Asthma intro Flashcards
Asthma definition
reversible increases in airway resistance, involving bronchoconstriction and inflammation
Characteristics of asthma
reversible decreases in FEV1:FVC
variations in PEF which improve with β2 agonist
decreases in FEV1, reversed by β2 agonist
What is COPD
chronic obstructive pulmonary disease
blanket term for chronic bronchitis and emphysema
obstructed airflow form the lungs
Chronic bronchitis
increased mucus, airway obstruction, intercurrent infections, airways permanently narrowed
Characteristics of COPD
FEV1 reduced, difficult to reverse
little variation in PEF
Clinical features of asthma
wheezing
SoB
tight chest
cough (chronic, worse at night/exercise)
What would be seen on a normal and asthmatic lung function test graph?
y axis: volume (L)
x axis: time (s)
normal - steep increase, plateau
asthma - steep increase which begins to plateau sooner but gradually rises to same level of normal line
Cause of asthma symptoms
stimulus causes mast cells and mononuclear cells in the lungs to release mediators:
spasmogens - immediate, bronchospasms
chemotaxins - later phase, inflammation
Examples of spasmogens
histamine
from arachidonic acid in the membrane: leukotrienes and prostaglandins
platelet activating factor
Examples of chemotaxins
leukotriene B4, PAF
What do chemotaxins do?
attract leukocytes (especially eosinophils and mononuclear cells) to lungs causes inflammation and airway hyper-reactivity
Types of medication to treat asthma
- bronchodilators - ‘relievers’
2. preventers - may be anti-inflammatory
Preferred short acting bronchodilator
salbutamol (Ventolin)
β2-adrenoceptor agonist
Action of salbutamol
bind to β2-adrenoceptors on smooth muscle
adenyl cyclase -> cAMP
relaxation
Effect of salbutamol
short acting
reduces parasympathetic activity
increases FEV1
prolonged use may lead to receptor down-regulation
What is a LABA?
long acting β agonist
eg. salmeterol
given for long-term prevention and control (ie.overnight)
preventer