In this lab, you'll explore respiratory physiology. First you'll learn about spirometry and the clinically useful lung volumes and capacities. Then you'll do an activity that demonstrates the role of

2:24 min) Lu ng F u ncti on T e st (S pir o m etr y) (h ttp s:/ / w ww.y o utu b e.c o m /w atc h ?v =G r0Z xo Z R5 8Y ) (h ttp s:/ / w ww.y o utu b e.c o m /w atc h ?v =G r0Z xo Z R5 8Y ) Video Credit: National Jewish Health (h ttp s://w ww.y o utu be.c o m /c h an nel/U ChW LR XR ic 72g _lJ 9Y SrIT M A) As you can see from figure 1, there are a number of dif ferent lung volumes and capacities that are useful to measure, but we're going to focus tidal volume (TV), vital capacity (VC), and the forced expiratory volume in one second (FEV ). 1 7/15/2020 Activity 1: Spirometery and Lung Volumes & Capacities: Sum20 PYSO 001 #50663 HUMAN PHYSIOLOGY -Online https://canvas.pasadena.edu/courses/1105733/pages/activity-1-spirometery-and-lung-volumes-and-capacities?module_item_id=12086014 2/4 Figure 1: Lung volumes and capacities. Im age C re dit : F ig ure 22.1 8 (https://openstax.org/books/anatomy-and- physiology/pages/22-3-the-process-of-breathing#fig-ch23_03_04) R esp ir a to ry V o lu m es a n d C ap acit ie s (https://openstax.org/books/anatomy-and-physiology/pages/22-3-the-process-of-breathing#fig-ch23_03_04) fr o m O penS ta x A nato m y a nd P hysio lo gy.

Normally , you breathe in and out without giving it much thought. Like the tides coming in and going out with regularity , the change in volume in your lungs while breathing is your tidal volume. Tidal volume (TV), which is the volume of air that you inhale or exhale with normal quiet breathing , is about 500 ml for the average adult male.

V ital capacity (VC) is a reliable diagnostic indicator of one’ s pulmonary status. Vital capacity (VC) varies with age, gender , body size, and with other factors such as physical fitness and lifestyle (smoking). To maintain normal homeostasis, a person’ s vital capacity should be at least 80% of the predicted value. The predicted value varies among individuals and is influenced by biological sex, height, and age. In healthy young men, the maximum air that the lungs can hold is usually around 5.5 liters. In healthy young women, the maximum is normally about 4.0 liters. A greater than normal vital capacit y (>100% predicted) is common for singers and athletes such as swimmers, but also in patients with emphysema. In the case of emphysema, damage to the alveoli can lead to more space in the lungs, but that space is "dead space." A lower than normal vital capacity (< 80% predicted) is associated with smoking and restrictive pulmonary disorder , such as pulmonary fibrosis, respiratory muscle weakness, and obesity . In these restrictive pulmonary disorders, the lungs are not able to inflate as much as possible. For instance, with pulmonary fibrosis, fibrotic scar tissue takes up space that air would normally occupy , so the lungs cannot inflate to capacity. With obesity, extra weight impairs the ability of the lungs to expand to capacity .

Another important diagnostic value is the forced expiratory volume in 1 second (FEV ). FEV is the volume of air that can be forcibly exhaled in the first second of a forced vital capacity test. The 1 1 7/15/2020 Activity 1: Spirometery and Lung Volumes & Capacities: Sum20 PYSO 001 #50663 HUMAN PHYSIOLOGY -Online https://canvas.pasadena.edu/courses/1105733/pages/activity-1-spirometery-and-lung-volumes-and-capacities?module_item_id=12086014 3/4 %FEV1 represents the percentage of the total vital capacity that is exhaled in the first second of a forced vital capacity test. It is calculated using this formula: % FEV = (FEV /VC) x 100 %FEV is provides information about airflow and is useful for diagnosing obstructive pulmonary disorders . If your bronchioles became inflamed, constricted, or occluded due to mucous, the radius of your airways would be smaller than normal, increasing resistance to airflow and causing you to take longer to forcibly exhale during a vital capacity test. With obstructive pulmonary disorders, such as asthma, chronic bronchitis, and COPD, %FEV is lower than normal (<80%) due to the reduced radius of the airways. Patients with emphysema also tend to have a lower than normal %FEV due to the lack of elasticity of the lungs.

Let's take a look at some sample data and calculations. This is the data from a healthy 18 year old male athlete who is 6'3''. Based on his biological sex, gender and height, his predicted vital capacity is 4.8 L.

Below is the spirogram obtained from a lung function test. The upward slopes show when he was inhaling and the downward slopes show when he was exhaling.

Figure 2 . Spirogram for a healthy individual. Calc u la tin g Ac tu al Vi ta l C ap acit y First let's calculate his actual vital capacity . We can see that his maximum inhalation is 5.5 L, and his maximum exhalation was at 0.5 L. Thus, his actual vital capacity is 5.5 L - 0.5 L = 5.0. Calc u la tin g % P re dict ed 1 1 1 1 1 7/15/2020 Activity 1: Spirometery and Lung Volumes & Capacities: Sum20 PYSO 001 #50663 HUMAN PHYSIOLOGY -Online https://canvas.pasadena.edu/courses/1105733/pages/activity-1-spirometery-and-lung-volumes-and-capacities?module_item_id=12086014 4/4 To calculate his % predicted, we use the following formula: % predicted = (actual value/predicted value) x 100 His actual VC was 5.0 L, and his predicted VC was 4.8 L. That means that his % predicted was (5.0 L/4.8L) x 100 = 104% C alc u la tin g F E V a n d % FE V To calculate FEV , we need to determine the volume that he exhaled in the first second of his vital capacity test. W e see that the line intersects at about 1.5 L. This means that his FEV1 is 5.5 L -1.5 L = 4.0 L. Using the formula for % FEV1, we would get (4.0 L /5.0 L) x 100 = 80%. This would suggest that he has healthy lungs.

Dire ctio ns Now it's you're turn! Use the spirogram below to determine the patient's vital capacity and FEV . Note that the volume is in milliliters (ml) rather than liters for this spirogram.

Figure 3. Sample spirogram to analyze for the worksheet. Note that the volumes are in milliliters (ml).

Record your findings on the worksheet, and answer the other Activity 1 questions before moving on to Activity 2. 1 1 1 1