Activity 7.1.4 - Homeostasis lab

Introduction

Homeostasis is the process of maintaining balanced internal conditions, even if external conditions change. Imagine you step outside in the middle of winter. Does your internal body temperature immediately drop to the temperature of the frigid Minnesota tundra? Nope. Thankfully we have built in mechanisms that help maintain a constant temperature (sweating and shivering are a few). Our body also maintains a stable internal balance of pH, oxygen and sugar levels among many others.

You will be investigating heart rate today. When our heart rate is increased, our body activates a series of steps to help bring it back to normal. The purpose of this lab is to first go through the scientific process to determine the effect of exercise on heart rate and second, to determine what pathways are involved in this process to maintain homeostasis.

Purpose

The purpose of this experiment is to determine how long it takes after exercise for your heart rate to return to its resting rate.

Procedure

Safety considerations: Make sure activities are safe for individual students (for example- no jumping on tables). For students with physical disabilities: students can choose another factor to explore its effect on heart rate (listening to heavy metal vs. classical music, sitting in a dark room, etc…)

1. Determine your resting heart rate. To do this, you will need a stopwatch and the instructions found here.

2. Record your resting heart rate: ______ beats per minute

3. Choose an exercise and an amount of time: I will exercise by doing ____________________ for ___ minutes.

Example: I will exercise by doing push-ups for one minute.

4. Make a hypothesis: If I ____(see above statement)__________________, then ______________.

 Example: If I do push-ups for one minute, then it will take 3 minutes for my heart rate to returning to its resting heart rate.

5. Carry out your experiment as you described. Test your heart rate every minute and record your data on a chart (you will need to make this!)

Results/Summary

        Write a two-three paragraph summary of your results that includes the following information:

• Recap the experiment (Explain step-by-step so I could read your description and be able to carry out the experiment in the exact way you did)
• Identify the independent and dependent variable
• Include your data chart
• Did your evidence support or refute your hypothesis? Explain.
• Give two options for how you could change the experiment in the future.
• Use internet resources to determine what mechanisms our bodies use to control heart rate. Explain what parts of the brain are used and what hormones are involved. Cite sources at the end.