The interdependence of body systems is essential because
a. very few processes are controlled by hormones.
b. all systems work together to maintain homeostasis.
c. each system doesn't rely on the others to work.
d. each system can work independently on its own.

The interdependence of body systems is essential because they work together to maintain homeostasis - b. Homeostasis is the default, optimal range of functioning for biological organisms. It wouldn't be achieved without the simultaneous working of many different organ systems. 

The pituitary gland is a structure in our brain that produces different types of specialised hormones, including growth hormone (also referred to as human growth hormone or HGH). The roles of growth hormone include influencing our height, and helping build our bones and muscles.