Lecture 3: Airway Resistance & Pulmonary Compliance Flashcards
airway resistance is normally very ___
small
changes in airways resistance are brought about by changes in ___ of the airways by ____ of smooth muscles of the airways
radius; contraction
airway radius may change due to ___, ___ or ___ factors
physical, neural, chemical
resistance is the opposition to ____
motion
the flow of air into the lungs is ___ proportional to resistance for laminar flow
inversely
in astma, airway smooth muscle constricts and causes __- and ____
higher airway resistance and more work to breathe
airway resistance is primarily determined by the ___ of the airways
radius
air flow is ___ proportional to pressure difference between atmosphere and alveoli
directly
what is the major site of airway resistance in the airways?
large. bronchi
in the conducting zone, airflow velocity ___- substantially as the effective cross-sectional area increase
decrease
in the respiratory zone, airway generations exist in ___ rather than in series
parallel
what are the 4 factors that contribute to airway resistance
- lung volume
- viscosity
- autonomic nervous sytem
- other agents
what is the effect of increasing lung volume on air resistance?
increases airways diameter, so decreases resistance
the relationship between the reciprocal of resistance (conductance) and volume is ___
linear
what is the effect of increased air viscosity on airway resistance>
increases pressure and resistance
breathing ___ viscosity air, such as a mix of O2 with __-, decreases resistance and can be used as treatment for ___
low; He; status asthmaticus
what is the effect of parasympathetic activation on airway resistance?
constriction of airways and more resistance
what is the effect of sympathetic activation on airway resistance?
relaxation of B2 receptors, decreases resistance
B2 agonists are useful in treatment of ____ (ex of drug: ___)
asthma; albuterol
histamine, Ach, TxA2, leukotrienes etc are released in response to triggers (allergies, viral infections etc) and cause what effect on airway resistance?
bronchoconstriction; increased resistance
____ is characterized by increased responsiveness of the airways to various stimuli
asthma
astma manifests as widespread ___ of the airways
narrowing
what are 4 symptoms of asthma?
- excess mucus secretion
- chronic inflammation
- chest tightening
- coughing / wheezing
asthma affects ~____ people worldwide and causes ____ deaths annually
300 million; 250 thousand
lung compliance refers to __
how easy it is for the lung to expand
the ____ the compliance, the easier it is for the lungs to expand at any given change in Ptp
greater
in ___ there is destruction of the lung tissue so lungs are unable to spring back after inspiration. In this case, the compliance is too ____
emphysema; great
the ___ the compliance, there is a lesser increase in lung volume for any given increase in Ptp
lower
in ____, the deposition of collagen fibres into the lungs results in thickened, scar-tissue around the alveoli, making it harder to expand the lungs. In this case, the compliance is too ___
fibrosis; low
emphysema is also called ___
floppy lungs
fibrosis is also called ___
stiff lungs
compliance is the inverse of ____ (the ability to regain original shape after distension or compression)
elactance
emphysema is classed as a ____ disease
obstructive
why is emphysema classed as an obstructive disease?
because the conducting airways will collapse due to loss of surrounding support tissue
pulmonary fibrosis is classed as a ____ disease
restrictive
why is pulmonary fibrosis classed as a restrictive disease?
because there is a restriction to the normal movement of air into the lungs
lung volume depends on what 2 things?
- transpulmonary pressure
2. compliance of lung tissue
what are the 2 major determinants of compliance?
- stretchability of lung tissue
2. surface tension at the air-liquid interface in alveoli
the surface tension at the air-liquid interface of the alveoli is decreased by ___
surfactant
____ is deficient in respiratory distress syndrome of the newborn
surfactant
lungs inflated with ___ have much higher compliance compared to air-filled lungs
saline
difference between air and liquid filled lungs is due to ____
surface tension forces
why does a lung full of saline have higher compliance than air-filled lung?
saline abolishes the surface tension forces without affecting tissue forces q
compliance is measured on the ____ limb
expiration
what would happen if there were pressure differences between alveoli?
air would move to low pressure system and alveolus with the larger pressure would collapse
in smaller alveoli, molecules of surfactant are ___ in relation to each other, which decreases_____ more than in larger alveoli
closer; surface tension forces
what is responsible for stabilizing pressure in the alveoli?
surfactant
what is surfactant made of ?
mix of proteins and phospholipids
what cells secrete surfactant?
type 2 alveolar cells
surfactant ___ lung compliance
increases
secretion of surfactant is increased by ____
taking a large breath that will stretch type 2 alveolar cells
type 2 alveolar cells are not made until the ___ week pf pregnancy
24
babies with RDSN have to work harder to breathe due to ___ compliance
decreased
if a mother is going into premature labour (24 weeks or before), what can be given to them to increase their babies alveolar 2 activity?
corticosteroids
wha can be given to a baby after birth to better their breathing?
exogenous surfactant
