BIOLOGY LAB REPORT

TITLE : MEASURING LUNG CAPACITY USING PORTABLE SPIROMETER

PREPARED BY :

I/C NUMBER :

STUDENT ID :

GROUP :

LECTURERS NAME :

PRACTICAL DATE :

SUBMISSION DATE :

Abstract

Lung capacity varies with individual depending on certain criterias such as age, gender and body size. Lung capacity can be calculated using vital capacity (VC), tidal volume (TV) and expiratory reserve

volume (ERV). This experiment was conducted to investigate breathing using a dry portable

spirometer. Each students are given disposable mouthpiece with spirometer (shared in a group) to

measure VC, TV and ERV. This is done by exhaling air through the mouth piece in different ways

(refer procedure) and record the reading. Using the data obtained, other measurements such as IC, IRV

and TLC were obtained (refer formula below). The experiment is done by manipulating bodys state, at rest and after exercise.

Introduction

1. The Lungs(1)

The lungs are the main organ of the body responsible for gas exchange, namely the transfer of oxygen

into the body and the transfer of carbon dioxide out of the body. The biomechanical properties of the

lungs are integral in how well they can transfer air in and out. The gas exchange of oxygen and carbon

dioxide in the body takes place in three steps.

Ventilation (refers to the moving air in and out of the lungs) occurs.

Gas diffusion and uptake occurs.

The gas is transported by the blood.

The muscles that control respiration create a difference in lung pressures. This pressure difference,

which is also a function of the elasticity of the lungs, causes air to flow. The diaphragm is the main

muscle that is used for breathing. When the diaphragm contracts it causes the lungs to inflate and the

thoracic cavity becomes enlarged. As a result, the pleural space in the chest cavity enlarges. This

increase in space volume causes a decrease in pressure which causesthe lung to expand and fill with

air. This is an example of Boyles Law in action. Boyles Law states that

For a constant temperature, the volume of any gas varies inversely with the pressure.

Pressure 1/ Volume = Constant

2. The measurements of breathing

Figure 1: Descriptions and average measurements(2)

Figure 2: Indicating measurements(3)

3. Spirometer

Figure 3 : Usage of spirometry(4)

Spirometry is the classic pulmonary function test, which measures the capacity of the lungs to exhale

and inhale air, and the amount of air left remaining in the lungs after voluntary exhalation. It can

monitor quiet breathing and thereby measure tidal volume, and also trace deep inspirations and

expirations to give information about vital capacity. The instrument use for this procedure is called

spirometer. This device also considered as an essential tool in the detection of chronic

obstructive pulmonary disease, which includes emphysema and chronic bronchitis. In addition,

spirometers are typically used to track the breathing capability of individuals with respiratory

ailments such as asthma. Spirometers are also used to estimate limits of activity for people with

respiratory problems.

Figure 4: Portable dry spirometer with mouthpiece(5)

The normal, healthy values measured by the spirometer for the amount of air exhaled vary from

person to person. Your results are compared to the average expected in someone of the same age,

height, sex, and race, according to the National Heart, Lung, and Blood Institute (NHLBI). However, if

the values fall below 85 percent of the average, it may indicate a lung disease or other airflow

obstruction. If a person has abnormal spirometer measurements, he/she may be referred for other

lung tests to establish a diagnosis.

Figure 5: Spirometer reading(6)

In this experiment we use the Carolina Portable Dry Spirometer which provides a simple but accurate

means for measuring pulmonary volumes and capacities in the laboratory. The principle of operation

is similar to that of a rotametric dry gas meter. Since the water canister associated with a

conventional wet spirometer is not used, setup time and the mass associated with spirometry are

virtually eliminated. (7)

Objective

To measure students lung capacity using a portable spirometer.

Problem Statement

What is the total lung capacity of the student? Does body state effect the total lung capacity or the

breathing rate?

Hypothesis

Total lung capacity of a student depend the bodys state (rest/active). This can be calculated by

obtaining tidal volume, vital capacity and expiratory reserve volume.

Variable :

Types of Variables Ways to control the variables

Manipulated Variable:

State of body

Measurement were taken at rest and after exercise

Responding Variables:

Vital Capacity, Tidal Volume, and Expiratory

Reserve Volume of the Students

Following procedure below, find VC, TV and

ERV via reading the scale on the dry spirometer.

Fixed Variables:

Age

Body size

Same age student was examined.

Same student was used.

Apparatus

Spirometer, disposable mouthpiece.

Materials

Tissue, human subjects (students).

Procedure

1. A mouthpiece is attached to the side limb of the spirometer.

2. The spirometer dial is rotated until the needle is aligned with the 0 mark. The dial, marked in

increments of 100cc, will register up to 7.0 liters of expired air.

3. The spirometer is held by the base/ put on a table so that the air holes are not blocked and in a

horizontal position.

4. Nostrils are pinched with free hand to keep air from escaping through the nose. The breathing

maneuver for vital capacity, tidal volume and expiratory reserve volume is performed.

a) Vital Capacity (VC)

i. The nasal airway is closed by pinching the nose.

ii. The subject inhaled as deeply as possible and exhaled all of the air through the spirometer.

iii. The value shown on the spirometer gauge is recorded

b) Tidal Volume (TV)

i. Nose is pinched. The spirometer mouthpiece is placed loosely between lips, and breathed

normally through the corner of the mouth for several breaths.

ii. After a regular breathing pattern is established, five successive normal breaths are exhaled into

the spirometer.

iii. The meter reading for the total of five breaths are recorded and divided by 5 to calculate the

average tidal volume at rest.

c) Expiratory Reserve Volume (ERV)

i. Nose is pinched. The spirometer mouthpiece is placed between lips, and breathed normally

through the corner of the mouth for several breaths.

ii. After a regular breathing pattern is established, remaining air is expired forcefully as much as

possible into the spirometer.

iii. The value shown on the spirometer gauge is recorded

5. Both Tidal Volume and Expiratory Reserve Volume experiments were repeated thrice.

6. The results of the experiments are used to calculate value for Total Lung Capacity (TLC),

Inspiratory Reserve Volume (IRV), and Inspiratory Capacity (IC) using formula below.

For IRV : VC - ( TV + ERV )

For IC : VC - ERV

For TLC : VC + RV( 900 cc for female)

7. All the steps above are repeated on the subject after undergo exercise.

Safety precaution

In order to avoid any accident or injury during the experiment in laboratory, the precautionary

steps should be taken and applied. Wearing lab coat and a pair of suitable shoes are compulsory

when conducting an experiment in the lab at all times to protect the skin and clothing from spillage

of any chemical substance. Hands need to be thoroughly washed before and after performing the

experiment to avoid infection of saliva. Furthermore, the glassware such as spirometer should be

handled with full care because they are fragile. After using the mouthpiece at the end of

experiment, they should be rinsed properly and returned back to their respective beakers. The same

should be done with the spirometer, where it should be cleaned and dried before place it inside

its box. Student should take care of surrounding so that they dont collide with any glassware while

undergoing exercise.

Risk Assessment

The spirometer base is a moisture trap which should be cleaned frequentlyto avoid inaccuracy in

results. The spirometer should be hold upright horizontally or best put on a flat surface that is

leveled with bodys sitting position and screw the top portion counter-clockwise to separate the

two parts. Wipe the moisture trap with a tissue every time after finish one stage of experiment and

before storing the spirometer. Besides that, subjects must not cover up the small holes which are at

the side of the upper body of the spirometer with hands.

Results

Vital Capacity (VC)

Trial 1 Trial 2 Trial 3 VC Highest Volume

Rest 2500 2900 3100 3100

After Exercise 2700 3200 3300 3300

Tidal Volume (TV)

Total for Five Breaths Average

Rest 2200 440

After Exercise 2275 455

Expiratory Reserve Volume (ERV)

Trial 1 Trial 2 Trial 3 Average

Rest 2000 2200 2100 2100

After Exercise 1900 2500 2200 2200

Inspiratory Reserve Volume (IRV): VC (TV + ERV)

Rest 3100 (440 + 2100) = 600

After Exercise 3300 (455 + 2200) = 645

Inspiratory Capacity (IC): VC ERV

Rest 3100 2100 = 1000

After Exercise 3300 2200 =1100

Residual Volume (RV)

Rest 900

After Exercise 900

Total Lung Capacity (TLC): VC + RV

Rest 3100 + 900 = 4000

After Exercise 3300 + 900 = 4200

Table 1 : VC, TV, ERV, IRV, IC, RV and TLC of student at rest and after exercise state

Data Analysis

Table 1 above show the comparison done between two different body state (rest and after

exercise) to calculate vital capacity (VC), tidal volume (TV), expiratory reserve volume (ERV),

inspiratory reserve volume (IRV), inspiratory capacity (IC) and total lung capacity (TLC). After

exercise, we can see there are some different compared to the value before exercise (rest) for the

student. It can be see that overall all measurement increase except residual volume which was kept

constant. The highest increase can be seen in IRV and VC while the smallest increase can be noted in

TV.

DISCUSSION

From this experiment, it can be seen that the state of body influences the breathing rate of the

student. The ventilation rate is higher after exercise compared to rest state indicating that more air is

inhaled after exercise to fulfill the lungs.

During rest, amount of oxygen needed by the body is lesser since oxygen is needed to respire

thus ventilation rate is smaller. During exercise, the presence of the anatomical dead space of the

respiratory system (air in the nose, mouth, larynx, tracheas, bronchi and bronchioles) cause the depth

of breathing increases. This air reaches the alveoli first upon inspiration. This air also has a higher

concentration of carbon dioxide because of its prolonged exposure to the tissues. Therefore, as the

depth of a breath increases, the proportion of "fresh air" that gets to the alveoli also increases and the

result is rate of gaseous exchange will also increase.

Vital capacity is how much the lungs can breathe in, so it will not change, unless lung capacity

changes. Exercise increases vital capacity because the lungs need more oxygen to supply the muscles

with vital nutrients (oxygen and glucose) and the intense the exercise the more nutrients needed. The

lungs expand during this to account for the extra need hence increasing the vital capacity. This is

positively correlated with the data in Table 1.

When exercising the tidal volume also increase because the student is breathing at a faster rate

and their muscles are using up the oxygen at a quicker rate. Hence more oxygen is needed and these

will increase the tidal volume to allow more oxygen to be consumed and meet the muscles oxygen

demands. The residual volume is kept control because it cannot be measured and normally stays the

same disregarding body state. Thus, I can be seen that exercise increases total lung capacity at the end

of exercise.

Limitations and Sources of errors

There are several sources of error and limitations that have been identified throughout this experiment.

The way student exhale. The strength given while exhaling out the air is different in term of

strength. This is because, the student is unable to exhale as usual but blow which contribute to

the inaccuracy of data.

The exercise done by student is not fixed in term of the type of exercise and duration of time.

This is because the student needed to complete the experiment in the given time and space for

exercise to be done is too small and not safe.

The experiment is not compared with the other students or not repetitive measurement is taken.

Thus, the data is unreliable.

Conclusion

Body state of person do affect vital capacity (VC), tidal volume (TV), expiratory reserve volume

(ERV), inspiratory reserve volume (IRV), inspiratory capacity (IC) and total lung capacity (TLC).

Thus, the hypothesis is accepted.

Further Investigation

Another experiment can be carried out using same steps but by manipulating the body size of student.

References

1. Gan W.Y . 2007. Biology SPM Success. Edition 4. 287.p.Shah Alam : Oxford Fajar Sdn.Bhd.

2. http://www.sciencebuddies.org/science-fair-projects/project_ideas/HumBio_p009.shtml. Accessed on 8

th October 2012

3. http://www.brianmac.co.uk/diagram spirometer trace.htm. Accessed on 8th October 2012

4. http://www.angela.co.uk/diagram spirometer use adam.htm. Accessed on 8th October 2012

5. http://www.gogoscience _spirometer diagram/diagram spirometer.Accessed on 8th October 2012

6. http://lanwebs.lander.edu/faculty/rsfox/ireads/spirometertrace.html. Accessed on 8th October 2012

7. Portable Dry Spirometer Instructions- 69-2670. Carolina Biological Supply Company.2700, York Road,Burlington, North Carolina