7.3 - Measuring the process of ventilation Flashcards
What factors affect the amount of gaseous exchange needed in the lungs?
The amount of gaseous exchange depends on your size and level of activity.
Why must the gaseous exchange system be adaptable?
The gaseous exchange system must respond to the varying demands of the body to meet oxygen requirements and remove carbon dioxide efficiently.
What are the four main ways that breathing can be scientifically measured?
- vital capacity
- tidal volume
- breathing rate
- oxygen uptake
What is vital capacity?
Vital capacity is the maximum volume of air that can be breathed in after the strongest possible exhalation followed by the deepest possible inhalation.
What is tidal volume?
Tidal volume is the volume of air that is breathed in or out during normal breathing at rest, with each resting breathe.
What is the tidal volume in most adults at rest?
It is around 500 cm³ in most adults at rest, using about 15% of the vital capacity.
What is breathing rate?
Breathing rate is the number of breaths taken in one minute. One breath includes inhaling and exhaling.
What is oxygen uptake?
Oxygen uptake is the volume of oxygen used by someone in a given time.
What are the 3 ways of measuring the capacity of the lungs?
- A peak flow meter
- Vitalographs
- Spirometer
What does a peak flow meter measure? Who is it used by, and what does it monitor?
A peak flow meter measures the rate at which air can be expelled from the lungs. It is often used by people with asthma to monitor lung function.
What is a vitalograph, and how does it differ from a peak flow meter? What does it produce?
A vitalograph is a more sophisticated version of a peak flow meter. It produces a graph of the amount of air a patient can breathe out and the speed of exhalation.
What is the forced expiratory volume in 1 second (FEV1)?
The forced expiratory volume in 1 second (FEV1) is the volume of air a person can breathe out in one second, measured using a vitalograph.
What does a spirometer measure?
A spirometer measures different aspects of lung volume and investigates breathing patterns. breathing measurements such as vital capacity, tidal volume, breathing rate, and oxygen uptake.
Are there different types of spirometers?
Yes, there are many forms of spirometers, but they all function on the same basic principle.
How is carbon dioxide managed in a spirometer?
Soda lime absorbs carbon dioxide from the exhaled air to prevent its concentration from becoming too high, which could cause respiratory distress.
How does a spirometer record breathing patterns?
As the subject breathes through the spirometer, a trace is either drawn on a rotating drum of paper or produced digitally for analysis.
How does a spirometer measure oxygen uptake?
As the subject breathes, oxygen is extracted from the air in the spirometer. The total volume of air in the spirometer decreases, and this change in volume is used to calculate oxygen uptake.
What measurements can be obtained using a spirometer?
A spirometer can measure:
1. Vital capacity
2. Tidal volume
3. Breathing rate
4. Oxygen uptake
What does a spirometer trace represent?
A spirometer trace represents breathing patterns and measurements in the form of a graph drawn on paper or digitally created by a computer.
What is residual volume?
Residual volume is the small amount of air that is always retained in the lungs, even after forceful exhalation. This cannot be measured directly.
Why is residual volume important?
Residual volume prevents the lungs from collapsing and ensures that gas exchange continues between breaths.
What aspects of lung volume can be measured?
- Tidal volume
- Vital capacity
- Inspiratory reserve volume
- Expiratory reserve volume
- Residual volume
- Total lungs capacity
What is inspiratory reserve volume?
The maximum volume of air you can breathe in over and above a normal inhalation.
What is expiratory reserve volume?
The extra amount of air you can force out of your lungs over and above the normal tidal volume.
How is the total lung capacity calculated?
The sum of the vital capacity and the residual volume.
What is the breathing rate?
The number of breaths taken per minute.
What is the ventilation rate?
The total volume of air inhaled in one minute.
How is ventilation rate calaculated?
Ventilation rate = tidal volume × breathing rate (per minute)
How does the tidal volume change during exercise?
The tidal volume can increase from 15% to as much as 50% of the vital capacity to meet the body’s oxygen demands.
What happens to the breathing rate during increased oxygen demands (e.g., exercise)? Why?
The breathing rate increases to facilitate higher ventilation and oxygen uptake.
How does the body meet increased oxygen demands?
By increasing tidal volume and breathing rate, which enhances ventilation and oxygen uptake during gaseous exchange.
How do you convert tidal volume from cm³ to dm³?
Divide the tidal volume in cm³ by 1,000.
e.g., 500cm³ –> 0.5dm³
EXAMPLE QUESTION:
A person took 15 breaths in a minute, and their tidal volume was 500 cm³. What is their ventilation rate in dm³ min⁻¹?
- Convert tidal volume to dm³:
500cm³ = 0.5dm³ - Substitute values into the formula:
Ventilationrate = 0.5dm³ × 15min⁻¹ - Calculate ventilationrate:
Ventilation rate= 7.5 dm³min⁻¹
Why is it important to convert tidal volume from cm³ to dm³ when calculating ventilation rate?
To ensure the units match for consistent calculations, as ventilation rate is expressed in dm³ min⁻¹.
Describe how you would investigate breathing rates in a school library. (3 marks)
- Measure breathing rate by counting the number of breaths taken by individuals in one minute.
- Ensure participants are at rest and comfortable in a quiet environment.
- Record results and repeat the measurements for multiple individuals to ensure reliability.
Describe the relationships between tidal volume, breathing rate, and oxygen uptake. (4 marks)
- Tidal volume is the volume of air inhaled or exhaled in a single breath.
- Breathing rate is the number of breaths taken per minute.
- Oxygen uptake depends on the total ventilation rate, which is calculated as Tidalvolume × Breathingrate
- During exercise or increased oxygen demand, both tidal volume and breathing rate increase to meet the body’s needs.
A dog is under stress during a visit to the vet and pants, but the ventilation rate remains steady. Suggest a possible explanation for these observations. (2 marks)
- Panting involves rapid, shallow breaths that do not significantly increase tidal volume.
- As a result, although the breathing rate increases, the ventilation rate remains steady because the overall volume of air moved per minute does not change.
