L9.2 Respiratory System II Flashcards
what are physical factors influencing ventilation?
- airway resistance
- alveolar surface tension
- lung compliance and elastic recoil
what does the airflow rate depend on?
- air pressure gradient (difference between atmospheric and intra-alveolar pressure)
- airway resistance
airway resistance is _____ in healthy individuals
airway resistance is VERY LOW in healthy individuals
increased airway resistance =?
increased airway resistance = slower airflow
main factor increasing airway resistance is …
main factor increasing airway resistance is REDUCED BRONCHIOLE RADIUS
alveoli are lined with a layer of water which creates _____
this can cause alveoli to ____ (___)
resists ____ of alveoli (___)
alveoli are lined with a layer of water which creates SURFACE TENSION
this can cause alveoli to COLLAPSE (EXPIRATION)
resists INFLATION of alveoli (INSPIRATION)
what is the law of LaPlace
P = 2T/R
- the magnitude of inward-direction pressure (P) is directly proportional to the surface tension (T) and inversely proportional to the radius (R) of the alveolus
the collapsibility of an alveolus can be reduced by ______ the surface tension
the collapsibility of an alveolus can be reduced by DECREASING the surface tension
what is surfactant? and its purposes?
surfactant breaks the surface tension of water (produced by type II alveolar cells; mixture of protein and lipids)
breaks hydrogen bonds between water molecules (stops alveoli from collapsing; easier to expand alveoli during inspiration)
what is lung compliance?
high compliance = ?
low compliance = ?
stretchability of the lungs during inspiration
high compliance = easily stretched
low compliance = hard to stretch
what are factors reducing compliance?
- high surface tension (reduced surfactant)
- scarring of lung tissue
what is elastic recoil?
- ability of lungs to rebound (shrink)
- important during expiration
elastic recoil is influenced by two factors: ? and ?
- elastic fibres
- surface tension (decrease surface tension = decrease elastic recoil)
define tidal volume
air inspired or expired during quiet breathing
define inspiratory reserve volume
extra air inspired during forced inpsiration
define expiratory reserve volume
extra air expired during forced expiration
define residual volume
air left in the lungs after forced expiration
define inspiratory capacity
maximum volume of air that can be inspired
TV + IRV
define vital capacity
maximum amount of air expired after maximum inspiration
TV + IRV + ERV
define functional residual capacity
volume of air in lungs after normal expiration
ERV + RV
define total lung capacity
maximum volume of air that the lungs can hold
VC + RV
what is pulmonary ventilation
volume of air breathed in and out per minute
pulmonary ventilation = tidal volume X respiratory rate
would it be better for an athlete to increase the tidal volume or the respiratory rate?
take bigger breaths (tidal volume) because dead space is lost with every breath, it is more efficient to increase ventilation by increasing tidal volume
what is anatomical dead space?
the volume of air available for gas exchange is less than the tidal volume BC some of the tidal volume never makes it into the alveoli
anatomical dead space = air stuck in the airways
what is alveolar ventilation?
volume of air exchanged between the atmosphere and alveoli = air available for gas exchange; takes dead space into account
alveolar ventilation = (tidal volume - dead space) X respiratory rate
