The maintenance of a constant internal environment is known as what?

• A. Homeostasis
• B. Metabolism
• C. Respiration
• D. Digestion

Answer: (A)

Maintaining a constant internal environment is homeostasis. This means keeping things like body temperature, pH, and the balance of water and salts in the body within narrow limits, even when the outside conditions change. The body uses feedback mechanisms to do this, sensing a change, comparing it to a normal set point, and triggering responses to restore balance. For example, when you’re hot, sweating and widening blood vessels help cool you down; when you’re cold, shivering and conserving heat help raise your body temperature. Blood glucose is kept steady by hormones such as insulin and glucagon, and the kidneys help regulate water balance. The other terms describe different processes: metabolism covers all the chemical reactions that provide energy and build molecules; respiration is the cellular release of energy using oxygen; digestion is the breakdown of food in the digestive system.