[PhysioEX Chapter 7 exercise 3] PEX-07-03

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Exercise 7: Respiratory System Mechanics: Activity 3: Effect of Surfactant and Intrapleural Pressure on Respiration Lab
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Pre-lab Quiz Results
You scored 100% by answering 5 out of 5 questions correctly.

Which of the following statements about surface tension is false?
You correctly answered: c. Surface tension acts to increase the size of the alveoli within the lungs.
Which of the following statements about surfactant is false?
You correctly answered: d. Surfactant works by increasing the attraction of water molecules to each other.
Just before an inspiration begins, the pressure within the intrapleural cavity
You correctly answered: b. is less than the pressure within the alveoli.
The respiratory condition of pneumothorax refers to
You correctly answered: c. any opening that equalizes the intrapleural pressure with the atmospheric pressure.
A pneumothorax can lead to
You correctly answered: b. atelectasis.

Experiment Results
Predict Question:

Predict Question 1: What effect will adding more surfactant have on these lungs?
Your answer : b. Airflows will further increase.

Predict Question 2: What will happen to the collapsed lung in the left side of the glass bell jar if you close the valve?
Your answer : c. The lung will remain collapsed.

Stop & Think Questions:
Why did the sequential additions of surfactant change this lung system?
You correctly answered: a. Surface tension was sequentially decreased.

Premature infants often have difficulty breathing because the amount of surfactant in their lungs is
You correctly answered: b. too low.

What happened to the left side of the bell jar when the valve was opened?
You correctly answered: b. The intrapleural pressure equalized with the atmospheric pressure.

Did the collapsed left lung reinflate?
You correctly answered: b. No, it did not.

Experiment Data:
Radius Breath Rate Surfactant Pressure Left Pressure Right Flow Left Flow Right Total Flow
5 15 0 -4 -4 49.69 49.69 99.38
5 15 2 -4 -4 69.56 69.56 139.13
5 15 4 -4 -4 89.44 89.44 178.88
5 15 0 -4 -4 49.69 49.69 99.38
5 15 0 0.00 -4 0.00 49.69 49.69
5 15 0 0.00 -4 0.00 49.69 49.69
5 15 0 -4 -4 49.69 49.69 99.38

Post-lab Quiz Results
You scored 100% by answering 4 out of 4 questions correctly.

The addition of surfactant to the lung interior
You correctly answered: c. increased airflow.
Opening the valve in the side of the glass bell jar
You correctly answered: d. simulated pneumothorax.
In this activity a pneumothorax is automatically followed by
You correctly answered: b. atelectasis.
The best way to rapidly reinflate a person's collapsed lung is to
You correctly answered: a. pump air out of the intrapleural space to recreate negative pressure.

Review Sheet Results

What effect does the addition of surfactant have on the airflow? How well did the results compare with your prediction?
Your answer:
Airflows incresead as predicted.
Why does surfactant affect airflow in this manner?
Your answer:
Because surfactant reduces the resistance and increase gas exchange surface.
What effect did opening the valve have on the left lung? Why does this happen?
Your answer:
The left lungs lose its fuction, because the pressure of intrapleural space and of intrapulmonary are equal, so the pressure
of atmosphere and of intrapulmonary are same so that air could not go to the left lungs.
What effect on the collapsed lung in the left side of the glass bell jar did you observe when you closed the valve? How
well did the results compare with your prediction?
Your answer:
The lung remained collapse, as predicted. because pressure difference with intrapleural space and lung did not established.
What emergency medical condition does opening the left valve simulate?
Your answer:
When there is no negative pressure in intrapleural space, lung could not do its function that get air in.
In the last part of this activity, you clicked the Reset button to draw the air out of the intrapleural space and return 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?
Your answer:
Take air out of intrapleural space, for example by using tube.
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?
Your answer:
In case that lungs divided with 2 cavity, when one of the cavities got wrong, the other one do its function. But In case that
lungs make just single large cavity, when there is some accident with intrapleural space, there is no replacement to breathe.