The function of the thyroid gland is regulated by a hormonal control circuit. The distribution of hormones in the brain (hypothalamus, pituitary gland) regulates the hormone concentration in the thyroid and vice versa. If this control circuit is out of balance, an hyper- (hyperthyroidism) or hypofunction (hypothyroidism) is the consequence. 

This illustration visualizes the complex process in a comprehensible manner, through the comparison of the sides, thus facilitating the understanding and the memory. 

The illustration was part of my Bachelor thesis at ZHdK and a collaboration with the medical online-learning platform AMBOSS (Miamed).