asthma Flashcards
what is asthma
chronic inflammation of the airways with airway hyperresponsiveness
which leads to episodes of airflow obstruction characterised by shortness of breath, wheezing, tightness of chest and coughing - episodes are most common at night or early morning
what is FEV1 testing
forced expiratory flow in 1 second - should be 70-80% of vital capacity
what happens during an asthma attack
muscles tighten around airways to constrict them
inflammation of lining shrinks passageway
excess mucus blocks airway
what causes contraction of smooth muscle
increase in intracelluar calcium triggers
myosin gets phosphorylated and interacts with actin
asthma risk factors can be decided into which two groups
host factors which cause the development of asthma
and environmental factors that trigger symptoms
what are the main host factors
gender, genetics and obesity
what are the main environmental factors
allergens, infections, smoke, air pollution and diet
why are females more likely to be affected by asthma after age 15-24 than males aged 15-24
pre puberty - boys have smaller airway diameter relative to lung volume
post puberty - girls have smaller airway diameter than boys - more likely to suffer from an airway limiting condition
progesterone is associated with down regulation of beta 2 adrenoreceptors
what is the link between obesity and asthma
asthma incidence is 50% higher in overweight or obese individuals
leptin is an obesity gene product, secreted by adipocytes - can stimulate the production of pro inflammatory mediators
leptin also high in asthma patients
what are mast cells
cells found abundantly in tissues forming interfaces with the external environment - release histamine during inflammatory and allergic reaction
what is EIA
exercise induced asthma - airway narrowing induced by exercise
what is EIB
exercise induced bronchospasm - reduction in lung function only after exercise even in absense of previous asthma diagnosis
different from asthma due to
- no inflammation
why is EIA worse in cold environments
as exercise intensity increases - more oxygen required - more breathing through mouth - air is less moist - irritation of airway
in cold environment - air is cold and dry
irritation of airway - bronchoconstriction and inflammation
what are the two main drugs used for asthma treatment
beta 2 agonists - act on beta 2 receptors of smooth muscle and cause relaxation of the airways
anti - inflammatory drugs - corticosteroids , used for long term reduction in asthma related inflammation and hence severity of symptoms
how can exercise affect asthma
exercise associated release of adrenaline/noradrenaline - relaxation of the bronchial tree
exercise may reduce adipose tissue which reduced leptin which reduces inflammation
