resp cell biology Flashcards
describe the epithelium
goblet cells
many mt - for cilia to beat
ciliated cells
continuous barrier - isolate from external, protection
list the functions of the epithelium
secretion of mucins, water and electrolytes
mucous is to trap and remove microbes and particulates
mucocillary clearance
proteins in secretions - maintain reduced surface tension
metabolise foreign and host derived compounds - xenobiotic
physical barrier
trigger lung repair process
make:
NO from NOS - speed cilia up
CO by hemeoxygenase - theory: kill bacteria
arachidonic acid metabolites - prostaglandins
chemokines eg IL 8
cytokines - GM-CSF
proteases
inf mediators
release of mucous
mucin tightly packed in goblet cells
when released - hit water = expands
submucosal glands made of acini - secrete mucous into collecting duct - wafted onto surface
human bronchial gland: mucous acini, serous acini - antibacterials and more watery
glands secrete water and salts
serous secretion help wash mucous into collecting duct and onto the airway surface
mucocillary escalator
cilia beat in a metachronal way
the first group of cilia push the leading edge of the mucous
it is then pushed by subsequent cilia and the front cilia push the next section of the mucous
the cilia don’t actually move position.
highly synchronised
recall the role of alveolar macrophages
reach out to particles
take up particles
lots of macrophages accumulate around 1 asbestos fibre
where are polymorphonucelar neutrophils present
when present it is an infection
normally in smaller numbers than macrophages
roles of macrophages and neutrophils
phagocytosis
antimicrobial defence
synthesise antioxidants eg glutathione
xenobiotic metabolism
effect of smoking on macrophages and neutrophils
increase the number 10 fold
in smokers with respiratory infection - neutrophil increase from 10-30% in respiratory units
in smokers ratio of macrophages:neutrophils from 70%:30% to 30%;70% - number of both cells increased, neutrophils more because of bacteria
what do neutrophils and macrophages release
serine proteases - neutrophil elastase
metalloproteinases- MMp9, Zn/metal reactive at site - dissolve own lung
effect of proteinases from neutrophils and macrophages
substrates - proteins, connective tissue, elastin, collagen
activate other proteinases- eg NE degrade and activate MMP
inactivate antiproteinases - eg NE degrade a-1 antitrypsin
activate cytokines and pro-inf mediators
neutrophil and macrophage releasing antioxidants
antimicrobial
generate reactive peroxides
inactivate a-1 antitrypsin
fragment connective tissue
mediators released by macrophages
help repair wounded tissue
chemoattractant/cytokines - IL8 - attract more inf cells in infection or acter toxicant/microbial deposition/inhalation
GF and proteases - trigger growth and repair by cells eg epithelium/stromal fibroblasts
function of the airways
conduit for O2 to alveoli and CO2 to lungs
for GE
3 things that allow airways to perform their functions
mechanical stability - cartilage
control of calibre - sm
protection and cleansing
organisation of airway structures
C shaped cartilage - slightly offset for tensile strength
submucosal gland - tip in SM - when contract mucus squeexzed onto surface
mucous inside lumen- 10ml, thinly spread
lumen
cilia
have radial spokes and rods that go up and down
inner and outer arms slide over each other - go back and forwards
some cilia move in 1 dirn, others in the other
apical hooks that engage with mucous
9+2 arrangement
200 per ciliated cell
60-80% epithelial cells
shorter in small airways
smooth muscle cells
contract and relax
involved in structure - hypertrophy and proliferation
secretion - mediators, cytokines, chemokines
smooth muscle cells with inflammation
hypertrophic
make NO and prostaglandins
make cytokines, chemokines and adhesion molecules- cause inflammatory cell recruitment
vasculature structure
trachea-bronchial circulation
systemic
perfusion 2nd to none
arteries from aorta, intercostal arteries and others
systemic veins to tracheal circulation
return to heart by bronchial and pul veins
plexus below the epithelium
good circulation so no need for pul circulation
Tracheo-bronchial circulation: functions
GE warm air humidification of air clears inf mediators clears inhaled drugs supply lumen with inf cells and proteinaceous plasma
describe plasma exudation
post capillary venules are leaky - leak plasma
C fibre nerve stimulates more holes
inf mediators histamine, PAF make more leaky
see this by using evans blue dye which binds to albumin and histamine - fluoresce orange
goblet cells
chalice shape bulge into lumen produce mucin 20% of epithelial cells in large airway
club cells
have secretory granules
detoxifying enzymes - destroy xenobiotics
repair damaged endothelium
in small airways - bronchiolar
type 1 epithelial cell
covers 95% alveoli surface
flat and thin - GE , and solute transport back and forth
type 2 epithelial cell
tiny and cuboidal
in corners of alveoli, in interstitium with apices facing the air
double number than type 1
secretory - make surfactant - release onto air-liquid interface
contain lamina bodies that store the surfactant - released when lung stretch
stem cell - divide into type 1
stromal cells myofibroblasts
make ECM - that cells sit on
made of collagen, elastin = elasticity and compliance
divide to repair
when overdrive = interstitial pulmonary fibrosis
function of secretory epithelial cells
secrete mucous and surfactant
release antioxidants - glutathione, superoxide mutase
secrete antiproteinases - secretory antiproteinase inhibitor (SPLI) - local - back up a 1 antitrypsin
release lysozyme - destroy bacterial cell wall
xenobiotic metabolism
contain chromosome P450, phase 1 and 2 enzymes
phase 1 and 2 enzymes
in club cells, type 2 cells and macrophages
involved in xenobiotic metabolism and detoxification
cigarette smoke and enzymes
procarcinogen
lung cell: phase 1 enz
phase 2 enz - normal: metabolism - make water soluble and metabolite is excreted
phase 2 enz - overload from phase 1 - no met - DNA binding, adduct formation, no repair = mutation
precursor for cancer
identifying cells
use receptor on the cell surface, cell signalling, to isolate cells from lungs at different stages
