respiratory cell biology Flashcards
respiratory cell biology: recall the structure, location and function of the principle cells of the airways, including epithelial cells, goblet cells, type 1 pneumocyte, type 2 pneumocyte, alveolar macrophage, smooth muscle cells, interstitial cells and Clara cells (non-ciliated secretory epithelial cells, also termed Club cells)
purpose of folding round of tubules
surface area massive in small space
cross sectional area increases peripherally - 23 generations
diagram from slide 5
5 functions of entire epithelium
forms continuous barrier, produces secretions to facilitate clearance and protect undelying cells and maintain surface tension, metabolises foreign and host-derived compounds, releases mediators, triggers lung repair process
goblet cells: type of cell and abundance in types of airways
polarised columnar cells; more in large, then central, then small airways surrounded by stratified squamous
goblet cells: % of epithelial cells
20% of epithelial cells
goblet cells: function
synthesise, store and secrete mucus via apical membrane
ciliated epithelial cells: type of cell and abundance in types of airways
ciliated; more in large, then central, then small airways
ciliated cells: % of epithelial cells
60-80% of epithelial cells
ciliated cells: name given to type of beat
monochronal (metasynchronous)
club cells: location, % and type of cell
rich in bronchiolar regions; 20% small airway epithelia; non-ciliated secretory cells
club cells: function
contain secretory granules with detoxifying enzymes; protect bronchiolar epithelium, act as repair or progenitor cells, replace damaged epithelium, produce secretions for xenobiotic metabolism
function of type 1 pneumocyte
fascilitates gas exchange and solute transport across alveoli
properties and abundance of type 1 and 2 pneumocytes
type 1: very thin so covers most of lung surface (95%); type 2: 5% surface
function of type 2 pneumocyte
contain lamellar bodies for storing surfactant, which they sythesise and secrete - maintains surface tension; act as progenitor cells (precursor of type 1); some detoxification
ratio of type 1: type 2 pneumocytes
1:2 (twice as many type 2 pneumocytes as type 1)
location and function of stromal cells (myofibroblasts; interstitial cells)
subepithelially in mucosal surfaces; deposit ECM to give elasticity and compliance (elastin and collagen); divide to repair
functions of all secretory cells (goblet, club, type II)
secrete protective lining layer to trap deposited particles; surfactant and mucus, synthesise and release antioxidants e.g. glutathione, superoxide dismutase; synthesise and secrete antiproteinases e.g. secretory leukoproteinase inhibitor (SLPI); release lysosyme; carry out xenobiotic metabolism (e.g. process and detoxify
foreign compounds such as carcinogens in cigarette smoke); contain cytochrome P450, phase I and II enzymes etc
what do phase I enzymes do
convert procarcinogen to carcinogen in lung
what do phase II enzymes do
normally make them water soluble and excreted in metabolite, but if pathway overload or inactivated causes DNA binding, adduct formation and no repair so mutation
airway smooth muscle functions
structure, tone (airway calibre - contraction and relaxation)
what is mucin stored in as a condensed form
mucin granules in goblet cells
what do ciliated cells have and why
high mitochondria to ensure beating
what happens when mucin secreted
mucin takes on water and expands massively
what are functional mucus secreting units called and where do they secrete mucus
acini, into collecting duct
where are serous acini located in relation to mucus acini and what is their function
serous acini deeper secrete antibacterials (e.g. lysozyme - more water based); wash mucus into collecting duct
ciliary structure
apical hooks, rods slide over each other to allow movement; 9+2 arrangement
define metachronal rhythm
layer of mucus; leading edge; field of cilia will move leading edge a little way along; cilia then move back and waft again after other cilia have moved
define mucus flakes
so much mucus can’t see cilia
