vital capacity experiment

research question:

how much is the vital capacity of a healthy person compared to a person with tuberculosis?

 Hypothesis:

the vital capacity of a healthy person should be equal the body surface area multiplied by 2000 in the case of a female and in a male's case it is the body surface area multiplied by 2500.

 Work plan:

1. The first thing is to calculate the body surface area of each person taking part in the experiment
2. Calculate the expected viral capacity of each participating person
3. Calculate the actual vital capacity, which is done using a balloon. The participating people should take a deep breath and exhale in the balloon till its not possible anymore. This could be done multiple times and then take the biggest balloon.
4. Measure the balloon diameter and calculate the volume
5. Lastly you calculate the vital capacity percentage, which is done by the expected and actual vital capacity.

The only thing that is needed for this experiment is a balloon for each person participating. Before starting the balloon should be stretched a bit so it will be easier to fill with air.

 Results:

For females you can calculate the expected viral capacity by multiplying the body surface area by 2000. And the formula to calculate the body surface area is: The root of  (the height times the weight of the person divided by 3600)                                                                                                                                              The graph that shows the relation between a balloon diameter and the lung capacity is shown in the graph.

The actual lung capacities are:                            

1st participant:  3.00 cm3

2nd participant: 3.60 cm3

3rd participant : 2.25 cm3

4th participant : 1.75 cm3

1st participant: age:46 years, weight: 65 kg, length :166 cm, female, balloon:17.5cm diameter, body surface area: 1.731 M2, expected capacity: 3.462 cm3                                                                                                                                                                                                                                                                                 2nd participant: age:18 year, Length:171 cm, Weight: 67 kg, female, balloon: 19 cm diameter, body surface area: 1.784 M2 , expected capacity: 3.568 cm3                                                                                                                                                                                                                                                                                  3rd participant: age: 15 years, Length: 166 cm, weight: 48 kg, female, balloon 16 cm diameter. Body surface are: 1.487 m2, expected capacity: 2.974 cm3                                                                                                                                                                                                                                                                                        4th participant;  age:12 years, length:168 cm, weight 48 kg, female, balloon: 15cm diameter.  Body surface are: 1.497 M2, expected capacity: 2.994 cm3

The last step is to calculate the vital capacity percentage:

1st participant, 86.7%

2nd participant, 100.9 %

3rd participant, 75.7 %

4th participant, 58,5%

Tuberculosis patients have about 20% to 50% of the expected lung capacity, this has to do with how severe it is weather it will be around 20% or 50%

 Conclusion:

To conclude, the vital capacity of a tuberculosis is generally speaking lower than a healthy person. The amount of difference differs from patient to patient  but it differs at least around 10% of the person’s lung capacity. A healthy person with a good fitness should be able to use 80/90%  of his vital capacity while a tuberculosis can only reach 50% in the best case and mostly they reach less than that.

 Discussion:

The general thing that affect a person's vital capacity are:

• Age, a person below 25 should have the highest viral capacity
• Gender, generally speaking a male has a higher viral capacity than a female
• Size of the chest cage, if you have a bigger chest cage you will have a better viral capacity
• Fitness, your physical fitness can increase your viral capacity
• Posture
• Also race has been proven to effect a person's vital capacity

 There are several discussion points in our experiment. This is because the participating persons were from the same age and race which might have effected the results, as these are both factors that can effect the results.

This experiment was done and written by: Loebna Sabbah