NSES Content Standard C Life Science: Regulation and behavior Grades 5-8, page 157 Regulation of an organism's internal environment involves sensing the internal environment and changing physiological activities to keep conditions within the range required to survive.

 
Benchmark 5C The Living Environment: Cells
Grades 9-12, page 114
Most cells function best within a narrow range of temperature and acidity. At very low temperatures, reaction rates are too slow. High temperatures and/or extremes of acidity can irreversibly change the structure of most protein molecules. Even small changes in acidity can alter the molecules and how they interact. Both single cells and multicellular organisms have molecules that help to keep the cell's acidity within a narrow range.

Benchmark 6C The Human Organism: Basic Functions
Grades 3-5, page 136
The brain gets signals from all parts of the body telling what is going on there. The brain also sends signals to parts of the body to influence what they do.

Benchmark 6C The Human Organism: Basic Functions
Grades 6-8, page 137
Hormones are chemicals from glands that affect other body parts. They are involved in helping the body respond to danger and in regulating human growth, development, and reproduction.

Benchmark 6C The Human Organism: Basic Functions
Grades 6-8, page 137
Interactions among the senses, nerves, and brain make possible the learning that enables human beings to cope with changes in their environment.

Benchmark 11C Common Themes: Constancy and Change
Grades 6-8, page 274
Many systems contain feedback mechanisms that serve to keep changes within specified limits.