List and discuss the 3 major chemical classes of hormones, amines, proteins, and steroids. Discuss why protein hormones cannot be taken by mouth.
Indicate that hormones are only released when there is a need. The stimuli for release being the change in blood levels of hormones as received by chemoreceptors.
Using insulin as an example, examine the steps in the negative feedback system which will bring about an increase or decrease in the blood hormone level.