Expiratory Reserve Volume ERV volume of air that can be forcefully expired following a resting expiration Inspiratory Reserve Volume IRV Volume of air that can be forcefully inspired following resting inspiration ID: 781967
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Slide1
Slide2Volumes
Tidal Volume (TV) = volume of air during one resting respiratory cycle.
Expiratory Reserve Volume (ERV) = volume of air that can be forcefully expired, following a resting expiration.
Inspiratory Reserve Volume (IRV) = Volume of air that can be forcefully inspired, following resting inspiration.
Residual Volume (RV) = Volume of air that remains in lungs. About 1200mL.
Slide3Capacities
Vital Capacity (VC) = maximal amount of air that can be expired after maximal inspiration.
VC = TV + IRV + ERV
Functional Residual Capacity (FRC) = Amount of air that remains in lungs following a relaxed expiration.
FRC = ERV + RV
Total Lung Capacity (TLC) = Maximal volume of air in lungs.
TLC = RV + ERV + TV + IRV or TLC = VC + RV
Slide4Inspiration.
Relaxed inspiration. Diaphragm and external intercostal muscles contract.
Forceful inspiration. Diaphragm and external intercostal are supplemented by the sternocleidomastoid and pectoralis minor muscles.
Slide5Expiration.
Normal expiration is due to elastic recoil of lungs and abdominal organs.
Forceful expiration is supplemented by the internal intercostal muscles and abdominal wall muscles.
Slide6Factors Affecting Breathing
Medullary Respiratory Center – detects changes in CO
2
and H
+
(pH) concentrations
Major Stimulus for breathing
Carotid Bodies & Aortic Bodies – detects changes in O
2
concentrations
CO
2
+ H
2
O
H
2
CO
3
HCO
3
-
+
H
+
Slide7Hering
-Breuer Reflex:
Stretch receptors in lung tissues are stimulated during inspiration.
Sensory impulses travel via the vagus nerve to the
pneumotaxic
center of the respiratory center in the pons.
Duration of inspiration shortens. Prevents
overinflation
.
CO
2
+ H
2
O
H
2CO3 HCO3-
+ H+