Question

what organ is this, and what organ system does it belong to?

Explanation:

The organ shown (the highlighted structure in the brain) is the pituitary gland. The pituitary gland is part of the endocrine system, which is responsible for producing and secreting hormones that regulate various bodily functions. It can also be considered part of the nervous system due to its close connection with the brain (hypothalamus), but its primary role in hormone production makes the endocrine system the main system it belongs to.

Answer:

The organ is the pituitary gland, and it belongs to the endocrine system (it also has close ties to the nervous system, but primarily the endocrine system).