CVR 24 work of breathing Flashcards
(25 cards)
What is compliance
How great a change in lung volume occurs due to a change in transmural pressure.
Fatter hysterisis loop implies?
more work like pulmonary fibrosis or COPD
Elastic forces represent what percent of work
70%
What is teh optimum tidal volume
500ml
What two components make up elastic work
tissue eastic forces fibres
surface tensin (laplaces law)
What property reduces alveolar size?
water to water surface tension
What is a surfactant
synthesis and storage via type 2 alveolar cells at 22-32 weeks
aid in immune function
SPA SPB SPC
SPD
What is laplaces law
Laplace’s Law: Relates pressure to (surface) tension and radius
small radius = High Pressure
Alveli would collapse into bigger ones without
Surfactant molecules position at air-liquid interface with ____________chains projecting into alveolar air and_________ end into the fluid lining of the alveolus.
hydrophobic fatty acid chains
Hydrophyllic end
Where is surface tension lowering effect greatest
as tehy become smaller in expiration
___________ Previously known as _________ disease
Developing foetal lungs do not normally ______________until late in pregnacy.
Therefore, premature infants may not have enough pulmonary __________ and struggle to breathe.
Respiratory distress syndrome of newborns
hylaine membrane disease
synthesise pulmonary surfactant
surfactant
Tx of RDS
corticosteroids to mother
oxygen
survanta
When an alveolus in a group of interconnected alveoli begin to collapse, the surrounding alveoli ________
Are stretched
Alveoli interdependence
Primary purpose of non elastic work
resistance to airflow
Normal pressure difference between mouth and alveoli is approximately ___________
0.98 mmHg
\_\_\_\_\_\_\_\_\_\_\_\_ Relates \_\_\_\_\_\_\_\_\_ (volume transported per time unit) to airway radius and to distance the air is transported
Hagen-Poiseuille Law
flow rate to radius
If airway radius reduced to 50%, resistance increases _____
16-fold!
Resistance to air flow decreases with ______ lung volume (______) airway expanded
increasing
Inspiration
________ is a streamline flow (smooth)
laminar flow
What number determines if flow is turbulent or laminar
reynold number
<2000 = laminar
>4000 = turbulent
What is the wall made of in the bronchioles and the lumen
smooth muscle in walls
mucus in lumen increased in infaction
Circulating epinephrine (adrenaline)
causes __________
bronchiolar smooth muscle relaxation
Bronchoconstriction (decrease in radius of bronchioles)
via ____________
Contraction of bronchiolar smooth muscles
bronchodiation
acetycholine
Histamine and C02 increases do what to smooth muscle tone
bronchoconstriction
Which Resp disease incraeses flow resistive work, has no effect on elastic work and decreases FEV but not FVC
COPA asthma
