Respiratory Function Lab

What's the Point?

By the end of this lesson, you will be able to measure and analyze how breathing rate changes with activity and explain how the respiratory system works with the cardiovascular system to maintain homeostasis.

Background

Your respiratory system allows oxygen to enter the body and carbon dioxide to leave. When you breathe in, oxygen moves from your lungs into your blood. When you breathe out, carbon dioxide (a waste product of energy use) is released.

During exercise, your muscles use oxygen faster. To keep up, your breathing rate increases to supply more oxygen and remove extra carbon dioxide. This process keeps your internal balance stable, or in homeostasis.

Key terms to remember:

- Respiration: The process of exchanging gases between the body and the environment.
- Breathing Rate: The number of breaths per minute.
- Spirometry: A method used to measure the amount and speed of air a person can inhale and exhale.
- Homeostasis: The body’s ability to maintain stable internal conditions despite changes around it.

In this lab, you will measure how your breathing changes before and after light exercise, just as you did with your heart rate.

Materials Needed

Stopwatch or phone timer
Notebook or lab sheet
Quiet place to sit
Optional: a straw and cotton ball (for a bonus airflow activity)

Procedure

Woman sitting and measuring breathing rate

Measure your resting breathing rate.

Sit quietly.
Count the number of times you breathe (inhale and exhale once) in one minute.
Record this number as your resting breathing rate.

Exercise for one minute.

Jog in place, do jumping jacks, or dance.
Immediately after exercise, count your breaths for one minute again. Record this as your active breathing rate.

Recovery period.

Sit and rest for one minute, then count again.
Repeat a third time after three minutes.

Optional Airflow Activity:

Place a cotton ball on a table.
Use a straw to blow air at it from different distances (5 cm, 10 cm, 15 cm).
Observe how the force of air changes as your “exhalation distance” changes.
This models how your lungs can adjust airflow to meet different needs.

Data Table
Condition	Breaths per Minute	Notes / Observations
Resting
Immediately after Exercise
1 Minute After
3 Minutes After

Analysis and Reflection

How did your breathing rate change after exercise?
How quickly did it return to normal?
Why does your breathing rate increase when you are active?
How do the respiratory and cardiovascular systems work together during exercise?
What do your results tell you about your body’s ability to maintain homeostasis?

Extension (Optional)

Graph your breathing rate data from this lab and compare it to your heart rate data from the previous lesson. What patterns do you notice? How do both systems respond to physical activity in similar ways?

Lab Notebook Entry #6
Review the instructions for each of the sections below.

Purpose – State what this investigation was designed to model about respiratory function and breathing rate changes.
Observations – Write one or two sentences describing what you noticed about your breathing during rest, activity, and recovery.
Analysis – Answer the Analysis and Reflection questions above in complete sentences using scientific reasoning.
Conclusion – Summarize what this experiment taught you about respiratory regulation, exercise response, and homeostasis.

Your respiratory system automatically adjusts to the body’s needs. When you move, your lungs work harder to bring in oxygen and release carbon dioxide. This experiment shows how breathing and heart rate are connected—both systems constantly communicating to keep your body balanced and healthy.

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