4.6.3
Measuring Gas Exchange
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Measuring Lung Function
The function of the lungs can be measured using a spirometer. Measuring gas exchange allows doctors to identify problems in the lungs.

Spirometer
- A spirometer is a piece of apparatus that measures the gas exchange in the lungs.
- A spirometer measures the volume of air that is inspired and expired by an individual.
- An individual breathes into and out of a spirometer to measure the lung function.
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Tidal volume & vital capacity
- A spirometer can measure the tidal volume.
- Tidal volume is the volume of air in a normal breath (at rest).
- The average tidal volume is about 0.4 dm3 − 0.5 dm3.
- A spirometer can measure vital capacity.
- Vital capacity is the maximum volume of air that can be breathed in and out of the lungs.
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Ventilation rate
- A spirometer can measure the ventilation rate.
- The ventilation rate is the number of breaths a person takes per minute (at rest).
- The average ventilation rate is about 15 breaths per minute.
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Forced expiratory volume
- A spirometer can measure forced expiratory volume.
- Forced expiratory volume is the maximum volume an individual can expire in one second.
- The forced expiratory volume cannot be more than the total volume of gas in the lungs.
- This is because there is always a small amount of air that cannot be expired (the residual air). The residual air ensures the alveoli do not close.

Pulmonary ventilation rate (PVR)
- Pulmonary ventilation rate can be calculated using the equation:
- PVR = tidal volume × breathing rate
- If you are given two of these values, the equation can be rearranged to calculate the third value.

Exercise
- During exercise, the following can be seen on the spirometer trace:
- Increased tidal volume.
- Increased ventilation rate.
- Constant vital capacity.
- The tidal volume and ventilation rate increase during exercise as more oxygen is required for respiration.
- Respiration provides the energy required for exercise (e.g. for increased muscle contraction).
1Principles of Science I
1.1Structure & Bonding
1.1.1Atomic Model1.1.2Electron Shells, Sub-Shells & Orbitals1.1.3Ionic Bonding1.1.4Representing Ionic Bonds1.1.5Covalent Bonding1.1.6Representing Covalent Bonds1.1.7Metallic Bonding1.1.8Intermolecular Forces1.1.9Intermolecular Forces 21.1.10End of Topic Test - Bonding1.1.11Relative Masses1.1.12The Mole1.1.13Molar Calculations1.1.14Molar Calculations 21.1.15Empirical & Molecular Formulae1.1.16Balanced Equations1.1.17Percentage Yield1.1.18End of Topic Test - Amount of Substance
1.2Properties of Substances
1.2.1The Periodic Table1.2.2Ionisation Energy1.2.3Factors Affecting Ionisation Energies1.2.4Trends of Ionisation1.2.5Trends in the Periodic Table1.2.6Polarity1.2.7Metals & Non-Metals1.2.8Alkali Metals1.2.9Alkaline Earth Metals1.2.10Reactivity of Alkaline Earth Metals1.2.11Redox1.2.12Transition Metals1.2.13Redox Reactions of Transition Metals
1.3Cell Structure & Function
1.4Cell Specialisation
1.5Tissue Structure & Function
1.5.1Human Gas Exchange1.5.2Blood Vessels1.5.3Atherosclerosis1.5.4Skeletal Muscle1.5.5Slow & Fast Twitch Fibres1.5.6Neurones1.5.7Speed of Transmission1.5.8Action Potentials1.5.9End of Topic Test - Neurones & Action Potentials1.5.10Synapses1.5.11Types of Synapse1.5.12Medical Application1.5.13End of Topic Test - Synapses1.5.14Chemical Brain Imbalances1.5.15Effect of Drugs on the Brain
1.6Working with Waves
1.7Waves in Communication
2Practical Scientific Procedures and Techniques
3Science Investigation Skills
3.1Scientific Processes
3.2Data Handling & Analysis
3.3Enzymes in Action
3.4Diffusion
3.5Plants & Their Environment
3.6Energy Content in Fuels
4Principles of Science II
4.1Extracting Elements
4.2Relating Properties to use of Substances
4.3Organic Chemistry
4.4Energy Changes in Industry
4.5The Circulatory System
4.5.1The Circulatory System4.5.2Blood Vessels4.5.3Blood Transfusion & the ABO Rhesus System4.5.4The Heart4.5.5The Cardiac Cycle4.5.6Cardiac Output4.5.7Coordination of Heart Action4.5.8Heart Dissection4.5.9Controlling Heart Rate4.5.10Electrocardiograms4.5.11Cardiovascular Disease4.5.12Investigating Heart Rates
4.6Ventilation & Gas Exchange
4.7Urinary System
4.9Thermal Physics
4.9.1Power & Efficiency4.9.2Work & Energy4.9.3Conservation of Energy4.9.4Pressure4.9.5First Law of Thermodynamics4.9.6Second Law of Thermodynamics4.9.7Heat Engines, Heat Pumps & Refrigerators4.9.8Non-Flow Processes4.9.9p-V Diagrams4.9.10Ideal Gases4.9.11Ideal Gases 24.9.12Thermal Energy Transfer4.9.13Thermal Energy Transfer Experiments
4.10Materials
5Contemporary Issues in Science
5.1Contemporary Issues in Science
5.2Analysing Scientific Information
Jump to other topics
1Principles of Science I
1.1Structure & Bonding
1.1.1Atomic Model1.1.2Electron Shells, Sub-Shells & Orbitals1.1.3Ionic Bonding1.1.4Representing Ionic Bonds1.1.5Covalent Bonding1.1.6Representing Covalent Bonds1.1.7Metallic Bonding1.1.8Intermolecular Forces1.1.9Intermolecular Forces 21.1.10End of Topic Test - Bonding1.1.11Relative Masses1.1.12The Mole1.1.13Molar Calculations1.1.14Molar Calculations 21.1.15Empirical & Molecular Formulae1.1.16Balanced Equations1.1.17Percentage Yield1.1.18End of Topic Test - Amount of Substance
1.2Properties of Substances
1.2.1The Periodic Table1.2.2Ionisation Energy1.2.3Factors Affecting Ionisation Energies1.2.4Trends of Ionisation1.2.5Trends in the Periodic Table1.2.6Polarity1.2.7Metals & Non-Metals1.2.8Alkali Metals1.2.9Alkaline Earth Metals1.2.10Reactivity of Alkaline Earth Metals1.2.11Redox1.2.12Transition Metals1.2.13Redox Reactions of Transition Metals
1.3Cell Structure & Function
1.4Cell Specialisation
1.5Tissue Structure & Function
1.5.1Human Gas Exchange1.5.2Blood Vessels1.5.3Atherosclerosis1.5.4Skeletal Muscle1.5.5Slow & Fast Twitch Fibres1.5.6Neurones1.5.7Speed of Transmission1.5.8Action Potentials1.5.9End of Topic Test - Neurones & Action Potentials1.5.10Synapses1.5.11Types of Synapse1.5.12Medical Application1.5.13End of Topic Test - Synapses1.5.14Chemical Brain Imbalances1.5.15Effect of Drugs on the Brain
1.6Working with Waves
1.7Waves in Communication
2Practical Scientific Procedures and Techniques
3Science Investigation Skills
3.1Scientific Processes
3.2Data Handling & Analysis
3.3Enzymes in Action
3.4Diffusion
3.5Plants & Their Environment
3.6Energy Content in Fuels
4Principles of Science II
4.1Extracting Elements
4.2Relating Properties to use of Substances
4.3Organic Chemistry
4.4Energy Changes in Industry
4.5The Circulatory System
4.5.1The Circulatory System4.5.2Blood Vessels4.5.3Blood Transfusion & the ABO Rhesus System4.5.4The Heart4.5.5The Cardiac Cycle4.5.6Cardiac Output4.5.7Coordination of Heart Action4.5.8Heart Dissection4.5.9Controlling Heart Rate4.5.10Electrocardiograms4.5.11Cardiovascular Disease4.5.12Investigating Heart Rates
4.6Ventilation & Gas Exchange
4.7Urinary System
4.9Thermal Physics
4.9.1Power & Efficiency4.9.2Work & Energy4.9.3Conservation of Energy4.9.4Pressure4.9.5First Law of Thermodynamics4.9.6Second Law of Thermodynamics4.9.7Heat Engines, Heat Pumps & Refrigerators4.9.8Non-Flow Processes4.9.9p-V Diagrams4.9.10Ideal Gases4.9.11Ideal Gases 24.9.12Thermal Energy Transfer4.9.13Thermal Energy Transfer Experiments
4.10Materials
5Contemporary Issues in Science
5.1Contemporary Issues in Science
5.2Analysing Scientific Information
Practice questions on Measuring Gas Exchange
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