What factor determines if circulating hormones will elicit a response in target organs?

A. The ability of the hormone to work without entering the blood.

B. The ability of the hormone to attach to an intracellular receptor.

C. The hormone must be secreted from a specific endocrine gland in a sustained manner.

D. The location of a specific receptor that will bind to a particular hormone.

D

This was the 5^th most difficult question in the paper for candidates with most incorrectly selecting option B. What made this selection incorrect is the term 'intracellular' which implies that the receptor is inside the cell. A circulating hormone is outside the cell and so must have a receptor on the cell membrane surface.