week 9 L2 mechanics of breathing 2 Flashcards
what are the things that contract in inspiration
diaphragm
external inter-costals
does forced inspiration work against or with elastic recoil
they work against elastic recoil
what are the physical factors effecting air flow
- airway resistance
- alveolar surface tension
- lung compliance and elastic recoil
how can airway resistence effect air flow
- friction on airway wall
- air pressure gradient
-mucous
bronchioles constriction - fluid
what causes alveolar surface tension
as alveolar are lined with water as they attract each other and not air can lead to collapse
how does surface tension effect airway flow
law of LaPlace
magnitude of inward-directed pressure is directly proportional to surface tension
what does surfactant do
- produce by type 2 alveolar cells
- proteins and lipids
breaks down hydrogen bonds between water molecules which stops alveolar collapsing
who is often effected in terms of not having surfactant
babies as they dont develop the surfactant (respiratory distress syndrome)
how does lung compliance and effect air flow
low compliaance = hard to stretch
high compliance = easy to stretch
factors that effect - high surface tension (reduced surfactant) and scar tissue on lungs
how does lung elastic recoil and effect air flow
-ability for lungs to rebound
factors that influence
- elastic fibres
- surfaces tension (if surface tension decreases so does elastic recoil)
what is tidal volume
normal inspiraed and expired volume about 500ml
what is inspiratory reserve volume
extra air inspired above normal inspired volume
what is expiratory reserve volume
extra air expired during forced expiration
what is inspiratory capacity
maximum volume of air that can be inspired TV+IRV
what is vital capacity
max amount of air expired after maximum inspiration TV + IRV + ERV
