1. Respiratory System
Mechanics
Group 6
Marcelino
Mayor
Moises
Olasiman
Ong

2. Respiratory System
• The respiratory system is situated in the thorax and is
comprises of the nose, mouth, throat, larynx, trachea,
bronchi and lungs.
• The function of the respiratory system is to facilitate
gaseous exchange to take place in the lungs and tissue
cells of the body.
Respiration – process of transferring oxygen to and
removing carbon dioxide from cells in the body
Ventilation - physical process of moving air into and out
of the lungs

3. Diaphragm - main muscle of breathing or ventilation
2 Phases of Ventilation:
a. Inspiration – air is taken into the lungs
- occurs as the external intercostal
muscles and the diaphragm contract.
b. Expiration – air is expelled out of the lungs
-inspiratory muscles relax, causing the
diaphragm to rise and the chest wall to
move inward.

4. Objectives
• To describe the role of muscles and volume changes in
the mechanics of breathing
• To understand that the lungs do not contain muscle and
that respirations are therefore caused by external forces
• To explore the effect of changing airway resistance on
breathing
• To study the effect of surfactant on lung function
• To examine the factors that cause lung collapse
• To understand the effects of hyperventilation,
rebreathing, and breath holding on the CO2 level in the
blood.

5. Methodology
• Use of the program Physio Ex 5.0
• 5 Activities were done.
• Activity 1: Measuring Respiratory Volumes
• Activity 2: Examining the Effect of Changing Airway
Resistance on Respiratory Volumes
• Activity 3: Examining the Effect of Surfactant
• Activity 4: Investigating Intrapleural Pressure
• Activity 5: Exploring Various Breathing Patterns

6. Figure 1. Opening Screen of the Respiratory Volumes
Experiment

7. Figure 2. Opening Screen of the Factors Affecting
Respirations Experiment

8. Figure 3. Opening screen of the Variations in Breathing
Experiment

9. Results and Discussion
Table 1. Baseline Respiratory Values
Pump
Radius Flow T.V. ERV IRV RV VC FEV1 TLC
Rate
5.00 13,356 500 1200 3091 1200 4791 3541 5991 15

10. Results and Discussion
• Minute Respiratory Volume (MRV)
- the volume of gas inhaled or exhaled from a
person's lungs in one minute
- can be calculated by multiplying tidal volume by
Breaths per minute (BPM)
• MRV = TV x BPM
= 7500 ml/min
• It is an important parameter in respiratory medicine due
to its relationship with blood carbon dioxide levels.

11. Results and Discussion
Table 2. Values of Airway resistance on Respiratory Volumes
Pump
Radius Flow TV ERV IRV RV VC FEV1 TLC
Rate
4.50 7.963 328 787 2,028 1,613 3,143 2,303 4,756 15
4.00 4,983 205 492 1,266 1,908 1,962 1,422 3,871 15
3.50 2,919 120 288 742 2,112 1,150 822 3,262 15
3.00 1,578 65 156 401 2,244 621 436 2,865 15

12. 2 types of Pulmonary Diseases
• Obstructive Pulmonary Disease
- characterized by chronic obstruction of the small
airways.
- people having obstructive pulmonary diseases
have difficulty in removing air from their lungs.
- ex. Bronchitis, Emphysema, and Asthma
• Restrictive Pulmonary Disease
- restrict lung expansion, resulting in a decreased
lung volume, an increased work of breathing, and
inadequate ventilation and/or oxygenation.
- ex. Pulmonary Fibrosis, Pneumonia, Pulmonary
Edema, or other types of inflammatory lung diseases.

13. Results and Discussion
Table 4. Comparison of a Normal and an Addition of Surfactant in the Lungs
Pump Surfact Pressur Pressur Flow Flow Total
Radius
Rate ant e left e right Left Right Flow
5 15 5 0.53 0.53 49.69 49.69 99.38
5 15 7 0.53 0.53 69.56 69.56 139.13

14. Results and Discussion
• Surface tension arises because water molecules are
more strongly attracted to one another than to air
molecules.
• Surface tension produces an inwardly directed force that
tends to reduce alveolar diameter.
• Pulmonary surfactant is a lipoprotein rich in
phospholipid.
• Surface tension arises because water molecules are
more strongly attracted to one another than to air
molecules.

15. Results and Discussion
Table 4. Investigating Intrapleural Pressure
Pump Surfact Pressur Pressur Flow Flow Total
Radius
Rate ant e left e Right Left Right Flow
5.0 15 5 0.53 0.53 49.69 49.69 99.38
5.0 15 5 0 0.53 0 49.69 49.69
5.0 15 5 0 0.53 0 49.69 49.69
5.0 15 5 0.53 0.53 49.69 49.69 99.38

16. Results and Discussion
• Intrapleural Pressure - pressure within the pleural cavity.
Less than the pressure within the alveoli.
• Negative pressure caused by 2 forces:
- tendency of the lung to recoil due to its elastic
properties
- surface tension of the alveolar fluid
• Opening in the thoracic wall causes equalization of the
intrapleural and atmospheric pressure (Pneumothorax)
• Pneumothorax allows lung collapse, a condition called
atelectasis.

17. Results and Discussion
Table 5. Pressure, Pump Rate and Total Flow
in Various Breathing Patterns
Max Pump
Condition PCO2 Min PCO2 Radius Total Flow
PCO2 Rate
Rapid
43.77 45.00 40.54 39.19 5.0 2,683.40
Breathing
Rebreathin
47.97 52.95 45.00 14.93 5.0 2,941.31
g
Breath
51.86 58.00 45.00 13.87 5.0 2,950.11
Holding

18. Conclusion
• The respiratory system is important in gas-exchange and
works through inspiration and expiration.
• There are factors affecting the ventilation of an organism
such as surface tension and diseases
• Rapid breathing causes a decrease in PCO2 and breath
holding causes an increase in PCO2