Homeostasis Experiments for High School Biology

Homeostasis experiments are an important unit in high school biology classes that help students better understand vital involuntary body systems that are not easily observed. Through a variety of experiments, students can observe the effects of the cardiovascular system and endocrine system on human quality of life. Teachers should always review the scientific method and safety procedures before beginning any classroom experiment.

Students will determine the effects of various fluids on the endocrine system by sampling different beverages and recording data collected from urine samples. Complete the experiment over four days. Students should drink tap water on the first day, carbonated dark soda on the second day, saltwater on the third day and coffee on the final day. Provide litmus paper so a student can test the pH level of urine during each trip to the restroom on these days. Students should also record whether their urine is dark or light. Discuss the results and draw conclusions about the effect each beverage has on the human body and the importance of kidneys in maintaining homeostasis through proper filtration.

Teachers will assign students in groups of four and provide each group with a stopwatch, stethoscope and graphing paper. Instruct students to form a hypothesis about how external influences will affect a person's cardiovascular system. Show students how to measure each group member's resting heart rate with the stethoscope while the subject is seated and tell them to record the data on the graphing paper. Have students perform a relaxation technique, such as deep breathing exercises or meditation, and instruct students to record heart rates again. Perform an activity that will startle students, such as popping a paper bag suddenly behind them. Immediately check the student's heart rate. In the final phase of the experiment, introduce a noise that is considered irritating by most people, such as the whine of a siren. Test heart rate every three minutes, increasing the volume of the noise during each interval. Discuss results and determine whether each student's hypothesis was confirmed or disputed by the data collected.

In a first-period biology class, the teacher should place students with partners and show one member of each group how to measure each blood pressure using the sphygmomanometer while his partner is seated. Students will need to record the data of each blood pressure check during the experiment. Instruct seated students to rise slowly and test blood pressure levels when the student stands. Students should return to their seats and after five minutes stand up quickly. Their partners should immediately check their blood pressure. The teacher should instruct students to return to class the following day without eating breakfast and repeat the experiment. Teachers should be sure to provide breakfast items after blood pressure levels are tested again while the class discusses the different results achieved during each experiment and the impact of proper nutrition on homeostasis.

Discuss common physical examples of the human body's attempts to achieve homeostasis in relation to external temperature, including sweating and shivering. Assign students to groups of four and instruct group members to record each other's body temperature with a thermometer and their heart rates with a stethoscope and stop watch. Instruct students to submerge their faces in a basin of ice water for 30 seconds and measure body temperature and heart rate after they step away. Repeat the experiment with a basin of very warm water. Discuss the results and explain that when subjected to colder temperatures, the human heart will slow in order to preserve oxygen levels within the body to achieve homeostasis.