Lung volumes refer to the amount of air that is inhaled or exhaled or left in the lungs after forced respiration. Respiration takes place only in the alveoli and the alveolar duct. So, there is no gaseous exchange in the respiratory tract such as the mouth and trachea. This respiratory passage is the anatomical dead space (about 150 ml). Here we will be discussing the concept of different terms used in the respiration process (lung volumes and capacities), along with their normal values.
Besides that, we will also discuss the tests to check your lung capacity and exercises you need to do, for better lung strength.
Let’s look at some of the terms used for lung volumes.
- Tidal Volume (TV):- Tidal volume is the total amount of air that passes in and out of the lungs during each breathing cycle. The normal value for an adult is about 500 ml at rest.
- Inspiratory Residual Volume (IRV):- Inspiratory residual volume is the extra volume of air that can be inhaled during maximal inspiration. In others words, it is an extra volume of air inhaled above the tidal volume. The normal value is about 3000 ml for males and 2100 ml for females.
- Expiratory Residual Volume (ERV):- Expiratory residual volume is the extra volume of air that can be exhaled during maximal expiration. In other words, it is an extra volume of air exhaled above the tidal volume. The normal value is about 1200 ml for males and 700 ml for females.
- Residual Volume (RV):- Residual volume is the amount of air that remains in the lungs after maximal expiration. In other words, it is the amount of air present in the lungs, that can not be expelled. The normal residual volume is about 1200 ml in adults.
(Note:- If the lungs are empty, then the tissues of the lungs will adhere to each other. So, the lungs will collapse. Thus, it helps to prevent the lungs from collapsing. Besides, the direct measurement of residual volume is not possible.)
- Alveolar dead space refers to the alveolar duct where gaseous exchange does not take place. Alveolar dead space is negligible in healthy people.
Besides the lung volumes, the term lung capacity is also widely used. Some of the terms related to lung capacities are stated below.
- Inspiratory Capacity (IC):- It is the sum of tidal volume and inspiratory reserve volume. In other words, the total volume of air that can be inspired during maximal inspiration is the inspiratory capacity. Mathematically, IC= TV + IRV. Putting the values of TV and IRV, we obtain that the normal IC value for males is about 3500 ml. Also for females, it is about 2600 ml.
- Functional Residual Capacity (FRC):- It is the sum of expiratory residual volume and the residual volume. In other words, the total amount of air that remains in the lungs after a quiet expiration is the functional residual capacity. The value of FRC for a normal person is about 2500 ml.
- Vital Capacity (VC):- Vital capacity is the maximum volume of air that passes in and out of the lungs during force breathing.
VC= TV + IRV + ERV
Putting the values from the above paragraphs we get that the normal vital capacity of adult males is about 4700 ml. Similarly for adult females, it is about 3400 ml.
- Total Lung Capacity (TLC):- Maximum amount of air, lungs can hold in a single breathing cycle is the total lung capacity.
TLC = VC + RV
= (ERV + IC) + RV
= ERV + TV + IRV + RV
So, this is the total lung capacity formula. By using the given formula, we can say that the normal total lung capacity for men is about 5900 ml. Similarly, for women, it is about 4600 ml.
Factors affecting the lung capacity
The lung capacity of a person depends upon factors such as age, sex, size, etc. Hence, knowing the exact lung capacity for any person is not possible. However, a certain relationship can be developed between lung capacity and any of the stated factors.
You may make use of the lung capacity calculator to measure your lungs’ capacities. However, it will not be able to give you an exact result.
Different researchers have come up with the following conclusions regarding lung capacity.
Up to the age of 25, the lung volumes and capacities keep on increasing, After that it is stable up to a certain age period. After the age of 35, the value begins to decrease.
The difference between forced vital capacity (FVC) of males and females is not significant in their childhood. However, in early and late adulthood, the value is higher in the male in comparison to that of the female.
With an increase in age, the value keeps on increasing. This is possible due to the weakening of the muscles of the diaphragm, and the respiratory tract. Low immunity can lead to numerous kinds of respiratory tract infections. Hence, the value keeps on decreasing.
Lung capacity exercises in the house
By using different kinds of breathing exercises, you can increase the lung’s strength. This in turn will improve lung capacity. The video shown below is an example of a breathing exercise that you can follow to improve your lung capacity.
This is a reference video. You may even consult the doctor to know more about the breathing exercises.
Lung Function test
In the hospital, the doctor will make use of the machine known as the spirometer to check your lung volume and capacities. After doing the diagnosis, they will recommend you with the drugs, exercises, diet plan, etc. You need to follow the instructions give to you, by your doctor.