it’s activtiy
- Some don’t have it
- If also smoker may increase
What else do phase 1 and phase 2 enzymes secrete?
- Lots of proteases
- Lysosyme
- Antioxidants
What is the normal ratio of Type 1 to Type 2 cells?
1:2
Less type 1 in smokers
What is the function of type 2 epithelial cells?
- Synthesise and secrete pulmonary surfactant ( immunological functions)
- Precursor of alveolar epithelial type I cells. Divide and differentiate to replace damaged type I cells.
- Synthesise and secrete anti-proteases
- Found in alveoli
- Carry out xenobiotic metabolism
What is the funciton of type 1 epithelial cells?
thin but strong to allow gas exchange
(95%) of alveolar surface
How are carcinogens made in the lungs?
- Smoke contains procarcinogens
- Club cells, type 2 cells, macrophagesc ontain phase 2 and phase 2 enzymes used in detoxification
- Lung cells contain hase 1 enzymes which activste compound
- Compound becomes more carcinogenic,
- Phase 2 enzymes make them water soluble and they are exreted
- If more carcinogens than phase 2 enzymes can deal with you get DNA binding, adduct formtion, no repair and mutation
What a proportion of lungs is alveolar macrophages in a normal person and in a smoker ?
90% of phagocytic cells
Increase 5-10x in smoker
What is the role of alveolar macrophages?
- phagocytose debris and microorganisms.
- Use cytokines to recruit pro inflammatory cells and molecules
- proteases to digest unwanted debris, attack organic material
- oxidants during phagocytosis and on activation to kill infecting organisms etc
- antioxidants such as glutathione to neutralise oxidative molecules that might be inhaled or generated during infection etc
- Contain enzymes that metabolise toxicants (xenobiotic metabolism)
