Consider the following hormones and their role in the workings of the endocrine system: Where the hormone is produced. Hormone(s) secreted. Hormone function. Adrenal glands. Aldosterone. Regulates salt, water balance, and blood pressure.
Sometimes there are tissue-specific mutations that control formation of certain tissues and/or organs. For instance, if mutation affects skin then the skin would be wrinkly/ugly but organism would still develop.
Organisms grow because cells are dividing to produce more and more cells. In human bodies, nearly two trillion cells divide every day. Watch cells divide in this time lapse video of an animal cell (top) and an E. coli bacteria cell (bottom).