INTERNATIONAL EDUCATION CENTRE (INTEC)

A-LEVEL MEDICINE

BIOLOGY LABORATORY REPORT

NAME : YIN ZHENG DAO

NRIC : 910902-02-5059

GROUP : 10M7

STUDENT ID : 2009628992

TITLE : Investigating human breathing

DATE : 22nd September 2010

LECTURER : MR. MANOHARAN

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Problem StatementHow does the lung capacity differ before and after exercise?

ObjectivesTo determine lung capacity.

Introduction

Respiration is defined as the transport of oxygen from the outside air to the cells within tissues and the transport of carbon dioxide in the opposite direction. This is in contrast to the biochemical definition of respiration, which refers to cellular respiration: the metabolic process by which an organism obtains energy by reacting oxygen with glucose to give water, carbon dioxide and ATP which is used as energy. Although physiologic respiration is necessary to sustain cellular respiration and thus life in animals, the processes are distinct: cellular respiration takes place in individual cells of the animal, while physiologic respiration concerns the bulk flow and transport of metabolites between the organism and the external environment.

In unicellular organisms, simple diffusion sufficient for gas exchange: every cell is constantly bathed in the external environment, with only a short distance for gases to flow across. In contrast, complex multicellular animals such as humas have a much greater distance between the environment and their innermost cells, thus, a respiratory system is needed for effective gas exchange. The respiratory system works in concert with a circulatory system to carry gases to and from the tissues.

Vital capacity (VC) is the maximum amount of air a person can exhale after filling his lungs to the maximum extent possible. The anatomical build of the subject, the position of his body during the measurement, the strength of the respiratory muscles, and the distensibility of the lungs and rib cage are the major factors which affect VC. The average VC in a young adult male is approximately 4.6 L, and in the young adult female about 3.1 L, significant variance from thses values might be observed.

When measuring VC, the subject should sit as straight as possible, holding a spirometer with mouthpiece attached. After setting the needle at the ‘O’ mark, the subject occludes the nasal airway by pinching the nose, inhales as deeply as possible, and exhales all of the air through the spirometer. Care must be taken to avoid any leakage of air around the edge of the mouthpiece and it is best to perform the maneuver with less than maximum force, although the lungs must be emptied as completely as possible. The vales shown on the spirometer gauge are recorded and readings are repeated to get the average. The largest volume of gas exhaled in a single trial will be the subject’s VC.

Tidal volume (TV) is the amount of air inspired and expired during a single normal breath. In a young adult male, TV is normally about 500 cc. The subject should rest quietly

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for 5 minutes before making the tidal volume measurement. The recording position is the same as for cital capacity in the preceding exercise. The subject pinches his nose, places the spirometer mouthpiece loosely between his lips, and breathes ‘normally’ through the corner of his mouth for several breaths. The diameter of the spirometer mouthpiece is too small to inhale through comfortably. After a regular breathing pattern is established, the subject exhales five normal successive normal breaths into the spirometer. It is necessary to exhale with moderate force to activate the spirometer mechanism. Record the meter reading for the total of five breahts and divide by 5 to calculate the average tidal volume at rest.

Expiratory Reserve Volume (ERV) is the maximum amount of air that can be expelled from the lungs by exhaling forcefully after the end of a normal tidal expiration. ERV averages about 1100 cc in the young adult male. The procedure for measuring ERV is similar to that for tidal volume. The subject sits with his nose pinched and the mouthpiece positioned lossely between his lips while he takes several quiet breathes without exhaling through the spirometer. When a regular breathing pattern is established, the subject exhales normally, then seals his lips around the mouthpiece and forcefully expires as much of the remaining air as possible into the spirometer. The values shown on the spirometer gauge are recorded, just like the measurement procedures as mentioned before.

Residual Volume (RV) is defined as the amount of air remaining in the lungs after maximum forced expiration and it cannot be measured using the spirometer. Its value is usually assumed to be 1200 cc for a young adult male and 900 cc for a young adult female.

Inspiratory Reserve Volume (IRV) is the amount of air that can be inhaled in excess of normal inspiration during quiet breathing. The IRV is calculated by adding the average values for TV and ERV and subtracting the total from the measured VC (IRV = VC – [TV + ERV]. Among young adult males of average size, this volume is approximately 3000 cc.

Inspiratory Capacity (IC) is the maximum amount of air that can be inhaled by subtracting ERV from VC (IC = VC – ERV). Finally, Total Lung Capacity (TLC) is the maximum volume of air that the lungs can hold when distended to the greatest possible extent. Its value is calculated by adding the values of VC and RV.

Figure 1 - Spiropet

A spiropet is used to measure lung capacity without using water. It is small, lightweight, and easy to handle and offers a broad measurement range of 1,000–7,000cc.

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HypothesisThe tidal volume and vital capacity of an individual increases after exercise.

MaterialsTissue paper, subject.

ApparatusSpiropet, interchangeable mouthpiece.

ProceduresA. Measuring vital capacity (VC) at rest

1. The end of the mouthpiece was set to the nozzle of the spiropet.2. The subject sat as straight as possible, holding the spirometer with the mouthpiece

attached to it.3. The spiropet was then held by one hand and the indicator point set to be at zero. If

the indicator does not point at zero, it can be adjusted by moving the upper outer ring to right or left.

4. Deep inhalation was then carried out, stretching the body upward in the process.5. The mouthpiece was set between lips when the lungs of the subject was full.6. Exhalation of all of the air was carried out strongly at one go.7. After exhaling, the measurement was read on the spiropet gauge. The experiment is

repeated another 2 times. The largest volume of gas exhaled in a single trial will be taken as the subject’s VC value.

B. Measuring tidal volume (TV) at rest 1. The spiropet mouthpiece was placed loosely between the lips of the subject.2. The subject then breathed normally through the corner of his mouth or

initiate several breaths.3. The subject exhales five successive normal breaths into the spiropet. 4. The meter reading for the total of five breathes were taken and divided by 5

to obtain the average value of TV at rest.

C. Measuring expiratory reserve volume (ERV) at rest 1. Steps 1 to 4 of experiment B were repeated for this step.

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2. When a regular breathing pattern is established, the subject exhaled normally, then sealed his lips around the mouthpiece and forcefully expired as much of the remaining air as possible into the spiropet.

3. The experiment was repeated for another two times and an average reading was obtained.

D. Measuring inspiratory reserve volume (IRV), inspiratory capacity (IC), residual volume (RV) and total lung capacity (TLC) at rest

1. Based on values of VC, TV and ERV obtained from experiments A, B and C, the values for IRV, IC and TLC can be calculated respectively based on the following formulas :

2. As RV is not measurable, it was assumed that RV for males is 1200cc and that of female is 900cc.

E. Measuring VC after physical exercise 1. A form of exerting exercise was carried out by running up and down the

staircase for about 15 times.2. Once the subject starts panting, steps 7 to 9 were repeated immediately.

F. Measuring VC after physical exercise 1. A form of exercise was carried out by running up and down the staircase for

about 15 times.2. Once the subject starts panting, steps 5 and 6 were repeated immediately.3. At the end of the experiment, the water drops and saliva condensed in the

inside of the spiropet were wiped using tissue paper so that it remains clean for the next usage.

Result

Vital capacity (VC), cc

Trial 1 Trial 2 Trial 3 Highest value of VC

3800 3700 3900 3900

Table 1.1- Vital capacity (VC) at rest

Tidal volume (TV), cc Total for five breaths Average reading

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2000 = 400

Table 2.1- Tidal volume (TV) at rest

Expiratory reserve volume

(ERV), cc

Trial 1 Trial 2 Trial 3 Average reading

1800 1800 1800

= 1800

Table 3.1- Expiratory reserve volume(ERV) at rest

Components of lung volume Reading (cc)

Inspiratory reserve volume (IRV)

= VC - (TV + ERV)

3000 - (1800 + 400)

= 1700

Inspiratory capacity (IC)

= VC - ERV

3900 - 1800

= 2100

Residual volume (RV) Assumed RV = 1200 for males

= 900 for females

Total lung capacity (TLC)

= VC + RV

3900 + 12=

= 5100

Table 4.1- Inspiratory reserve volume (IRV), inspiratory capacity (IC), residual volume (RV) and total lung capacity (TLC) at rest

Vital capacity (VC), cc

Trial 1 Trial 2 Trial 3 Highest value of VC

4200 4200 4100 4200

Table 5.1- Vital capacity (VC) after exercise

Tidal volume (TC), cc Total for five breaths Average reading

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2400 = 480

Table 6.1 -Tidal volume (TV) after exercise

Discussion

Evaluation of Data

The changes in lung volume during breathing processes are investigated using the spirometer. In this investigation, a spiropet is used to measure the lung capacity. A spiropet is a precision instrument with broad measurement range, ranging from 1000cc to 7000cc. It has some advantages over the conventional tank-type spirometer which gives simplicity to the way of handling it during the procedures. Being light weight and small size, it is also a dry spirometer which measures the lung capacity without using water. That way, the setup time and mess associated with spirometry is prevented.

Table 1.1 shows the vital capacity (VC) of the subject at rest. The three readings obtained are 3800cc, 3700cc and 3900 cc being the highest VC value. Table 2.1 meanwhile shows the tidal volume (TV) of subject at rest. Five consecutive readings and a total of 2000cc and thus, an average TV value of 400cc . Table 3.1 gives the expiratory reserve volume (ERV) of subject.

Based of the VC, TV and ERV values, another few components of lung volume can be calculated. The inspiratory reserve volume (IRV) is the amount of air that can be inhaled in excess of normal inspiration during quiet breathing, and is 1700cc. Inspiratory capacity (IC) on the other hand is the maximum amount of air that can be inhaled from the normal end expiratory level, calculated by subtracting ERV from VC, giving a lower than expected reading of 2100 cc. As residual volume cannot be measured, it can be assumed for to be 1200cc for a young adult male and 900cc for a female. Finally, the addition of VC and RV gives the total lung capacity (TLC), which is the maximum volume of air that lungs can hold when distended to the greatest possible extent. The TLC value is normally around 6000cc . The value obtained in this experiment, though is 5100cc.

Table 5.1 and 6.1 shows the VC and TV values after physical exercise which are 4200cc and 480cc respectively. Comparing those values to the ones in Table 1.1 and 1.2, it also be said that exercise increases the vital capacity and tidal volume of an individual. This results is parallel with what were being expected and can be explained using some biological principles. The level of carbon dioxide in blood plays the most important role in controlling out breathing rate. In the course of an exercise, the impulses from the cortex of the brain which consciously recognizes movement stimulates the respiratory centre in medulla

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oblongata. Then, respiratory muscles are stimulated and the rate and depth of ventilation are also increased. The demand for oxygen by working muscles increases and more carbon dioxide is produced and transported in the blood. A fall in pH level is then detected by chemoreceptors which in turn, send impulses to the inspiratory centre. Finally, the inspiratory centre sends nerve impulses to the intercostals muscles and diaphragm, causing an increase in their contraction rates, making them contract harder and more frequently resulting is the increase in vital capity and tidal volume of lungs.

Based on the results, we can come to a conclusion that exercises increases the vital capacity and tidal volume of the subject.

Sources of Errors and Ways to Overcome Them / Safety Precautions

Some errors in the experiment will cause the result to be less accurate. One possible source is during the usage of the spiropet. Spiropet may not have been kept still when used. Consequently, the vanes cannot revolve evenly and readings obtained will not be of high accuracy. The spiropet should actually be kept horizontal by holding it firmly with one hand. The subject’s fingers might have also accidentally covered up a few of the small holes which are at the side of the upper body of the instrument. Besides that, water drops and saliva might condense on the inside of the spiropet causing a lost in accuracy. In this experiment, the spiropet is only wiped at the end of the experiment. To avoid this error, the inside should be cleaned with tissue paper once in every five measurements.

The leakage of air around the edge of the mouthpiece might have also caused the exhaled air to escape to the surrounding instead of entering the spiropet. Hence, the subject should set the mouth carefully and tighly between his lips so as to avoid any leakage of air. The difference in way of breathing out when taking measurements of components of lung volume using the spiropet could also affect the accuracy of the experiment. Exhalation with too little force will not be enough to activate the spiropet mechanism, causing a lower reading while too much force may affect the accuracy of readings as well. Thus, it is always better to perform moderate force during the experiment.

Comparing results of other subjects, there will be a significant variation in them. The measurements of TC and ERV are repeated after exercising so as to investigate the lung capacity at rest and after physical exercise. Though having said that, the frequency of exercise is not the only factor affecting the lung capacity of an individual. Other factors include age, body size, health condition, gender, environment, genetics and others. That is why the values will show slight variation as the other factors are not kept constant except the age. One of the limitations in this experiment is the genetics of the subject which is a factor which cannot be controlled. Genetics affect the lung capacity of an individual. Before conducting the experiment, the information on the genetic make-up of each individual is

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unknown. This leads to variation in the results obtained by different individuals as different subjects.

Zero error is another possible error that should be avoided when rotating the spiropet dial until the needle is aligned with the ‘O’ mark by calibrating with the eyes level perpendicular to the calibrated scale. Air holes of the instrument should not be blocked. The base of the spirometer is a moisture trap and should be wiped using tissue paper only.

As for safety precautions, fully-covered shoes should be worn in order to avoid any spillage of any solution on our feet. Long hair should be tied up as well so that disturbances while conducting the experiment would not take place. Suitable precautions should be taken when using the spiropet as it is a precision instrument and is of a high costs.

Further works

Apart from that, further investigation can also be carried out to such as :

To investigate the effect of age on lung capacity.

To investigate the effect of body size on lung capacity.

ConclusionVital capacity and tidal volume of an individual increases after exercise. Thus, the hypothesis is accepted.

References Ann Fullick, Edexcel A2 Biology, (Harlow, Pearson Education Limited, 2009)

C J Clegg, Edexcel Biology for A2, (London, Hodder Education, 2009)

http://en.wikipedia.org/wiki/Lung_volumes, accessed 26th September 2010

http://en.wikipedia.org/wiki/Human_lung, accessed 26th September 2010

http://www.wikihow.com/Increase-Your-Lung-Capacity, accessed 26th September 2010

http://www.biologycorner.com/worksheets/lungcapacity.html, accessed 26th

September 2010

http://www.nlhep.org/spirom1.html, accessed 26th September 2010