Lec 4 Flashcards
Explain quiet breathing (Eupnea)
-is passive expiration (elastic recoil)
-2 types
-diaphragmatic breathing (deep)
diaphragm contraction generates neg. pulmonary pressure
- costal breathing (shallow)
external intercostal muscles generate neg. pulmonary pressure
explain forced breathing (hyperpnoea), and the difference between hyperventilation
-is active expiration
hyperpnoea- increases breathing- via rate and/or depth.
hyperventilation- increase in ventilation above that predicted by metabolic rate (over breathing)
- increased breathing during running is a hyperpnoea but not a hyperventilation (breathing has increase to match increased metabolic rate during exercise)
define Vt, f, and ‘Ve
Vt= tidal volume, volume of inhaled or exhaled in one breathe (500ml)
f= respiratory rate, number of breaths per minute
‘Ve= minute ventilation rate, amount of air moved each minute
what is dead space
-any part of tidal volume that is not involved in gas exchanged
-is made up of anatomical (air in conducting zone) and alveolar (air that reaches alveoli with poor blood flow) dead space (physiological dead space = anatomical + alveolar)
- not all tidal volume participates in gas exchange
define Vd, ‘Va
Vd= dead space, amount of air in conducting zone
‘Va= alveolar ventilation, amount of air reaching the alveoli each minute
respiratory volume table
*refer to onenote
define ERV, IRV, and RV
-ERV = expiratory reserve volume, amount of additional air that you can force out of your lung after you have expired normally (1000ml)
-IRV = inspiratory reserve volume, amount of additional air that you can inhaled after you have inhaled normally (1900-3300ml)
- RV= residual volume, amount of air left in the lungs after a maximum expiration (1100ml)
define IC, FRC, VC, and TL
IC= inspiratory capacity, amount of air you can take into the lungs after normal expiration is completed = Vt + IRV
FRC= functional residual capacity, amount of air remaining in the lungs after you have expired normally = ERV + RV
VC= vital capacity, max amount of air you can move into or out of lungs= ERV + Vt + IRV
TL= total lung capacity, total volume in lungs = VC + RV
energetic tradeoff for breathing patterns
- for the same ‘Ve
-either increased Vt + decreased f, and Va increase (but increased energetic cost)
or
-increased f + decreased Vt patterns
-decreased energtic cost (but Vd increases and ‘Va decreases)
VENTILATION IS A BALANCE BETWEEN ‘Va + COST
how hard it is to ventilate the lungs depends on
-alveolar fluid surface tension
-lung compliance (Cl)
-airway resistance (R)
explain alveolar fluid surface tension
-thin layer of fluid lines alveoli
- surface tension created at air-water interface (water molecules are more strongly attracted to themselves vs molecuules in air)
-pulls alveoli inwards to their smallest diameter (want smaller surface tension)
- about 2/3 of lung elastic recoil due to surface tension
-pulmonary surfactant, secreted by type 2 cells, decreases surface tension in alveoli
define LC
Cl= lung compliance, how much pressure is required to stretch the lungs + chest wall to a certain volume
-it is related to lung elasticity + surface tension
-decreases due to lung scarring, excess fluid in lungs, lack of surfactants, weak respiratory muscles, and stiff chest wall
At rest, what percentage of the total energy demand does ventilation take
3-5% of total energy demand
Define FVC, FEV1, and FEV1/FVC * 100
FVC= forced vital capacity, max volume expired after max inspiration
FEV1= forced expired volume in 1 sec
Fev1/FVC*100= also called FER
What are normal values for spirometry tests
-for a healthy pop., 95% of individuals wil have values within +/-2 SD from the mean
-above/below this rand is the upper + lower limit
-if patient value is lower then the LLN (lower limit of normal), a respiratory condition is likely
