ChE power! A hands-on introduction to energy balances on the human body

Our lungs are membrane system that allows the exchange of O ₂, CO ₂, and H ₂O between the body and the air. When air is inhaled, oxygen is transported to the blood by diffusion through the alveolar membrane. Carbon dioxide is simultaneously removed from the blood to the air in the lungs, and is then exhaled. Oxygen in the blood is transported to cells where it oxidizes fats and carbohydrates to release energy, and carbon dioxide is a waste product of this reaction that must be removed. Breathing also plays a role in heat transfer and thermal regulation, since heat transferred to the air in the lungs is removed as sensible and latent heat during exhalation. We have developed a module based on a hands-on experiment that introduces chemical engineering principles through the exploration of the breathing and metabolic processes. Students use this information to (1) perform simple mass and energy balances on the lungs, (2) determine the total rate of energy expenditure (3) determine the composition of food oxidized for energy using reaction stoichiometry (4) use a process simulator to perform mass and energy balances on the breathing process and (5) to analyze the role of breathing in thermal regulation.