The water content of the body: You take water into the body when you eat and drink. Too much or too little water in the cells can damage or destroy them. Water leaves the body via the lungs when we breathe out. Water leaves the body via the skin when we sweat to cool us down. Your kidneys can change the amount of water lost in urine.
The ion content of the body: Ions are lost via the skin when we sweat. Excess ions are lost via the kidneys in urine.
Temperature: It is vital to maintain the temperature at which enzymes work best. Enzymes are protein molecules that control reactions inside and outside of cells. They are sensitive to changes in the temperature and work best at body temperature: 37 degrees Celsius Sweating and shivering are responses controlled by the nervous system which help to control body temperature.
Blood sugar levels: We take in sugars as carbohydrates in a meal. Glucose levels in the blood are kept constant by hormones made in the pancreas.