Respiratory Volumes and Capacities

What factors can effect respiratory volumes and capacities?

age, sex, size, physical condition

What are the different types of lung volume?

tidal volume

inspiratory reserve volume

expiratory reserve volume

residual volume/reserve volume

what is tidal volume?

the volume that enters and leaves with each breath

from normal, quiet inspiration to normal quiet expiration

what is the average tidal volume?

0.5L

What factors can effect tidal volume?

increased in pregnancy

What is inspiratory reserve volume?

extra volume that can be inspired above the tidal volume

from normal quiet inspiration to maximum inspiration

what is the average inspiratory reserve volume?

2.5L

What can effect inspiratory reserve volume?

muscle strength, lung compliance, the volume at the end of tidal volume

what is the expiratory reserve volume?

extra volume that can be expired below tidal volume

from normal quiet expiration to maximum expiration

what is the average expiratory reserve volume?

1.5L

what can effect expiratory reserve volume?

muscle strength, airway resistance

reduced in pregnancy, obesity, trachea/bronchi obstruction

what is residual volume?

volume remaining after maximum expiration

what is the average residual volume?

1.5L

what are the lung capacities?

vital capacity

inspiratory capacity

functional residual capacity

total lung capacity

How do lung capacities differ from volumes?

capacities are fixed as they cannot change with the pattern of breathing unlike lung volumes

capacities are composed of 2 or more lung volumes

What is vital capacity?

the volume that can be exhaled after maximum inspiration

i.e. maximum inspiration to maximum expiration

inspiratory reserve volume + tidal volume + expiratory reserve volume

What is the average vital capacity?

4.5 L

What can effect vital capacity?

disease

requires adequate lung compliance, muscle strength, and low airway resistance

What is inspiratory capacity?

the volume breathed in from quiet expiration to maximum inspiration

tidal volume + inspiratory reserve volume

What is the average inspiratory capacity?

3 L

What is functional residual capacity?

the volume remaining after quiet expiration

expiratory reserve volume + residual volume

What is the average functional residual capacity?

3 L

What can effect functional residual capacity?

height, gender, posture, changes in lung compliance

What is total lung capacity?

the volume of air in the lungs after maximum inspiration

the sum of all volumes

What is the average total lung capacity?

6 L

How do you measure respiratory capacities?

A spirometer

How does a spirometer work?

as the person breathes the volume of air exhaled can be read on an indicator that shows the changes in air volume inside the apparatus

what is dead space volume?

air that remains in the conducting zone passageways and never reaches the alveoli so does not participate in gas exchange

What is the average dead space volume?

150ml