Study Questions Lab 6 Pulmonary Fxn

Question 1

1. What is the standard barometric pressure at sea lvl? At SFU?

Answer 1

1. 760 mmHg

2. 730 mmHg

Question 2

2. What is the % of O2 in air at sea level? At SFU?

Answer 2

1. 20.93%

2. 20.93%

Question 3

3. What does the ambient in ATPS refer to?

Answer 3

the temp at the time a respiratory gas volume measured

Question 4

4. When do we express a gas volume in Standard Temperature Pressure Dry (STPD)?

Answer 4

Whenever want to know AMT OR # of GAS MOLECULES

• i.e. when calculating the amount O2 consumed and amount CO2 produced

Question 5

5. When do we express a gas volume in BTPS (Body Temperature Pressure Saturated)

Answer 5

Want to know VOLUME OF GAS VENTILATED BY LUNGs

Question 6

6. For “water in contact w/its own vapour” in a sealed system (such as when a subject expires into a balloon), what is the RH?

Answer 6

100%

Question 7

7. If a subject’s expired gas is collected at SFU, will the STPD value for a gas volume be higher, lower, or the same as the ATPS value? How will the BTPS value compare w/ATPS value?

Answer 7

• ATPS to STPD would be lower
  aka STPD lower than ATPS
  STPD correction factor @ SFU = 0.850-0.900
• ATPS to BTPS would be higher
  aka BTPS higher than ATPS
  BTPS correction factor @ SFU = 1.05-1.10

Question 8

8. What standard values are used for the following:
   - resting body core temp
   - vapour pressure in lung

Answer 8

• 37 d C

- 47 mmHg

Question 9

9. Define, give units for, explain, and be able to indicate on a chart recording the following terms:
10. VE
11. TLC
12. VT
13. RV
14. VC
15. MBC = MVV
16. IC
17. FVC
18. ERV
19. FEV1.0
20. FRC
21. MMFR
22. RV

Answer 9

1. Minute ventilation (VE) = the volume of either inspired OR expired air (but not both) in one minute ( TV 500ml x Breathing frequency 12-16 breaths) 6 - 8 liters/min at rest
2. Total lung capacity = the volume of air that is held in lungs at the end of a maximal inspiration
   IC + ERV + RV
3. Tidal volume (VT) is the volume of gas inspired or expired with each breath at rest or during any stated activity. (~500ml)
4. Residual volume (RV) = volume of gas remaining in the lungs after forced expiration.
5. Vital capacity (VC) = greatest volume of gas that can be expelled by voluntary effort after maximal inspiration.
   - is the sum of the inspiratory capacity and the expiratory reserve volume.
6. Maximum breathing capacity (MBC): l/min
   - the max volume of expired gas in a given time period during max effort
7. Inspiratory capacity (IC)
   - volume of air that can be maximal inspired at the end of a normal expiration
8. Forced vital capacity (FVC): ml
   - following max inspiration: expire maximally as hard and as fast as possible; objective: to expire entire VC as rapidly as possible
9. Expiratory reserve volume (ERV) = maximal volume that can be exhaled from the resting end-expiratory position.
10. Forced expiratory volume in 1.0 second (FEV1.0): ml
    - volume air expired during first one second of forced vital capacity maneuver
11. Functional residual capacity (FRC): ml
    - volume gas remaining in lungs at end of quiet exhalation
    - FRC = ERV + RV
12. Maximal Mid-expiratory flow rate (MMFR): l/sec
    - max flow rate of air achieved over the middle 50% of FVC maneuver
    - AKA “FEF 25-75%”: forced expiratory flow rate from 25-75% FVC maneuver

Question 10

10. Compare and contrast obstructive and restrictive pulmonary disorders and give examples of each

Answer 10

Obstructive:

• BLOCKAGE or NARROWING of airways causing INC AIRWAY RESISTANCE
• bronchiolar obstruction can result from inflammation and edema
• asthma, bronchitis are obstructive disorders
• MMFR, FEV1, peal expiratory FR, MVV are all dec, and FEV1/FVC ratio less than 70%
• air trapping inc FRC, RV, and TLC

Restrictive:

• airways ok but damage to LUNG TISSUE resulting in DEC ELASTICITY and DEC COMPLIANCE = hard to expand lung
• pulmonary fibrosis and pneumonia are restrictive disorders
• a lung volumes reduced (slow VC, FVC, RV, FRC, TLC) cause lung tissue stiff and can’t expand
• MBC, peak expiratory flow rate, FEV1, MMFR are reduced
• FEV1/FVC ratio higher than 90%

Question 11

11. How should subject be positioned when performing pulmonary fxn measurements

Answer 11

seated in an

upright position.

Question 12

12. Is it possible for subject to have VC w/in normal range but value for FEV1.0 below normal range? Why or why not?

Answer 12

• Yes in obstructive disorders where airways collapse during expiration before a normal amt of air emptied from lung
• Airways have increased resistance so they will have compromised expiration thus less than 70 % of the FVC may be expelled in the first 1 second of the FVC maneuver. BUT they can still expand their lung tissue so they may have a relatively normal VC.

Question 13

13. Why does maximal voluntary ventilation dec w/age

Answer 13

Lung capacity dec with age as compliance dec with age (similar to restrictive disorders, hard to expand lungs)
- the amount of elastin within their lungs decreases and the amount of collagen increases

Question 14

14. What effect would u expect smoking to have on FEV1.0 and MVV

Answer 14

Smoking will cause obstructive disorder so FEV1.0 and MVV will both dec

Question 15

15. In pulmonary fxn testing what does “normal” mean

Answer 15

It is the mean of values derived from a large group of heathy people of the same age, sex, height, and race. Note there is btwn-subject variability within that “normal” population

Question 16

16. In ex 2 the RSA prominence is the diff btwn HR b4 and after inhalation. What is the avg RSA prominence of subject?

Answer 16

13.95 bpm

Question 17

17. In breath-holding experiments , we don’t actually measure PaO2. We measure another variable and assume it equals PaO2. Whats other variable

Answer 17

FAO2 is being measured after the breath-hold experiment, we assume that multiplying this by barometric pressure equals PAO2.

Question 18

18. Why can’t person hold breath long enough to hurt herself

Answer 18

As CO2 accumulates and pH decreases, these are the most potent stimulants of the
respiratory centers in the brain to stimulate breathing and override voluntary
inhibition. Depleted O2 as well.

Question 19

19. What stimulates breathing? Which of these stimuli are strongest? Weakest? Where are the sensors located?

Answer 19

1) Chemoreceptors that sense changes in partial pressures (arterial blood) of O2 and CO2 and in pH provide input to the respiratory control
centers in the brain.
2) Among these, an inc in CO2 and dec in pH are the strongest stimulants for breathing.
3) PO2 is the weaker stimulant for breathing.
4) Peripheral chemoreceptors are in the aortic and carotid bodies. Central chemoreceptors are in the medulla.

Question 20

20. What are the expected breath-hold time, and PAO2, and PACO2 at “break point” for breath holding after each of the following conditions
21. at end of normal inspiration
22. after deep inspiration
23. after deep inspiration of O2
24. after hyperventilation and a deep inspiration
    Explain these expected results in physiological terms

Answer 20

1. 30 sec
   - PACO2 = 45-55 mmHg; PAO2 = 60-70 mmHg
2. 60 sec
   - PACO2 = 48-55 mmHg; PAO2 = 65-70 mmHg
3. 90 sec.
   - PAO2 will be higher than normal room air PIO2 of 150 mmHg
   - PACO2 will increase to 50-55 mmHg
4. 2 mins.
   - PO2 < 50mmg
   - PCO2 40-55mmHg

Question 21

21. Why does hyperventilation produce light-headedness? How would placing paper bag over mouth and breathing in and out reduce this effect?

Answer 21

Hyperventilation produces light-headedness because it causes hypobaric conditions that reduce blood flow to the brain. Placing a bag over the mouth helps to recycle expired CO2 and keep levels higher.

Question 22

22. A proportional reduction of all lung volumes (VC, FRC, RV, and TLC) is consistent w/:
    a. restriction
    b. obstruction
    c. combined restriction and obstruction

Answer 22

a. Restriction

Question 23

23. A subject that has TLC that is 110% of expected value, and RV/TLC ratio of 50%. This is consistent w:
    a. restrictive process
    b. obstructive process
    c. normal lung volume proportions

Answer 23

b. obstructive

Question 24

24. Explain how and why lung fxn changes w/ageing from age 25 onwards

Answer 24

With aging from 25 years onwards, lung compliance and elasticity decreases,
producing symptoms resembling restrictive disorders. This means FRC, VC, RV, and TLC will dec. FEV1.0 and MBC dec, but FEV1/VC will inc.