Lab 14 - Respiratory Physiology

Question 1

What is tidal volume (VT):

Answer 1

The volume breathed in each minute

- Normal breath

Question 2

What is Expiratory Reserve Volume (ERV)

Answer 2

The maximal amount of air that can be exhaled from the lungs after a normal expiration.
- Amount of air that can be expired forcibly beyond the tidal volume

Question 3

What is residual volume (RV)

Answer 3

The volume of gas left in the respiratory system after exhaling maximally.
- Air that cannot be expelled

Question 4

What is Vital Capacity (VC):

Answer 4

Measure of the maximum volume of gas in the respiratory system that can be exchanged with each breath.
- Biggest possible breath

Question 5

What is Total Lung Capacity ( TLC)

Answer 5

Measure of the volume of gas in the respiratory system at the end of a maximal inspiration.

Question 6

What is major difference between volume and capacity in the respiratory system

Answer 6

A capacity is the sum of at least two volumes.

Question 7

What is Forced Expired Volume ( FEV1)

Answer 7

Provides a measure of the resistance of the airways to flow.

Question 8

What happens during normal resting respiration in the same breath

Answer 8

The volume of the exhaled gas exceeds that of the inhaled gas.

Question 9

What is spirometry used for

Answer 9

Recording respiratory variables

Question 10

Where does gas exchange between air and blood occur

Answer 10

In the alveolar air sacs

Question 11

What is the efficiency of gas exchange dependent on

Answer 11

Ventilation; cyclical breathing movements alternately inflate and deflate the alveolar air sacs

Question 12

What does inspiration do

Answer 12

Provides the alveoli with some fresh atmospheric ai

Question 13

What does expiration do

Answer 13

Removes some of the stale air, which has reduced oxygen and increased carbon dioxide concentrations.

Question 14

Why is spirometry becoming more important

Answer 14

• As respiratory dieseases are increasing world wide
• Spirometry is the method of choice for a fast and reliable screening of patients suspected of having Chronic Obstructive Pulmonary Disease (COPD).

Question 15

What is COPD

Answer 15

• The 12th leading cause of death worldwide and the 5th leading cause in Western countries.
• Studies suggest COPD could climb to be the 3rd leading killer by 2020.
• Most COPD cases are completely avoidable; 85-90% of cases are caused by tobacco smoking.

Question 16

How can important aspects of lung function be determined

Answer 16

By measuring airflow and the corresponding changes in lung volume

Question 17

How was airflow measured in the past

Answer 17

By breathing into a bell spirometer, in which the level of a floating bell tank gave a measure of changes in lung volume. Flow, F, was then calculated from the slope (rate of change) of the volume, V:

Question 18

What is the more convenient way too measure airflow

Answer 18

Directly with a pneumotachometer - breath speed measuring device

Question 19

What was used in the lab

Answer 19

• Flow head - ‘ Lilly ‘ type that measures the difference in pressure either side of a mesh membrane with known resistance
• This resistance gives rise to a small pressure difference proportional to flow rate
• Two small plastic tubes transmit this pressure difference to the Spirometer Pod, where a transducer converts the pressure signal into a changing voltage
• The volume, V, is then calculated as the integral of flow:

Question 20

What is a complication in the volume measurement caused by

Answer 20

The difference in air temperature between the Spirometer Pod (at ambient temperature) and the air exhaled from the lungs (at body temperature).

Question 21

What does respiration consist of

Answer 21

• Repeated cycles of inspiration followed by expiration.
• During the respiratory cycle, a specific volume of air is drawn into and then expired from the lungs; this volume is the Tidal Volume (VT)

Question 22

What happens in normal ventilation

Answer 22

The breathing frequency (ƒ) is approximately 15 respiratory cycles per minute.

Question 23

How does breathing frequency vary

Answer 23

With the level of activity

Question 24

What is the Expired Minute Volume ( VE)

Answer 24

• The product of ƒ and VT
• The amount of air exhaled in one minute of breathing.
• Also changes according to level of activity

Question 25

What is residual volume ( RV)

Answer 25

The volume of air remaining in the lungs after a full expiration, residual

Question 26

Why cant residual volume be measured by spirometry

Answer 26

A volunteer is unable to exhale any further (lungs may stick together!).

Question 27

Terms and units

Answer 27

- Respiratory Rate -breaths / min (BPM) - Expired Minute Volume - L/min - Tidal Volume - L - Inspiratory Reserve Volume - L - Expiratory Reserve Volume - L -Residual Volume- L - Inspiratory Capacity - L - Expiratory Capacity - L - Vital Capacity - L - Functional Residual Capacity - L Total Lung Capacity - L - Peak Inspiratory Flow - L/min - Peak Expiratory Flow - L/min - Forced Vital Capacity - L Forced Expired Volume in one second- L

Question 28

What is inspiratory reserve volume

Answer 28

Amount of air that can be inspired forcibly beyond the tidal volume

Question 29

Comment on the differences between the experimental and predicted values for VC, FRC and TLC in the table above. What could cause these differences, if any

Answer 29

VC, FRC and TLC values are higher than experimental Differences are due to individual varitation. Predicted values are based on large scale population studies and are averages. If the experimental values are consistenly lower than the predicted it may be due to poor tecnique on behalf of the volunteer i.e. insufficient inspiratory and/or expiratory effort

Question 30

In quiet breathing, muscular effort is used mainly in inspiration, and expiration is largely passive, due to elastic recoil of the lung. Can you relate this fact to the pattern of expiratory and inspiratory flow?

Answer 30

Normal pattern of breathing is efficient that it requires muscular effort for only a short time - Inspiration is shorter to make it more efficient as it requires muscular effort - Normal pattern of inspiration and expiration should shows a quiet period prior to each inspiration. Muscles must contract before inspiration can begin. - There is a latency associated with this contraction

Question 31

Why RV cannot be determined by ordinary spirometry

Answer 31

You never fully exhale the gas you have, RV is the amount of gas inside your body remaining - Its the volume of air that remains in the lungs after a full expiration

Question 32

Describe the physiological significance of the FEV1/FVC ratio?

Answer 32

Shows how much resistance there is of the airways to flow Indication of airways diameter. The higher this value, the faster air can flow through the airway so the lower the resistance and the wider the airway.

Question 33

Were your results for forced breathing consistent across all three trials? If not, why not?

Answer 33

It wasnt consistent but showed similar trends, inhaled different amounts = the amount exhaled was different AND measuring same person - lung capacity should not change in a person during measurement period

Question 34

Physiological events that occurred during this simulated asthma attack.

Answer 34

Harder to breathe in, more muscle force needed Diameter of airways shrink due to swelling and inflammation. This decrease in diameter gives a sensation of extreme difficulty in inhalation and exhalation. Physical activity becomes difficult because of this obstruction

Question 35

What factors contribute to differences in pulmonary parameters between the volunteers

Answer 35

Age, sex, body size and health condition

Question 36

What values have been affected by stimulated airway obstruction and why

Answer 36

An obstructed ( narrowed ) airway is unable to inhale or exhale as fast as those with normal diameter, due to increased resistance to flow. The total volume able to flow should be the same ( FVC unchanged ) but the rate at which air flows is slower leading to a lower ration.