3.1.1e Spirometry & Lung Function

Question 1

What factors cause the amount of gas exchange needed in your lungs to vary

Answer 1

Vary depending on your size and level of activity.

The gaseous exchange system must be able to respond to the differing demands of your body

Question 2

3 different ways to measure the volume of air drawn in & out of the lungs

Answer 2

• A peak flow meter
• Vitalographs
• Spirometer

Question 3

How can a peak flow meter be used to measure the volume of air drawn in & out of the lungs

Answer 3

A simple device that measures the rate at which air can be expelled from the lungs. Ppl who have asthma often use these to monitor how well their lungs are working

Question 4

How can Vitalographs be used to measure the volume of air drawn in & out of the lungs

Answer 4

More sophisticated versions of the peak flow meter. The patient being tested breathes out as quickly as they can through a mouthpiece, and the instrument produces a graph of the amount of air they breath out & how quickly it is breathed out - This volume of air is called the forced expiratory volume in 1 second

Question 5

How can a spirometer be used to measure the volume of air drawn in & out of the lungs

Answer 5

Commonly used to measure different aspects of the lung volume, or to investigate breathing patterns. Can be used to measure the volume of gas breathed in & out under diff conditions. There are many different forms of the spirometer but they all use the basic principles (shown in dia in ss)

Question 6

see diagram of a spirometer in images

Question 7

Different aspects of the lung volume that can be measured

Answer 7

• Tidal volume
• Vital capacity
• Inspiratory reserve volume
• Expiratory reserve volume
• Residual volume
• Total lung capacity

Question 8

Components of lung volume: Tidal volume

Answer 8

Volume of air that moves into & out of the lungs during a normal breath

(Usually about 0.4dm^3)

Question 9

Components of lung volume: Vital capacity

Answer 9

The maximum volume of air that can be breathed during a forced breath in & then out

Question 10

Components of lung volume: Inspiratory reserve volume

Answer 10

The maximum volume of air (in excess of the tidal volume) we can breathe IN during one forced breath

Question 11

Components for lung volume: Expiratory reserve volume

Answer 11

The maximum volume (in excess of the tidal volume) we can breathe OUT in one forced breath

Question 12

Components of lung volume: Residual volume

Answer 12

The amount of air left in the lungs after a forced breath out. You cannot measure this using a spirometer

Question 13

Components of lung volume: Total lung capacity

Answer 13

The sum of the Vital capacity and the Residual volume

Question 14

see diagram of recordings from spirometer on Goodnotes

Answer 14

Only need to know vital capacity, tidal volume, breathing rate & oxygen uptake

Question 15

How does the pattern & volume of breathing change

Answer 15

As the demands of the body changes

Question 16

What is breathing rate

Answer 16

The number of breaths taken per minute

Question 17

What is ventilation rate

Answer 17

The total volume of air inhaled in one minute

Question 18

Equation for calculating ventilation rate

Answer 18

Ventilation rate = Tidal volume x Breathing rate (per min)

Question 19

dm^3 –> cm^3

Answer 19

x1000

Question 20

What is ventilation rate measured in

Answer 20

dm^3

Question 21

What is Tidal volume measured in

Answer 21

dm^3

Question 22

What is breathing rate measured in

Answer 22

Breaths per minutes

Question 23

What happens to the tidal volume when oxygen demands of the body increases (eg during exercise)

Answer 23

The tidal volume of air moved in & out of the lungs with each breath can increase from 15% to as much as 50% of the vital capacity

Question 24

What happens to the breathing rate when oxygen demands of the body increase (eg during exercise)

Answer 24

The breathing rate increases

Question 25

WHY does the tidal volume and breathing rate increase when oxygen demands of the body increase (eg during exercise)

Answer 25

This way, the ventilation of the lungs and therefore the oxygen uptake during gaseous exchange can be increased to meet the demands of the tissues

Question 26

What is spirometry

Answer 26

Spirometry is a pulmonary function (PFT). It is used to measure 2 things relating to inhalation & exhalation of air: - **volume** (how much air a person can hold in their lungs) - **speed** (flow rate at which ppl can do this)

Question 27

Why are spirometers used

Answer 27

For assessing conditions such as asthma, pulmonary fibrosis, chronic pulmonary obstructive disorders (CPOD) Also used in sport science testing as an indicator of lung function

Question 28

What can a spirometer give readings of

Answer 28

- Tidal volume - Vital capacity - Breathing rate - Oxygen uptake

Question 29

How do spirometers work

Answer 29

1. A spirometer has an **oxygen-filled** chamber w a **moveable lid** 2. The person breathes through a **tube** connected to the oxygen chamber 3. As the person breathes in & out, the lid of the chamber moves **up & down** 4. These movements can be recorded by a **pen** attached to the lid of the chamber - this writes on a **rotating drum**, creating a **spirometer trace**. OR the spirometer can be hooked up to a **motion sensor** - this will use the movements to produce **electronic signals**, which are picked up by a **data logger** 5. The **soda lime** in the tube the subject breathes into absorbs **CO2**

Question 30

What is **Oxygen consumption** OR **Oxygen uptake**

Answer 30

The rate at which an organism **uses up** oxygen

Question 31

SEE PG75 FOR DIA OF SPIROMETER

Question 32

Why does the total volume of gas in the chamber decrease overtime in spirometer

Answer 32

- The air that's breathed out is a **mixture of oxygen & CO2**. - The CO2 is absorbed by the **soda lime** - so there **only oxygen** in the chamber which the subject inhales from. - As this oxygen gets **used up** by respiration, the **total volume decreases**

Question 33

MUST SEE PG75 ANALYSING GRAPH TO WORK OUT BREATHING RATE, TIDAL VOL, VITAL CAPACITY, OXYGEN CONSUMPTION

Question 34

How to calculate **breathing rate** from a graph

Answer 34

Count how many 'peaks' there are within 1 minute (_ breaths per minute)

Question 35

How to calculate **tidal volume** from a graph

Answer 35

Find distance between peak & bottom of the trace (_dm^3)

Question 36

How to calculate **vital capacity** from a graph

Answer 36

Find distance between the maximum (biggest) peak & the lowest point in the trace

Question 37

How to calculate **oxygen consumption** from a graph

Answer 37

This is the **decrease in the volume of gas** in the spirometer **chamber** Take the average slope of the trace (_dm^3/min)