respiratory physioex

obstructive problem

, expiratory flow is af- fected, FEV low

forced expiration

Although expiration is normally a passive process, ab- dominal wall muscles and the internal intercostal muscles can contract to force air from the lungs.

Residual volume (RV):

Amount of air remaining in the lungs after complete exhalation (1200 ml)

Forced vital capacity (FVC):

Amount of air that can be ex- pelled when the subject takes the deepest possible breath and exhales as completely and rapidly as possible

Expiratory reserve volume (ERV):

Amount of air that can be forcefully exhaled after a normal tidal volume exhalation (1200 ml)

Inspiratory reserve volume (IRV):

Amount of air that can be forcefully inhaled after a normal tidal volume inhalation (3100 ml)

expiration

During normal expiration, the inspiratory muscles relax, causing the diaphragm to rise and the chest wall to move inward. The thorax re- turns to its normal shape due to the elastic properties of the lung and thoracic wall. Like a deflating balloon, the pressure in the lungs rises, which forces air out of the lungs and airways.

Vital capacity (VC):

Maximum amount of air that can be ex- haled after a normal maximal inspiration (4800 ml) VC = TV + IRV + ERV

Forced expiratory volume (FEV1):

Measures the percent- age of the vital capacity that is exhaled during 1 second of the FVC test (normally 75% to 85% of the vital capacity)

tidal volume

Normal quiet breathing moves about 500 ml (0.5 liter) of air (the tidal vol- ume) in and out of the lungs with each breath, but this amount can vary due to a person's size, sex, age, physical condition, and immediate respiratory needs.

Total lung capacity (TLC):

Sum of vital capacity and residual volume

thoracic volume

These cooperative actions (inspiration and expiration) increase the thoracic volume. Because the increase in thoracic volume causes a partial vacuum, air rushes into the lungs.

surfactant

a detergent-like lipoprotein that decreases surface tension by reducing the attraction of water molecules for each other, the aqueous film covering the alveolar surfaces contains it

respiration

eathing are inspiration, during which air is taken into the lungs, and expiration, during which air is expelled from the lungs. Inspiration occurs as the external intercostal muscles and the diaphragm contract. The diaphragm, normally a dome-shaped muscle, flattens as it moves inferiorly while the external intercostal muscles between the ribs lift the rib cage.

restrictive problem

might indicate reduced inspiratory volume

surface tension

unequal attraction produces tension at the liquid surface, At any gas-liquid boundary, the molecules of the liquid are attracted more strongly to each other than they are to the air molecules, resists any force that tends to increase surface area, it acts to decrease the size of hollow spaces, such as the alveoli or mi- croscopic air spaces within the lungs.