Explore the role Of respiratory system in regulation of blood gases.

• Creating models is one way to understand and communicate scientific information
• Examine human respiration
• Time required: one to two 50 minutes class periods

Using bromothymol blue (BTB) as an indicator, students conduct a qualitative investigation. The amount of carbon dioxide in their exhaled breath is then quantitatively measured using the indicator to perform a simple titration. The combination of these steps demonstrates the function of the lungs in providing surface area for oxygen to enter and carbon dioxide wastes to leave the blood.