Asthma Flashcards
Asthma
Reversible increases in airway resistance, involving bronchoconstriction and inflammation
What ratio can be used to characterise asthma; what values
reversible decreases in FEV1:FVC
forced expiratory volume in one second : Forced vital capacity
Can Asthma be Lethal
Yes
What variations can be used to diagnose asthma
Variations in PEF (peak expiratory flow) which improve with a B2 agonist indicate asthma
Symptoms of Chronic Bronchitis
Increased mucous, airway obstruction, intercurrent infection
COPD, most common cause, quantitative value used to indicate it
Chronic Obstructive Pulmonary Disease
Some combination of chronic bronchitis and emphysema
> 90% smoking related
FEV1 reduced
Sympathetic control of bronchial calibre
Circulating adrenaline acts on β2 adrenoceptors on bronchial smooth muscles to cause relaxation
(top most important)
sympathetic respose reduces parasympathetic involvement by releasing noradrenaline, inhibitng their transmission
additionally act on β2 adrenoceptors on mucous glands to inhibit secretion
Parasympathetic control of bronchial calibre
Acetyl choline acts on the muscarinic M3-receptors to cause bronchoconstriction and increasing mucous productoin
Factors that predispose asthma attacks
Allergens Cold air Viral infections Smoking Exercise
Clinical features of asthma
Wheezing
Acute onset of Breathlessness
Tight Chest
Cough (worse at night/exercise) (Nocturnal in kids)
Decreases in FEV1 reversed by a B2 agonist
Lung Function Test results (FEV1 vs FVC) graph for normal vs asthamtic patient
Biological response during asthmatic attack
How does PEF Change during an asthmatic attack (Early and late phase)
**This can vary a lot in clinical presentation with both phases simultaenously or only one occurring
What are the 3 Spasmogens
Histamine
Prostaglantin D2
Leukotrienes
How are spasmogens made
Arachidonic acid is present in cell membranes and is chopped out by phosphospholipase A2 (PLA2)
A. Acid is released which is the substrate for the lipooxygenase (LOX) pathway which produces leukotrienes or is the substrate for the cyclooxygenase (COX) pathway which produces prostaglandins
(Also platelets releasing platelet activating factor PAF)