Respi Physio Ex

Respiration is a vital process for the survival of every organism. This process includes the passage of air into and out of the lungs and a result of skeletal muscle contraction, otherwise known as ventilation, and the transport of oxygen and carbon dioxide by the blood between the lungs and tissues. This important exchange of gases in the body is taken part by the respiratory system through working cooperatively with the circulatory system. The primary role of the heart is the pumping of deoxygenated blood to pulmonary capillaries. As the blood enters the pulmonary circuit, gas exchange occurs between the blood and the alveoli, hence, oxygenation oxygenation of the blood happens. The oxygenated blood is then pumped by the heart to the tissues that are actively metabolizing. In connection to, the main product of metabolism, which is CO 2 is continuously diffusing into the blood and returns to the heart for another cycle of oxygenation. There are two processes involved during respiration, inspiratory and expiratory processes, both of which can be further classified as quiet and forced. These two processes involve several muscles such as diaphragm, external intercostal muscles, internal internal intercos intercostal tal muscles, muscles, and abdomin abdominal al muscles. muscles. Diaphra Diaphragm gm is a dome-sh dome-shaped aped muscle muscle which which divides divides the thoracic thoracic and abdomin abdominal al cavities cavities.. During During inspira inspiration tion,, the diaphragm descends and the external intercostal muscles contract, thereby increasing the volume of air in the thoracic cavity, which in turn reduces the pressure in the thoracic cavity. This active process allows atmospheric gas to enter the lungs and usually requires expenditure of energy in the form of ATP. On the contrary, expiration is a passive process wherein it involves the relaxation of the muscles. During this process, the diaphragm and the external intercostal muscles relax relax,, there thereby by incre increas asing ing the the pressu pressure re in the the thora thoracic cic cavit cavity y as the the volum volume e of air  decre decreas ases. es. This This proc proces ess s facili facilita tates tes forcin forcing g air air out out of the lungs. lungs. Howe Howeve ver, r, during during activities like running, expiration turns to be an active process involving the contraction of internal intercostal muscles and abdominal muscles. One important parameter to measure the efficiency of the respiratory process is the minute ventilation which measures the amount of air that flows into and out of the lungs in a span of a minute. It can be obtained by using the formula, Minute ventilation= frequency of breathing (bpm) x tidal volume (500mL) This This activi activity ty aims aims to under understa stand nd the the basic basic princi principle ples s in the mecha mechanic nics s and and regulation of the respiratory system. Also, to understand the different concepts in a simulated lung so as to understand how the respiratory system works and adapts to these different simulations.

ACTIVITY 1: MEASURING RESPIRATORY VOLUMES AND CALCULATING CAPACITIES

The objectives of this activity include, first, to understand the concepts underlying the process of ventilation, phases of respiration, the muscles involved in the respiratory process, respiratory volumes, and capacities. Second, is to identify the roles of skeletal muscles in the mechanics of breathing. Third, is to understand the changes in volume and pressure in the thoracic cavity during the breathing process. Lastly, is to understand the effects of airway radius on resistance, and their coupled effect on airflow. Breathing involves two phases namely, inspiration and expiration respectively. Both inspiration and expiration are classified either quiet or forced. In quiet inspiration, the inspiratory muscles relax and the diaphragm ascends superiorly as the chest wall moves inward, the thorax returns to its normal shape as given by its elastic properties. This process normally moves approximately 0.5 L of air into and out of the lungs and this value varies with sex, age, physical condition, and respiratory needs. Table 1. Muscles involve during respiration Inspiration Diaphragm External Intercostal Muscles

Expiration (Active) Abdominal Muscles Internal Intercostal Muscles

There are different respiratory volumes and capacities that are set as parameters in the evaluation of the respiratory process. Tidal volume (TV) is the amount of air  inspired and expired with each breath during quiet respiration and is approximately equal to 500 ml. Inspiratory reserve volume (IRV) is the amount of air that can be forcefully inspired and is approximately 3100 mL in male and 1900 in female. Expiratory reserve volume (ERV) is the amount of air that can be forcefully expired and is approximately 1200 mL in male and 700 mL in female. Residual volume (RV) is the amount of air remaining in the lungs after forceful and complete expiration and is approximately 1200 mL in male and 1100 mL in female. Total lung capacity (TLC) is the maximum amount of air contained in lungs after a maximum inspiratory effort and be calculated using the formula, TLC= TV + IRV + ERV + RV and is approximately 6000 mL in male and 4200 mL in female. Vital capacity (VC) is the maximum amount of air that can be inspired and expired through maximal effort and can be calculated using the formula,

VC= TV + IRV + ERV and is approximately 4800 in male and 3100 in female. Forced vital capacity (FVC) is the amount of air that can be expelled after taking the deepest possible inspiration and forcefully doing expiration completely and rapidly. Forced expiratory volume (FEV 1 ) is a measure of the percentage of the vital capacity that is expired in one second and usually ranges from 75-85% of the vital capacity. Results: Radius

5.00

Flow (L/min ) 7,485

TV

ERV

IRV

RV

VC

FEV1

TLC

Breath Rate

499

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---

---

---

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15

Radius

5.00

Radius

4.50

Flow (L/min ) 7,500

Flow (L/min ) 4,920

TV

ERV

IRV

RV

VC

FEV1

TLC

Breath Rate

500

1,200

3,091

1,200

4,791

3,541

5,991

15

TV

ERV

IRV

RV

VC

FEV1

TLC

Breath Rate

328

787

2,028

1,613

3,143

2,303

4,756

15

Radius

4.00

Radius

3.50

Flow (L/min ) 3,075

Flow (L/min ) 1,800

TV

ERV

IRV

RV

VC

FEV1

TLC

Breath Rate

205

492

1,266

1,908

1,962

1,422

3,871

15

TV

ERV

IRV

RV

VC

FEV1

TLC

Breath Rate

120

288

742

2,112

1,150

822

3,262

15

Radius

3.00

Flow (L/min ) 975

TV

ERV

IRV

RV

VC

FEV1

TLC

Breath Rate

65

156

401

2,244

621

436

2865

15

Table 2: Summary of results

 As seen in the results, as the radius of the airway is gradually reduced from 5.00, the flow rate also decreases. This can be explained by the increased resistance in smaller radius. A reduction in the airway radius would mean an increased resistance. This resistance will tend to constrict the airway thereby, limiting and reducing the amount of air that can flow in the airway, as seen in the reduced flow rate. Consequently, all of the measured parameters also decreased with the decreasing radius except for the residual volume. As seen on table 2, as the radius of  the airway is reduced, the residual volume increases. The residual volume is known to be the amount of air that remains in the lungs after forceful and complete expiration, as the airway constricts because of the decreased radius and increased resistance, the passage of air is limited and most of the inspired air remains in the lungs and is exhibited by increased residual volume. In addition to, the breath rate remained constant all throughout since there is no need for compensatory increase or decrease in respiratory rate. In summary, it can be concluded that the radius is inversely proportional to resistance but is directly proportional in the flow rate. And such relationship is exactly exemplified in a decrease in TV, ERV, IRV, VC, FEV 1, and TLC and an increase in RV.

ACTIVITY 2: Comparative Spirometry

The objectives of this activity include, first, to understand the terms spirometry, spirogram, emphysema, asthma, inhaler, moderate exercise, and heavy exercise. Second, is to observe and compare spirograms collected from healthy patients to that of  emphysema patients. Third, is to observe and compare spirograms collected from healthy patients to those of suffering from asthma attacks. Fourth, is to observe and compare the spirogram collected from an asthmatic patient while suffering an acute asthma attack to that taken after the patient uses an inhaler for relief. And lastly, to observe and compare spirograms collected from volunteers who had undergone moderate to heavy exercise. In evaluation of the volume inspired and expired over a specified period of time, a device known as spirometer is usually used. In doing so, there are different classifications of breathing that had been identified. First is emphysema breathing, it is due to loss of elastic recoil in the lung tissue, increased airway resistance, and characteristic changes in the lungs such as it is more flimsy, exerts less anchoring on surrounding airways, over compliance, expands easily, and inability to passively recoil and deflate. In patients suffering from emphysema, they exemplify the following characteristics: a greater effort required to expel air, a noticeable exhausting muscular  effort in expiration, and a slow expiration.  Another classification would be acute asthma attack breathing which is primarily due to bronchiole smooth muscle spasms which result in the airway constriction. In addition to, it may also be caused by clogged airway with thick mucus secretions and increased airway resistance. The inflammatory response may be triggered by allergens,

extreme temperature changes, and exercise. The most commonly used form of relief is the use of an inhaler which contains a smooth muscle relaxant that consists of β 2 agonist and acetylcholine antagonist. This results in a relieved bronchospasms and bronchiole dilation. Moreover, it may also contain corticosteroid which is an antiinflammatory agent that reduces airway resistance.  And the last classification is breathing during exercise. In moderate aerobic exercise, there is an increased metabolic demand and is compensated by an increase in the rate of breathing and increased tidal volume. Consequently, during heavy exercise, there is also increase in the metabolic demand and is also compensated by an increase in the rate of breathing and increased tidal volume up to the maximum tolerable units. Results: Patient Type Normal

TV

ERV

IRV

RV

FVC

TLC

FEV1

500

1,500

3,000

1,000

5,000

6,000

4,000

Patient Type Emphysema

Patient

TV

TV

ERV

IRV

RV

FVC

TLC

FEV1

500

750

2,000

2,750

3,250

6,000

1,625

ERV

IRV

RV

FVC

TLC

FEV1

FEV1 (%) 80%

FEV1 (%) 50%

FEV1

Type Acute Asthma Attack

Patient Type Asthma Attack Plus Inhaler 

Patient Type Moderate Exercise

Patient Type Heavy Exercise

300

750

2,700

2,250

3,750

6,000

1,500

TV

ERV

IRV

RV

FVC

TLC

FEV1

500

1,500

2,800

1,200

4,800

6,000

3,840

TV

ERV

IRV

RV

FVC

TLC

FEV1

1,875

1,125

2,000

1,000

ND

6,000

ND

TV

ERV

IRV

RV

FVC

TLC

FEV1

3,650

750

600

1,000

ND

6,000

ND

(%) 40%

FEV1 (%) 80%

FEV1 (%) ND

FEV1 (%) ND

Table 3: Summary of results on the classification of breathing and their  parameters.

 As compared to the normal patient, the tidal volume of the patient with an acute asthma attack is lower. Apparently, the patient suffering from emphysema and acute asthma attack plus inhaler has the same tidal volume to that of the normal patient while those who had done exercise has greater tidal volume. In the expiratory reserve volume, all of the patients had shown a lesser ERV compared to the normal patient. Interestingly, the lowest ERV is exemplified by the patients who did a heavy exercise, those with acute asthma attack and emphysema. This may be due to the airway constriction that they experience when experiencing emphysema and acute asthma attack. As for the exercise, during heavy exercising, there is a greater need for ventilation, thus, it is compensated by increased respiratory rate and reduction in the expulsion of air from the body. In the inspiratory reserve volume, all of the patients had shown a lesser IRV compared to the normal patient. The lowest IRV was seen on patients who had undergone heavy exercise because there is a need for an increased respiratory rate so therefore, the amount of air remaining in the lungs will be reduced. The residual volume of the patients who had done exercise is comparably the same to that of the normal patient. That is, the amount of air that remains in the lungs after complete expiration would be the same for patients not experiencing pulmonary problems. On the contrary, in patients with acute asthma attack, it is greater, and more noticeably higher in patients with emphysema. This is due to the airway constriction in these patients that resists the flow of air from the lungs. Consequently, it is also in these patients who had lesser FVC and FEV 1 compared to normal, and is again due to same reasons. However, the RV of patients who used inhaler gradually decreased due to relief in clogged airway. The total lung capacity remained the same in all patients, that is, 6000 mL. This meant that all of the patients used and examined were males. In summary, it can be concluded that different breathing classification among patients have a varied values for their respiratory volumes and capacities that deviate

as compared to that of the normal patient. This is primarily due to obstructed passage of  air from the lungs due to airway constriction. And that, in cases like acute asthma attack, an inhaler can provide a relief for the airway. ACTIVITY 3: Effect of Surfactant and Intrapleural Pressure on Respiration

The objectives of this experiment include, first, is to understand the terms surfactant, surface tension, intrapleural space, intrapleural pressure, pneumothorax, and atelectasis. Second, is to understand the effect of surfactant on surface tension and lung function. And lastly, to understand how negative intrapleural pressure prevents collapse.  An important force that can be accounted during respiration is the surface tension. It is a tension produced by unequal attraction in a gas-liquid boundary. This force resists any force that tends to increase surface area of the gas-liquid boundary and acts to decrease the size of hollow spaces such as those in alveoli and microscopic air spaces. In lungs, there is a surfactant which is a detergent-like mixture of lipids and proteins that reduces the attraction between water molecules, thereby, decreasing surface tension. It is contained in the aqueous film covering the alveolar surfaces The negative intrapleural pressure is crucial in preventing the collapse of the airway. This pressure can be caused by two different forces dependently. First is by the tendency of the lung to recoil because of its elastic properties and the surface tension of  the alveolar fluid. Second, the tendency of the compressed chest wall to recoil and expand outward. The combined action of these force pull the lungs away from the thoracic wall resulting to a partial vacuum in the pleural cavity. Intrapleural space is lower than atmospheric pressure , hence, any opening generated in the pleural membranes equalizes the intrapleural pressure with atmospheric pressure resulting to a condition known as Pneumothorax. When this condition further results to a lung collapse, it is otherwise termed as atelectasis.

Results: Radius 5

Radius 5

Radius

Breath Rate 15

Surfactan t 0

Pressure Pressure Left Right -4 -4

Flow Left 49.69

Flow Right 49.69

Total Flow 99.38

Breath Rate 15

Surfactan t 2

Pressure Pressure Left Right -4 -4

Flow Left 69.56

Flow Right 69.56

Total Flow 139.13

Breath Rate

Surfactan t

Pressure Pressure Left Right

Flow Left

Flow Right

Total Flow

5

15

4

Radius

Breath Rate 15

Surfactan t 0

Breath Rate 15

Surfactan t 0

5

Radius 5

-4

-4

89.44

89.44

178.88

Pressure Pressure Left Right -4 -4

Flow Left 49.69

Flow Right 49.69

Total Flow 99.38

Pressure Pressure Left Right 0.00 -4

Flow Left 0.00

Flow Right 49.69

Total Flow 49.69

Radius 5

Radius 5

Breath Rate 15

Surfactan t 0

Pressure Pressure Left Right 0.00 -4

Flow Left 0.00

Flow Right 49.69

Total Flow 49.69

Breath Rate 15

Surfactan t 0

Pressure Pressure Left Right -4 -4

Flow Left 49.69

Flow Right 49.69

Total Flow 99.38

Table 4: Summary of results

Based on the results, it can be seen the effect of a surfactant on the maintenance of a negative intrapleural pressure. As the surfactant was applied to the lungs, the pressure on the left and right lung was maintained like that of the start of the exercise. Furthermore, it increased the flow rate on each lung, also the total flow as compared when the surfactant was absent. In summary, it can be concluded that pulmonary surfactant is not just important in preventing the collapse of the lungs as in the maintenance of negative intrapleural pressure, but also in enhancing the efficacy of each lung by increasing the flow of air.

Literatures Cited: Griff, Edwin, et al.(2012). Physio Ex (9.0) Laboratory Simulations in Physiology. Pearson Education, Inc.: San Fransisco Guyton, A. and Hall, J., (1994). Textbook of Medical Physiology. 9 Saunders Company: Pennsylvania.

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edition. W.B.