Innervation of the Airways and Obstructive and Restrictive Disease Flashcards
what does the parasympathetic nervous system provide innervation to?
all of tracheobronchial tree
what does the parasympathetic nervous system specifically innervate in the lungs?
airway smooth muscle
submucosal glands
what does the sympathetic nervous system innervate in the lungs?
larger airways, not smaller airways
B2 receptors respond to circulating epinephrine
what does the eNANC (nonadrenergic noncholinergic) system lead to?
smooth muscle contraction
increased mucous
vasodilation, microvascular leakage, inflammatory cell activity
what does the iNANC (nonadrenergic noncholinergic) system lead to?
smooth muscle relaxation
decreased smooth muscle proliferation
decreased platelet aggregation and adhesion
what do eNANC nerves innervate?
airway smooth muscle
submucosal glands
blood vessels
form diffuse network immediately below the epithelium
what are the major neurotransmitters of the eNANC system?
tachykinins, including neurokinin and substance P
what fibers contain the major neurotransmitters of the eNANC system?
C fiber afferents mainly
what is the iNANC system probably critical for?
proper function of the lower airways
what are the major neurotransmitters of the iNANC system?
nitric oxide
VIP also involved
why is nitric oxide an ideal local transcellular messenger?
small
lipophilic
very short duration of action
what does nitric oxide do?
antagonizes actions of acetylcholine: smooth muscle relaxation, decreases airway smooth muscle proliferation, and decreases platelet aggregation and adhesion
what are some inflammatory mediators?
histamine
serotonin
prostaglandins
leukotrienes
platelet activating factor
reactive oxygen species
cytokines
what does histamine on the H1 receptor cause?
smooth muscle contraction, microvascular leakage and edema
what does histamine on the H2 receptor cause?
bronchodilation, negative feedback of histamine release
minor
what does serotonin cause?
mast cell degranulation
vasoconstriction
bronchoconstriction
microvascular leakage
what do prostaglandins mediate?
bronchoconstriction
airway hyperreactivity
bronchodilation
chemoattraction
what do leukotrienes cause?
slow reactive substance (anaphylaxis)
contraction
increased microvascular permeability
mucous production
eosinophil and neutrophil chemoattraction
what is platelet activating factor formed secondarily to?
membrane phospholipase A2 activation
what does platelet activating factor do?
airway constriction
microvascular leakage
eosinophil, platelet chemotactant
sustained bronchial hyper-responsiveness
what do reactive oxygen species do?
destruction of microorganisms and neoplastic cells
inflammatory mediator release
what happens in restrictive disease?
lungs cannot expand fully because of disease of the lung itself, the pleura, or the chest wall
compliance reduced
what are common causes of restrictive disease?
pleuropneumonia
pneumonia
pulmonary edema
obesity
what happens in obstructive disease?
lungs cannot fully empty
what are common causes of obstructive disease?
canine bronchitis
feline asthma
equine inflammatory lung disease
equine recurrent airway obstruction
in restrictive diseases, ______________, which is the inverse of ______________, is increased
elastance
compliance
what affects the neuromuscular system that can cause restrictive disease?
myasthenia gravis
botulism
do animals with restrictive diseases have a hard time breathing in or breathing out?
in
why do patients with restrictive disease tend to breathe rapidly and shallowly?
elastic work is increased, will be even more increased if breathe deeper
non-elastic work component is higher when breathing faster
what characterizes an obstructive lung disease?
increase in resistance
what affects airway resistance?
parasympathetic stimulation
sympathetic stimulation
nonadrenergic noncholinergic
obstruction
compression of airways
what does loss of tethering result in?
airway obstruction: not held open
what are some common histopathologic features of chronic bronchitic diseases?
goblet cell hypertrophy and hyperplasia
mononuclear cell infiltration
increased connective tissue within the lamina propria
epithelial hyperplasia
what causes asthma-type diseases?
allergen-mediated mechanisms
what are some common histopathologic features of airway hyperreactivity?
increased mucus production
mucosal edema
thickening of the epithelial basement membrane
infiltration of the airway walls by inflammatory cells
do eosinophils predominate in equine inflammatory airway disease?
very rarely
what is the predominant cell type in recurrent airway obstruction?
neutrophils
postganglionic parasympathetics: ganglionic transmission is mediated via _____________________, whereas actual smooth muscle contraction is mediated via _____________________
acetylcholine through nicotinic receptors
acetylcholine via muscarinic receptors
how does an M3 receptor in airway smooth muscle lead to contraction?
phospholipase C activated, which forms IP3, which causes release of calcium ions
what do M2 receptors mediate?
inhibit release of acetylcholine
downregulate its own response
norepinephrine is the principle neurotransmitter for ____________, whereas epinephrine is for the ________________
nerves
adrenal medulla
what does activation of B2 receptors in the sympathetic nervous system lead to?
improved mucus clearance
adenylate cyclase leads to accumulation of intracellular cAMP: decreased levels of calcium through protein kinase A
when are eNANC nerves particularly important?
viral-induced airway hyperresponsiveness
injured respiratory epithelium exposes nerves
what is serotonin thought to be important in?
feline asthma
what prostaglandins mediate bronchoconstriction?
PGD2
PGF2alpha
TXA2
what prostaglandins mediate airway hyperreactivity?
TXA
TGD
what prostaglandin mediates bronchodilation?
PGE2
in obstructive disease, the animal must generate a __________________ for a given amount of _______
higher driving pressure
flow
what is resistance like in restrictive diseases?
normal or lower than normal
hard to take in, but easy to get rid of
why do patients with restrictive disease tend to breathe rapidly and shallowly?
with increases breathing rates, the non-elastic work component is higher
with deeper breaths, the elastic work is greater
they already have a higher elastic work due to the disease
what does beta-2 sympathetic activation lead to?
bronchodilation
circulating beta-2 stimulation is what causes it (not innervation)
why is airway resistance lower at high lung volumes?
airways are tethered open to greater extent
is there usually a primary infectious component to chronic bronchitis?
no
