6 main things that need to be controlled in the body:
1) the body temperature cant get too hot or cold. This is monitored by the thermoregulatory centre in the brain. This centre has receptors sensitive to the temperature of the blood flowing through the brain. Receptors in the skin also send messages to the centre about temperature. Sweating and vasodilation help to cool the body and shivering and vasoconstriction help to warm it up. More water is lost when it is hot and more water had to be taken in to balance this loss.
2) water content mustn't get too high or low. Water is taken in as food and drink and lost in urine, sweat and respiration.
3) ion content must be kept constant. Ion is taken in through food (sodium) and is then absorbed into the blood. If ion…