Recognize that several mechanisms are involved in maintaining homeostasis.

• Describe how the circulatory system and respiratory system interact to maintain pH and oxygen levels.
• Explain how the circulatory system and sweat glands interact to maintain a constant body temperature.
• Describe how the processes of breathing, circulation, and exercise are interrelated.
• Explain the function of breathing to oxygen and carbon dioxide exchange.
• Describe the role of the kidneys in regulating blood pH.
• Describe how the kidneys regulate the salt and water content of the body.

Understand how the circulatory, respiratory, digestive, and excretory systems function.

• Explain how the kidneys are able to rid the body of waste products.
• Describe the functions of the liver that are related to digestion.
• Explain why a strongly pumping heart and open arteries and veins are essential to good health.
• Explain the role of various organs of the digestive system in the enzymatic, mechanical, and chemical digestion of foods.