Surface Tension Pre-lab Answers

Pre-lab Quiz Results 1 Which of the following statements about surface tension is false? You correctly answered: Surface tension acts to increase the size of the alveoli within the lungs. 2 Which of the following statements about surfactant is false? You correctly answered: Surfactant works by increasing the attraction of water molecules to each other. 3 Just before an inspiration begins, the pressure within the intrapleural cavity You correctly answered: is less than the pressure within the alveoli. 4 The respiratory condition of pneumothorax refers to You correctly answered: any opening that equalizes the intrapleural pressure with the atmospheric pressure. 5 A pneumothorax can lead to You correctly answered: atelectasis. Experiment Results Predict Questions 1 Predict Question 1: What effect will adding more surfactant have on these lungs? Your answer: Airflows will further increase. 2 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: The lung will reinflate in one breath. Stop & Think Questions 1 Why did the sequential additions of surfactant change this lung system? You correctly answered: Surface tension was sequentially decreased. 2 Premature infants often have difficulty breathing because the amount of surfactant in their lungs is You correctly answered: too low. 3 What happened to the left side of the bell jar when the valve was opened? You correctly answered: The intrapleural pressure equalized with the atmospheric pressure. 4 Did the collapsed left lung reinflate? You correctly answered: No, it did not. Experiment Data Airway Radius (mm) Breath Rate (breath/min) Surfactant Pressure Left (atms) Pressure Right (atms) Flow Left (ml/min) Flow Total Right Flow (ml/min) (ml/min) 5 15 0 -4.00 -4.00 49.69 49.69 99.38 5 15 2 -4.00 -4.00 69.56 69.56 139.13 5 15 4 -4.00 -4.00 89.44 89.44 178.88 5 15 0 -4.00 -4.00 49.69 49.69 99.38 5 15 0 0.00 -4.00 0.00 49.69 49.69 5 15 0 0.00 -4.00 0.00 49.69 49.69 5 15 0 -4.00 -4.00 49.69 49.69 99.38 Post-lab Quiz Results You scored 100% by answering 4 out of 4 questions correctly. 1 The addition of surfactant to the lung interior You correctly answered: increased airflow. 2 Opening the valve in the side of the glass bell jar You correctly answered: simulated pneumothorax. 3 In this activity a pneumothorax is automatically followed by You correctly answered: atelectasis. 4 The best way to rapidly reinflate a person's collapsed lung is to You correctly answered: pump air out of the intrapleural space to recreate negative pressure. Review Sheet Results 1 What effect does the addition of surfactant have on the airflow? How well did the results compare with your prediction? Your answer: Surfactant is a compound that lowers surface tension by increasing its spreading and wetting properties. Therefore when the surfactant was added on the lungs it increased the airflow because the resistance was reduced within the lungs, This is what I predicted would happen. 2 Why does surfactant affect airflow in this manner? Your answer: Surfactant affects airflow in this manner because it decreases surface tension within the alveoli, this makes it easier for the alveoli to increase surface area for gas exchange thus making airflow easier in the lungs. 3 What effect did opening the valve have on the left lung? Why does this happen? Your answer: When I opened the valve on the left lung it stimulated the lung to collapse. This occurred because the intrapleural and atmospheric pressure equaled. Normally the intrapleural pressure is slightly less than the atmospheric pressure so when I opened the valve pneumothorax occurred. 4 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: When I reopened the the valve I expected the lung to re-inflate however, that did not happen. The lung didn't re-inflate because the intrapleural pressure was still less than the intrapulmonary pressure. 5 What emergency medical condition does opening the left valve simulate? Your answer: The emergency medical condition that occurred when opening the left valve stimulated pneumothorax which is the collapsing of the lung. 6 In the last part of this activity, you selected 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: The emergency procedure that would be used to re-inflate the lung in a living person would be aspiration with a needle, using a chest tube, or surgery. these procedures allow air back into the lung to get the pressure in the intrapleural cavity slightly below the atmospheric pressure again. 7 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: If the valve was opened with the two lungs in one single cavity then both lungs would collapse, and the person wouldn't be able to breath, most likely leading to death.