Answer: By Hormonal action and Nervous coordination
Explanation:
Hormones are substances produced by one tissue and conveyed by the bloodstream to another to effect physiological activity. Homeostasis is the maintenance of a stable internal environment in the body.
Body systems such as digestive, circulatory, excretory systems etc, all are coordinated to achieve a STABLE INTERNAL ENVIRONMENT by the aid of HORMONES AND/OR NERVOUS COORDINATION.
For Example: the vasodilation of blood vessels during hot weather, and the opposite action of vasoconstriction during cold weather are both controlled by Hormonal action and nervous coordination which leads to a stable body temperature preventing excess heat accumulation.
Also, Nervous system controls the body systems, such that the muscle contractions are joined to actions like sweating, breathing, respiration etc
So, to maintain homeostasis hormonal action and Nervous coordination is necessary.
Well for the very last sentence it would be if any of the organs shut down it could seriously hurt someone or possibly even kill them if their brain,heart or some other important organ shuts down it could kill them.
There are other minor organs where if it shuts down it wouldn't really hurt the person too much. Sorry I couldn't help you with the other ones though.
