13. Lung and the Environment Flashcards
a few forces that control particle deposition in the lungs
- inertia/impaction: tendency to fail to turn corners of R tract, impact upon nose, pharynx, bifurcations
- sedimentation: particles settle acc to their weight
- diffusion (random movement)
characteristics that modify particle deposition?
- breathing pattern
- anatomy of the resp tract
a few defense mechanisms we have against inhaled substances?
- physical barriers (ie nose filtration)
- mucociliary clearance
- alveolar clearance
- cough
- immune system
describe mucociliary clearance
active from resp bronchiole to larynx. coordinated activity of ciliated epithelium. epit cells covered with a fluid bilayer, with both solution phase and gel phase. sol phase facilitates ciliary beat.
how quickly do most normal people clear inhaled particles from the bronchi?
6 hrs
what phase of mucociliary clearance does cystic fibrosis disrupt (sol or gel)?
sol
what phase of mucociliary clearance does chronic bronchitis disrupt (sol or gel)?
gel
what phase of mucociliary clearance does Kartagener’s syndrome disrupt?
cilia
describe alveolar clearance
non ciliated regions. particles transported by alveolar macrophages to mucociliary laler of lymphatic system.
what does the ability to cough depend on?
the presence of intact upper and lower afferents and reflex efferents, resp muscles, larynx
what are some examples of diseases caused by inspired substances?
silicosis, coal worker’s pneumoconiosis, asbestos-related lung disease, farmer’s lung, malt worker’s lung
where does asbestos exposure occur?
mining, home insulation, production of fireproof textiles, paints, brake and clutch linings
what usually occurs with inorganic dust diseases (pneumoconiosis)?
parenchymal inflammation, fibrosis due to the tissue reactions involved in trying to clear organic dusts
besides interstitial fibrosis, another major lung disease that people exposed to asbestos can present with?
cancer. smoking + asbestos exposure together is terrible.
what is organic dust disease? what are the 2 types of immune responses it causes?
hypersensitivity.
two types:
-hypersensitivity pneumonitis (ex farmer’s lung)
-occupational asthma (ex cereal worker’s lung)
Features of hypersensitivity pneumonitis?
systemic reaction, fever, crackles, restrictive pattern.
Features of occupational asthma?
dyspnea/wheezing at work, may have latent period of several hours. cough, sputum may improve weekends and vacations.
what is aspiration?
normal people aspirate frequently. clinical meaning of aspiration is inhaling a usually non-respirable particle with subsequent disease
what are 2 mechanisms of aspiration?
- impaired neuromotor function (anesthesia, depressed lungs, alcohol)
- altered anatomy
what is the difference between mainstream and sidestream smoke?
mainstream produced when smoker draws on cig. predominant source for smoker.
sidestream = when cig smolders. predominant env source
what does nicotine do in the body?
binds to acetylcholine receptors at autonomic ganglia, adrenal medulla, NM junction and brain.
what are the effects of nicotine in the body?
stimulates hormone release: catecholamines, ACTH.
inc heart rate, BP, CO
mental stimulation, relaxation, enhanced learning, memory, attention.
promotes thrombosis, plate agg and vasospasm
what % of americans smoke?
23%
what cancers does smoking contribute to?
lung, also oral cav, larynx, esophagus, bladder, kidney, panc, stomach, cervix
what cardiac problems are caused by smoking?
atherosclerosis, incl coronary artery disease, CV disease, peripheral vasc disease
what main resp diseases are caused by smoking?
COPD (chron bron, emphy)
definition of invol smoking?
exposure of non-smokers to tobacco combustion products in the indoor envt
chronic effects of invol smoking in children?
freq of acute resp illness (asthma, chronic cough, sputum, wheezing) in children 5-20 yo
effect of parental smoking on kids asthma?
increased incidence
smoking cess programs long-term success rate is approx what %?
20%
4 benefits of smoking cessation
- inc life expectancy
- slowing of progression of tobacco related disease
- decr risk of lung cancer
- reduction in perioperative resp complications
water soluble agents: where do they do damage?
they dissolve in upper resp tract. injure immediate air spaces (nose, throat, bronchi).
water insoluble agents: where do they do damage?
more distal, alveoli, bronchioli
water insoluble agents: why delay in recognition?
lack of deposition on mucosal surfaces. symptoms delayed 3-30 hrs
factors affecting particle deposition
- impaction
- sedimentation
- diffusion
why do we advise people taking inhalers to inhale slowly?
to minimize impaction. also they hold their breath afterwards to allow time for sedimentation (so they don’t exhale the med)
what is relevant about Kartagener’s syndrome?
structural abnormality of cilia
definition of pneumoconiosis?
lung disease caused by inhalation of inorganic dusts
what is silicosis?
one type of pneumoconiosis.
Lung disease secondary to inhalation of silicon dioxide
2 types of silicosis?
Simple silicosis: generally a radiographic abnormality (nodules), unaccompanied by change in lung function, impairment or disability, or decreased longevity
Progressive massive fibrosis: formation of large, coalescent masses that obliterate lung structure
coal worker’s pneumoconiosis: difference from silicosis?
only difference is type of dust. CWP may present mosaic. nodules, focal emphysema
definition of asbestosis?
interstitial lung disease associated with asbestos exposure. may yield a pleural plaque (plates of calcium at lung border on cxr)
definition of hypersensitivity pneumonitis?
Immunologically mediated lung disease (secondary to inhaled organic dust)
Caused by intense and/or repeated exposure of dusts that reach distal lung units
Same clinical and pathologic findings regardless of organic dust involved
Acute exposure: flu-like symptoms + breathlessness within hours
Chronic exposure: insidious onset of respiratory symptoms, possibly with irreversible fibrosis
a few causes of hypersensitivity pneumonitis?
Malt worker’s disease
Farmer’s Lung
Tea grower’s disease
a few causes of occupational asthma?
cereal dust
wood dust
animal proteins
what drugs are best to support smoking cessation?
- varenicline
- Partial agonist for α4β2 nicotinic acetylcholine receptor which may play a role in addiction
- more successful than buproprion or placebo
