Respiratory System Mechanics
Expiratory reserve volume(ERV)
amount of air that can be forcefully expired after a normal tidal volume expiration (male 1200 ml;female, 700 ml)
Inspiratory reserve volume (IRV)
amount of air that can be forcefully inspired after a normal tidal volume inspiration (male;female, 1900 ml)
What causes the negative pressure condition?
- the tendency of the lung to recoil because of its elastic properties, the surface tension of the alveolar fluid - the tendency of compressed chest wall to recoil and expand outward, two forces pull the lungs away from the thoratic wall, creats a partial vacume in pleural cavity
How do you find the total lung capacity?
TV + IRV + ERV +RV=TLC
How do you find the vital capacity?
TV + IRV + ERV=VC
surfacant
a detergent-like mixture of lipids and proteins that decreases surface tension, reduces the attraction of water molecules to each other
diaphragm
a dome shaped muscle, flattens as it moves inferiority while the external intercostal muscles lifts the ribs
expiration
air is expelled from the lungs
inspiration
air is taken into the lungs
Residual Volume(RV)
amount of air remaining in the lungs after forceful and complete expiration
residual volume (RV)
amount of air remaining in the lungs after forceful and complete expiration (male, 1200 ml; female,1100 ml)
Forced vital capacity (FVC)
amount of air that can be expelled when the subject takes the deepest possible inspiration and forcefully expires as completely and rapidly as possible
external intercostal muscles
between the ribs, lifts the rib cage as the diaphragm flattens
ventilation
breathing, the movement of air into and out of the lungs
Surfactant
detergent-like mixture of lipids and proteins that decreases surface tension by reducing the attraction of water molecules to each other
Minute Respiratory Volume (MRV)
is the volume of gas inhaled or exhaled from a person's lungs per minute
Total lung capacity (TLC)
maximum amount of air contained in lungs after a maximum inspiratory effort: TLC= TV+IRV+ERV+RV (male, 6000 ml; female, 4200 ml)
Total Lung Capacity
maximum amount of air contained in the lungs after a maximum inspiratory effort
Vital Capacity
maximum amount of air that can be inspired and then expired with maximal effort
Vital Capacity (VC)
maximum amount of air that can be inspired then expired with maximal effort: VC=TV+IRV+ERV (male, 4800 ml; female, 3100 ml)
Forced expiratory volume (FEV1)
measures the amount of the vital capacity that is expired during the first second of the FVC test (normally 75%-85% of the vital capacity)
Pneumothorax
opening created in the pleural membranes equalizes the intrapleural pressure with atmospheric pressure by allowing air to enter the pleural cavity, collapsed lung
interplural pressure
pressure in the pleural cavity
Tidal volume
the amount of air inspired and then expired with each breath under resting condidtions (500mL)
surface tension
unequal attraction produces tension at the liquid surface
