Question

why might a cell in your body not change, even in the presence of a hormone signal ?

Answer 1

Hormones are part of long distance signalling i.e., they are being secreted and taken to different regions through bloodstream. They are chemical messengers secreted by some endocrine glands.

As an important part of cell communication, different hormones are secreted by the endocrine glands into the bloodstream which  binds to cells only which has receptors. the recognition domain in the receptors recognises the signal molecule-hormone and binds to it.  Cells which doesnot have the respective functional receptors for the hormone is not directly influenced by the hormones or is not affected at all.

the receptors may be present on cell surface or may be intracellular receptors. catecholes and peptides bind on the cell surface receptors whereas thyrod hormonae and steroid hormone diffuse inside the cytoplasm.

since hormones are secreted in lesser concentration, it should be tighlty and correctly bound to the functional receptors to trigger cellular response

Hormones---> binds to the functional receptors found in the target cell---> which responds by cascade of events-----> give required cellular response