Question

ces of inspiration, ich the height and the diameter the diaphr do the thoracicavity directly by the as well as does the volume. As the As the inspiratory muscles relax, the lungo ral themes , they increase buch muscles and talent muscles. When the head phon the thoracica , which increases in wome. Recall that the lungs are anached to the pluralembranes. For this walans. F the lungs her and diameter i nd the int we in here within the all, the pumy pred rs. When sha hri , and the un b y the last record the Athens causes them to me to their original, smaller sire. This decreases the volum ere is a cheanhe monary pressure. When the intrapuna e re h er than the pheric pressure ure the event of food e n , veral acce munces of expiratiminde in s tal muscles will further decrease the height and diameter of the thoracic cavity, veral accessory muscles of expiration, including the Internal Procedure 1 Model Ventilation with the Bell Jar Model In this perdure we will use a bell.jar model of the lungs, shown in Figure 21.1 to view the effects of pressure and volume on ventilation. The hell-jar model has two balloons, each representing one lung, and a flexible membrane on the bottom that represents the diaphragm muscle. When you have completed the activity, answer Check Your Understanding questions 1 and 2 (p. 619) 1 Apply upward pressure to the membrane. This represents how the diaphragm le looks when it is relaxed. What has happened to the pressure of the system has it increased or decreased? What happened to the volume of the lungs? RGURE 23.3 Bell-jar modelet the lungs, simulated inspiration 2 Now slowly release the membrane. This represents the diaphragm muscle flattering out as it contracts. What is happening to the pressure as you release the membrane? What happened to the volume of the lungs? 3 If your bell-jar model has a rubber stopper in the top, you can use it to demonstrate the effects of a pneumothorax no mol-THOR-a) on lung tissue. A pneumothorax generally is caused by a tear in the pleural membranes that allows air to enter the pleural cavity. With the membrane flat and the lungs (halloons) inflated, loosen the rubber stoppet What happens to the lungs? Why? 610 Exploring Anatomy & Physiology in the Laboratory

Answer 1

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Q1: When the membrane is pushed upwards, pressure in the balloon increases and as a result, the volume of lungs decreases, thereby pushing the air out of the balloon.

Q2: When the membrane is released, pressure inside the balloon decreases and the volume increases, thereby letting the air into the balloon.

Q3: When the rubber stopper is loosened enough for the air from outside to enter the bottle, it results in the collapse of the balloon due to the force exerted by the air on the exterior of the balloon skin.

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This question requires the experimenter to record the actual results of the experiment, i.e., the values of respiratory volume with a spirometer.

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Q8

(a) Metabolic rate always increases during an exercises due to the need for breaking up of more Glucose molecules to provide energy. The waste products formed as a result of this glucose catabolism are carbon dioxide (CO₂), H⁺ ions and water.

(b) The waste products (CO₂ and H⁺ ions) affects the blood by lowering its pH due to the formation of carbonic acid.

(c) This change in pH leads to increase the rate of ventilation, so as to remove the excess CO₂ from the body.

(d) This question requires the experimenter to connect the above results to the values/observations of the experiment.