# Anatomy and Physiology Lab Report

```Stephanie Lambrix
R 4:00 p.m.
The Effect of Height on Vital Capacity in Females
Introduction
Vital capacity is the “amount of air that is exhaled following maximal forced
inspiration” (Burns, and Smith 394). In other words, it is the greatest volume of air that
can be forcibly exhales after the deepest inspiration. Air pressure occurs when the lung
volume increases and decreases. Volume and pressure are inversely related. Boyle’s Law
focuses on this inverse relationship and states that when the volume of gas increases, the
pressure of gas decreases. Therefore, when the thoracic cavity increases, the pressure
decreases.
We investigated the relationship between vital capacity of taller women to the vital capacity
of shorter women. We hypothesized that a woman’s height will have an effect on vital
capacity. We predicted taller females will have higher vital capacity than shorter females.
The objective of this experiment was to determine the difference in vital capacity between
tall and short females.
Materials and Methods
Six tall females, 5’6” to 5’7”, and six short females, 5’ to 5’3”, measured their respiratory
volume with an instrument called a spirometer. To begin, the dial is set at zero and the
subject breaths inhales and exhales normally through her mouth. After a deep inhalation
the subject placed the clean mouthpiece, attached to the hose, in her mouth. Then, she
forcibly exhaled as much air as possible. The number the gauge reached marks the vital
capacity in liters. To eliminate error, one person, who was not a subject, recorded the vital
capacities for the twelve subjects. The subject will repeat the process two more times after
a break. The subject’s average was used for data. A t-test determines the difference
between tall and short females. Standardize variables that can affect the results include the
subjects’ lifestyle, age, smoking habits, health, athleticism and if they are from a high or
low elevation.
Results
Figure 1 compares the mean vital capacity, in liters, for tall and short females. The mean
vital capacity for tall females was 3. 75L and the mean for short females was 3.44L. After
running the 2-sample t-test assuming equal variances, our T value, . 085, was larger than
our alpha value, . 05. A t-test compares the average of the two groups. The variance for tall
females was . 04, compared to short females, . 23. Variance measure how much varies
from the mean of the group.
Figure 1: Effect of height on lung capacity in females.
Discussion
Our results refuted out hypothesis that females’ height affects vital capacity. This is
because our T value, . 085, was slightly larger when compared to our alpha value, . 05. Our
results were not statistically correct because our T value was higher than our alpha.
Taller females have a larger mean of vital capacity than shorter females. However, both tall
and short females have the ability to forcefully exhale large volumes exhaled into the
spirometer. The subjects’ lifestyle and genetics influences their vital lung capacity.
We measured lung capacity with a spirometer. A spirometer is the most common
instrument used to measure lung capacity, but there are some errors involved with it. A
spirometer can become inaccurate if there is too much mucus build up in the hose from
subjects forcefully exhaling into it. We can improve the study by not only measuring vital
capacity, but also inspiratory and expiratory volumes. An inspiratory volume is “the
maximal volume of air that can be inhaled after a normal inspiration” (Elsevier). Expiratory
reserve volume is the volume of air that can be exhaled following normal expiration. These
two volumes added together is the vital capacity. By recording both of these volumes, the
results would be more accurate and the sample size would not have to be changed.
Examining both of these will determine if a subject is healthy or has a breathing disorder
such as asthma. Asthma occurs when the lungs and airways become clogged and
inflamed.
The limited sample size for our study was a major weakness. Limited sample size leads to
lack of classification in the females. The females varied in height, from 5’6” to 5’7” and
from 5’0 to 5’3”. Both groups being examined varied in height. Because of this, the
results were inaccurate. There were a limited number of males so we were unable to
examine the difference between male and female vital lung capacity. Limited sample size
poses other error factors as well. For better, more accurate results, the subjects should be
the same height and weight. Subjects also should be genetically synced and share similar
health patterns. No illnesses, like asthma, that affect breathing should be present. If these
were followed error will significantly decrease.
In order to apply our finding to the general population, we would need more subgroups and
a larger sample size. To improve results, we could examine tall and short females in
different age groups and different lifestyles. Similar lifestyles would be compared and
similar ages would be compared. Doing this would eliminate most factors that cause error
when examining lung capacity and substantially improve results.
Conclusion
Based on our data, we can conclude that height in females does not affect vital lung
capacity. The tall females average 3. 75L and shorter females averaged 3. 44L. However,
our T value, . 085 was larger than out alpha value, . 05.
Literature Cited
Burns, and Smith. 2008. Human Anatomy and Physiology Lab Manual. Page 394.
Elsevier. 2009. Mosby's Medical Dictionary, 8th edition. Inspiratory Reserve Volume.