Lesson 5- Lung capacity

Peak flow meter

Measures peak expiratory flow (PEF), a person’s maximum speed of expiration

Vitalograph

Produces graph of the amount of air breathed out and how quickly. FEV₁ = Forced expiratory volume in one second ( How much air is forced out in one second)

Spirometer

Can give readings of TV, VC, Breathing rate and oxygen uptake and produces a graph

Spirometer trace diagram

Tidal volume (TV)

The amount of air that can be inhaled and exhaled during one normal breathing cycle.

Ventilation rate x breathing rate

Inspiratory reserve volume (IRV)

The amount of air that can be forcibly inhaled beyond a tidal inhalation. 3dm³ for men and 2dm³ for women.

Expiratory reserve volume (ERV)

The amount of air that can be forcibly exhaled beyond a tidal inhalation. 1.2dm³ for men and 0.2dm³ for women.

Residual volume

The amount of air remaining in the lungs after an ERV. 1.2dm³ for both men and women. Prevents lungs from collapsing and maintains a constant supply of oxygen for gas exchange.

Inspiratory capacity

Maximum volume of air a person can inhale after a normal exhalation. 

IRV + TV

Functional reserve capacity

Volume of air remaining in lungs after a passive exhalation.

ERV + RV

Vital capacity

The volume of air that can be exhaled when the deepest possible intake is followed by the strongest possible exhalation

TV + IRV + ERV

Total lung capacity

Total volume the lungs can hold

RV + VC

Breathing rate

Number of breaths per minute

Ventilation rate

Breathing rate x Tidal volume

Factors affecting lung capacity

-Age

-Sex

-Size

-Fitness

-Smoking or respiratory disease (reduces VC)

Actual spirometer trace

-Looks like this due to volume of gas (oxygen) in chamber decreasing over time

-Air breathed out mixture of oxygen and carbon dioxide

-Carbon dioxide absorbed by soda lime- only oxygen in chamber which is inhaled