Lung volumes (respiratory volumes) refers to the volume of gas in the lungs at a given time during the respiratory cycle. Lung capacities are obtained after summing up different lung volumes.Complete answer:
1) Tidal Volume (TV) is the normal volume of air that can be inhaled or exhaled during one respiratory cycle. It considers the functions of the respiratory centres, respiratory muscles, the mechanics of the lung and chest wall. Approximately it measures around 500 ml of air in a healthy adult man.
2) Inspiratory Reserve Volume (IRV) is the amount of air that can be forcibly inhaled after a normal respiratory cycle. IRV is reserve volume, so used during deep breathing. It values about 1900-3300ml.
3) Expiratory Reserve Volume (ERV) is the volume of air that can be exhaled forcibly. Its range value is 700-1200ml.
4) Residual Volume (RV) is the volume of air remaining in the lungs after forcible exhalation. Its value is about 1200ml.
1) Inspiratory capacity (IC) = IRV+TV
2) Total Lung Capacity (TLC) = TV+ IRV + ERV +RV
3) Vital Capacity (VC)= TV+IRV+ERV
4) Function Residual Capacity (FRC)= RV+ERV
|Tidal volume||Residual Volume|
|It is the total amount of air inhaled or exhaled during regular or relaxed breathing.||It is the volume of air left in the lungs post a forcible expiration.|
|Approximately it measures around 500 ml of air in a healthy adult man.||Approximately it measures around 1100-1200 ml of air in a healthy adult man.|
Measurement of lung volumes can be done using
> Spirometry Body
> Nitrogen washout
> Helium dilution Note:
Lung volumes and lung capacities consider the volume of air in the lungs during the respiratory cycle. The average total lung capacity of an adult human measures 6 litres. Tidal breathing is normal breathing so the tidal volume is the air that is inhaled or exhaled during that breathing. Air pollution exposure affects lung capacity and lung volume. Alveoli works as the main site where gaseous exchange inside lungs takes place. Apart from alveoli, the gaseous exchange also occurs between blood and tissues. The gaseous exchange of oxygen and carbon dioxide in alveoli and blood-tissues sites happens by diffusion. Factors that can affect the rate of diffusion are:
> Solubility of gases
> The thickness of the membranes involved in diffusion.
Partial pressure is an individual pressure contributed by an individual gas in a mixture of gases. It is denoted as pO$_2$ for oxygen and pCO$_2$ for carbon dioxide.