Praxis II: Biology Content Knowledge Exam Prep

Answer: E, In the blood, humans use homeostatic mechanisms to regulate the content of all of the above. In addition, homeostasis is used to regulate the acid-base content and water levels in blood.

Key Takeaway: Homeostasis is the process by which a system, either open or closed, regulates its internal environment to maintain stability. While some animals are conformers that allow the external environment to influence its internal parameters, regulators such as humans have a complex network of activities that maintain constant internal stability. One example is the regulation of blood sugar content by insulin and glucagon. Insulin is released by the pancreas when blood sugar is too high, and glucagon is released when blood sugar is too low. These two hormones work in concert to maintain sugar content within a normal range.