Posted: April 6th, 2015

SCH1143D Systems Physiology;

SCH1143D Systems Physiology;

– Clinical Case Study –
This assignment will demonstrate your knowledge and understanding of the respiratory system, how surfactants and intrapleural pressure affect respiration, and how this knowledge can be used for clinical applications.
To prepare for this assignment, please read the following in your textbook:
• Chapter 22: The Respiratory System Pay particular attention to the following sections:
• The Lungs and Pleurae
• Pressure Relationships in the Thoracic Cavity
• Pulmonary Ventilation: Inspiration and Expiration
• Physical Factors Influencing Pulmonary Ventilation
Surfactants and Respiration
The amount of air that flows into and out of the lungs in 1 minute is the pulmonary minute ventilation, which is calculated by multiplying the frequency of breathing by the volume of each breath (the tidal volume). Ventilation must be regulated at all times to maintain oxygen in arterial blood and carbon dioxide in venous blood at their normal levels, that is, at their normal partial pressures.
Oxygen and carbon dioxide diffuse down their partial pressure gradients, from high partial pressures to low partial pressures. Oxygen diffuses from the alveoli of the lungs into the blood, where it can dissolve in plasma and attach to haemoglobin, and then diffuses from the blood into the tissues. Carbon dioxide (produced by the metabolic reactions of the tissues) diffuses from the tissues into the blood and then diffuses from the blood into the alveoli for export from the body.
In this exercise you will investigate the basic mechanics and regulation of the respiratory system. The concepts you will explore with a simulated lung will help you understand the operation of the human respiratory system in better detail.
To identify the physiological effect of surfactant and intrapleural pressure on respiration, a simple experiment was devised (Figure 1) using:
• Simulated human lungs suspended in a glass bell jar
• Rubber diaphragm – used to seal the jar and change the volume, and thus, pressure in the jar
• Valve – allows intrapleural pressure in the left side of the bell jar to equalise with atmospheric pressure
• Surfactant – a mixture of lipids and peptides that mimics the surfactant found in human lungs
• Oscilloscope
Figure 1: Experimental Set-Up for Testing the Effect of Respiratory Surfactant
(Zao, P., Stabler, T., Smith, L., Lokuta, A., and Griff, E. (2013). PhysioEx9.1: Laboratory Simulations in Physiology. San Francisco:Pearson.)
As the diaphragm moves inferiorly, the volume in the bell jar increases and the pressure drops slightly, creating a partial vacuum in the bell jar. This partial vacuum causes air to be sucked into the tube at the top of the bell jar and then into the simulated lungs. As the diaphragm moves up, the decreasing volume and rising pressure within the bell jar forces air out of the lungs.
The surfactant reduces surface tension in the alveoli by adsorbing to the air-water interface, with their hydrophilic parts in the water and their hydrophobic parts facing towards the air.
The experiment is repeated at 15 breaths/min with the following conditions:
• Two drops of surfactant is applied
• Four drops of surfactant is applied
• Valve opened on the bell jar (no surfactant)
• Valve closed on the bell jar (no surfactant) These data are presented below.
Experimental Data
Figure 2: Control Data
(15 breaths/min)
Figure 4: Surfactant Data
(Four Drops)
Figure 6: Intrapleural Pressure
(Valve Closed)
Figure 3: Surfactant Data
(Two Drops)
Figure 5: Intrapleural Pressure
(Valve Open)
Figure 7: Re-Set Data
(15 breaths/min)
(Zao, P., Stabler, T., Smith, L., Lokuta, A., and Griff, E. (2013). PhysioEx9.1: Laboratory Simulations in Physiology. San Francisco:Pearson.)
Table 1: Data Recorded for Respiration (Baseline, Surfactant, Intrapleural Pressure)
AssignmentRequirements
Descriptive Title
This should be a statement relating to what the assignment is about
IntroductoryParagraph
This should provide background information on what respiratory surfactant is, its chemical structure, and how it affects surface tension of the alveoli. References are required.
Results Interpretation
This should explain the effect of surfactant on respiration and the effect of intrapleural pressure on respiration.
You must refer to Figures 2-7 and Table 1 to guide your explanation using specific data points as evidence for your discussion (copy and paste these figures into your assignment if you wish). References are not required.
Questions
References are required.
1. What effect does the addition of surfactant have on the airflow?
2. Why does surfactant affect airflow in this manner?
3. What effect did opening the valve have on the left lung?Why does this happen?
4. What emergency medical condition does opening the left valve simulate?
5. In the last part of this activity, the air was drawn out of the intrapleural space which returned the lung to its normal resting condition. What emergency procedure would be used to achieve this result if these were the lungs in a living person?
6. What do you think would happen when the valve is opened if the two lungs were in a single large cavity rather than separate cavities?
Conclusion
This should provide an overall summary outlining the clinical considerations associated with a compromised intrapleural pressure. References are required.
References
• A minimum of five references should be provided
• These need to be in APA format (in-text and end-text)
• Do not referenceWikipedia (only .gov, .edu, .org websites are acceptable)
Submission Information
Formatting
11 or 12 size font; double spaced;Word document
Word Count
Four pages
(Not including references and cover sheet)