Respiratory system regulates the volume of gases inhaled and exhaled by a person. This experiment examined the lung volume and capacities and the differences in vital capacities between genders. Furthermore, it investigated several factors that control the respiratory rate and volume, such as pH, O2, and CO2 level. The lung volume helps in studying lung diseases and complications.
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Notably, the average vital capacity (VC) of men was higher than that of women. This might be due to physiological and anatomical differences between males and females, as well as body size. In addition, we examined the effect of re-breathed air in paper bags on breathing rate and tidal volume (TV).
The subjects measured their resting respiration rates and tidal volumes for 2 minutes using a spirometer and a power lab recording system. Next, they measured the respiration rate during breathing in paper bag for 2-3 minutes. Their results indicated a slight increase in respiration rate from 15 to 17 breaths /min and an ideal volume increased sharply from 0.9 to 1.4.
Remarkably, this indicated an increase in CO2 level, which stimulated the increase in the quantity of exchangeable air. As a result, the tidal volume increased even though the rate was low. During hyperventilation CO2, level decreased, which resulted in a decrease in the stimulus for breathing, thus the brain got less signals to re-breathe holding and took longer periods than normally to stimulate breathing from 73 to 119 sec.
The respiratory system’s is tasked with supplying the body with ample O2 and elimination of the waste products of tissue metabolism such as carbon (IV) oxide. The lungs volume is conditioned by inhale and exhale of air. Lung capacity is the sum of Expiratory Reserve Volume (ERV), Tidal Volume (TV), Inspiratory Reserve Volume (IRV), and Residual Volume (RV) (Marieb and Hoehn, 2010).
To understand one’s respiratory situation, Lung volume can be measured to give this information. Additionally, lung volume helps in accurate diagnosis of lung complications. As lung volumes and capacities can vary irregularly, in pulmonary patients they are regularly measured using a spirometer. The outcome can provide definite diagnosis and even distinguish between obstructive pulmonary disorder and restrictive disorder.
These disorders come up when there is loss of total lung capacities and variation function of lungs (Measuring Lung Capacity, n.d.). Upward change in TLC, FRC and RV may occur due to lungs hyperinflation in obstructive diseases. On the other hand, VC, TLC, FRC, and RV are because of restrictive diseases that limit lungs expansion (Marieb and Hoehn, 2010).
Factors such as CO2, O2, and pH in arterial blood affect the rate of respiration. However, CO2 pressure is the main stimulus that controls respiration in human bodies; therefore, any change in CO2 level will lead to an increase of pH level to nine.
Experiment 1: Measurement of Lung Volume and Capacities
Figure one: A Spiro-graphic Record of Respiratory Volume and Capacities
From figure 1
TV=0.5, IRV=1.2 ERV=1.0> ACTUAL VALUE
TV = 0.348 L; IRV = 1.33L and ERV volume =1.27L
The calculation of respiration capacity is as follows:
The inspiratory capacity (IR) =TV+IRV=1.68L
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The functional residual capacities (FRC) = ERV+RV=1.27+1.2=2.47L,
RV is the residual volume =1.2L.
Vital capacities (CV) =TV+IRV+ERV=2.95L
Total Lung Capacities (TLC) TV+ERV+RV=4.15L
Table1: Average Vital Capacity Results for Male and Females
|Average vital capacity for male (L)||5.2|
|Average vital capacity for female (L)||3.1|
Experiment 2: Effects of Re-Breathing Expired Gas on Respiration RateIn table 1, average class result specifies that males had higher vital capacity than females
Table 2: Average class result of respiration rate and tidal volume during control and paper bag breathing.
Respiration rate(breath /min) Tidal volume (L)
|Controlled breathing||Paper-bag breathing||Controlled breathing||Paper-bag breathing|
|17 breath/min||17 breath/min||0.9L||1.7L|
From table 2, the average respiration change remained the same during control respiration. However, average tidal volume changed significantly from average of 0.9 L during control breathing to 1.7L during paper bag breathing.
Expirment3: Effects of Hyperventilation on Breathe Holding Time
Table 3: Average results of breath holding time during and after hyperventilation
Experiment 3: Breathe holding time (seconds)
|During Control (sec)||61|
|After breath-holding (sec)||111|
The average breath holding time increased sharply and almost doubled from 61 during control to 111 seconds after hyperventilation.
The quantity of air that the lungs inhales relies on condition of inspiration, thus there are many respiratory volumes. Firstly, tidal volume (TV) is the air that moves in and out of the lungs with each breath. From the results in figure 2, TV= 348 ml; that of a healthy person is marked at 500 ml (TV).
Secondly, inspiratory reserve volume (IRV) is the total air that one can inhale forcefully after TV and its average is roughly 2100-2300ml. However, our data indicates 1330 ml, which was less than the average. The expiratory reserve volume (ERV) is the air that forcefully exhaled after TV. It is normally 100-1200 ml and from the above data in figure, it is 1270ml.
Finally, residual volume (RV) is the air that remains in the lungs after a complete expiration; it has an average of 1200 ml. RV helps to avoid lungs collapse by keeping the alveoli open (Daubenspeck, 2006). The inspiratory capacity (IC) is the total air inhaled after TV; therefore, it is the sum of TV and IRV.
Vital capacity is more likely to be higher in men than in women. In general, women have anatomical and physiological characteristics, such as reduced vital capacity, airway diameter and lesser diffusion surface compared to men of the same age and height.
These factors influence the exercise response and the low maxima aerobic power, as less muscle in women needs less supply of O2 and release less CO2 (Dahan, n.d.). Obviously, men who are more muscles than the other men have higher aerobic power. For this reason, they require high supply of Oxygen as they release less carbon (IV) oxide.
In paper bag, breathing increased the level of inhaled CO2 and decreased that of O2 . CO2 then dehydrates to form carbonic acid H2CO3 that dissociate to give bicarbonate HCO3– and H+ ions. H+ ions activate the chemoreceptor that sends signals to the medulla in the brain’s stem hence increasing the rate and depth of breathing as shown in table 2. The respiration rate increased from 15 to 17 breath/ min.
The immediate change in the level of CO2 is the main cause for rise in pH. Although the rate of the breathing is low, TV significantly increased as indicated in table 2 from 9 to 1.7L (Dahan, n.d.).
During hyperventilation, the CO2 level dropped in alveoli capillaries and pH level rose, but O2 remained the same because nearly 98% of O2 is carried by haemoglobin, which shows that O2 gas saturates haemoglobin during normal breathing and hyperventilation. Markedly, there was a strong relationship between CO2 and hyperventilation as CO2 triggers respiration in the body.
When a person hyperventilates, he/she exhales a great amount of CO2, thus the brain gets less signal; it increases a person’s breathing speed coupled with tiredness. This explains the great difference between breath holding in a class result during normal breathing (73 sec) and 119 seconds after hyperventilation. Therefore, when a person hyperventilates, dizziness and fainting occur.
Dahan, A. (n.d.). Factors Influencing the Control of Breathing, European Society for Intravenous Anaesthesia. Web.
Daubenspeck, J. A. (2006). Mechanical Factors in Breathing Pattern Regulation in Humans. Biomedical and Life Sciences, 9(5 – 6), 409-424. Web.
Marieb, E. N. & Hoehn, K. (2010). Human Anatomy and Physiology (8th ed.). Redwood City, Calif.: Benjamin/Cummings.
Measuring Lung Capacity. (n.d.). The Biology Corner. Web.