Respiratory pathophysiology Flashcards
Are there sympathetic nerve endings in airway smooth muscle?
No, but beta -2 receptors are well represented.
What are the beta-2 receptors in the airway smooth muscle activated by?
catecholamines circulating in the systemic circulation
The beta -2 receptors in the airway smooth muscle is coupled to what proteins?
Gs protein
activation of the B2 receptors turns on the Gs protein, and this activates what?
adenylate cyclase
what does adenylate cyclase activate?
cAMP
What type of messenger is cAMP?
2nd messenger
along with protein kinase A, cAMP reduces what?
Ca+2 release from the sarcoplasmic reticulum
What does a reduction in Ca+2 from the SR ultimately cause?
reduction in muscle contraction and promotion of bronchodilation
when is the bronchodilation pathway by catecholamines turned off?
when phosphodiesterase 3 deactivates cAMP by converting it to AMP
What does NO do to smooth muscle?
it is a potent smooth muscle relaxant
Phospholipase C
Leukotrienes
Inositol triphosphate
These are all chemicals that do what to the airway?
increased airway resistance
Beta 2 agonists MOA?
B2 stimulation which increases cAMP and causes a decrease in Ca+2 (leading to bronchodilation)
name some Beta 2 agonists?
albuterol
salmeterol
metaproterenol
Anticholinergics MOA?
M3 antagonism leading to decreased IP3 which causes decreased Ca+2 (bronchodilation)
Name some anticholinergics?
atropine
glycopyrrolate
ipratropium
Corticosteroids (inhaled) MOA?
stimulates intracellular steroid receptors and regulates inflammatory protein synthesis which causes a decrease in airway inflammation and a decrease in airway hyper responsiveness
Cromolyn MOA?
Stabilizes mast cell membranes which decreases mediator release and provides prophylaxis for 1-2 hours
Leukotriene Modifiers MOA?
Inhibits 5 lipoxygenase enzyme which decreases leukotriene synthesis
Examples of Leukotriene modifiers?
zileuton
Montelukast
pranlukast
zafirlukast
Methylaxanthines MOA?
Inhibits phosphodiesterase leading to a decrease in cAMP
Releases endogenous catecholamines
Inhibits adenosine receptors
What volumes do pulmonary function tests measure?
static lung volumes
dynamic lung volumes
diffusing capacity
What is static lung volume?
how much the air the lungs can hold at a single point in time
what is dynamic lung volumes?
how quickly air can be moved in and out of the lungs over time
what is diffusing capacity?
How well the lungs can transfer gas across the alveolocapillary membrane
What are the static lung volumes?
How much air the lungs can hold at a single point in time
TLC FRC IRV ERV RV IC Vt VC
Which lung volumes provide an assessment of airway resistance and lung recoil?
dynamic lung volumes
What is FEV1?
Forced expiratory volume in 1 second.
volume of air that can be exhaled in one second.
What is the normal value for FEV1
> 80% predicted value
Which dynamic lung volumes are effort dependent?
FEV1
FVC
This dynamic volume takes age into account and it declines with age?
FEV1
What is forced vital capacity (FVC)?
Volume of air that can be exhaled after a deep inhalation
What is the normal value of FVC for male and female?
Male = 4.8 L Female = 3.7 L
What is the normal value of FEVI to FVC?
75 - 80%
Which dynamic volume measures airflow in the middle of expiration?
Forced expiratory flow at 25-75% vital capacity